Xen devel - Oct 2013 - [PATCHv7 00/16] Linux: FIFO-based event channel ABI

This is the complete Linux guest-side implementation of the FIFO-based
event channel ABI described in this design document:

  http://xenbits.xen.org/people/dvrabel/event-channels-F.pdf

The Xen implementation is now available in xen-unstable.

Note that __startup_pirq() was never ideal as failure when binding a
PIRQ to an event channel cannot be propagated to the calling driver
since the irq_startup callback cannot return an error.  This series
adds another (very unlikely) failure point to __startup_pirq().

I have a half-bakedpatch series to refactor when PIRQs are setup and
torn down but this won''t be ready for a while and I do not think this
is a prerequisite for applying the FIFO-based ABI series.

Patch 1 is a obvious refactoring of common code.

Patch 2-6 prepare for supporting multiple ABIs.

Patch 7 adds the low-level evtchn_ops hooks.

Patch 8-9 add an additional hook for ABI-specific per-port setup
(used for expanding the event array as more event are bound).

Patch 10 allows many more event channels to be supported by altering
how the event channel to irq map is allocated.  Note that other
factors limit the number of supported IRQs (IRQs is 8192 + 64 *
NR_CPUS).

Patch 11 is some trival refactoring.

Patch 12 removes a limit on the number of event channels supported by
the xen-evtchn driver.

Patch 13 adds the hypervisor ABI.

Patches 14-15 Set the priority of VIRQ_TIMER events to the highest.

Patch 16 adds the FIFO-based ABI implementation.

Changes in v7:

- Add xen.fifo_events command line option (defaults to true).
- Use xen_evtchn_nr_channels() in xen_evtchn driver.
- Drop unnecessary test in evtchn_fifo_unmask()
- Refactor irq_info setup/cleanup a bit.

Changes in v6:

- nlevel -> 2l to match naming in Xen.

Changes in v5 (v4 not posted):

- Set priority of VIRQ_TIMER.
- Remove NR_EVENT_CHANNELS limit from xen-evtchn driver.
- Licence drivers/xen/events/fifo.c under a dual MIT/GPLv2.

Changes in v3:

- Support suspend/resume by reinitializing the control blocks on resume.
- Only init control block if one does not exist (should fix CPU
  hotplug).

From: David Vrabel <david.vrabel@citrix.com>

These two function did the same thing with different parameters, put
the common bits in retrigger_evtchn().

This changes the return value of resend_irq_on_evtchn() but the only
caller (in arch/ia64/xen/irq_xen.c) ignored the return value so this
is fine.

Signed-off-by: David Vrabel <david.vrabel@citrix.com>
Acked-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
---
 drivers/xen/events.c |   27 +++++++++------------------
 1 files changed, 9 insertions(+), 18 deletions(-)

diff --git a/drivers/xen/events.c b/drivers/xen/events.c
index 4035e83..ddcdbb5 100644
--- a/drivers/xen/events.c
+++ b/drivers/xen/events.c
@@ -1558,13 +1558,13 @@ static int set_affinity_irq(struct irq_data *data, const
struct cpumask *dest,
 	return rebind_irq_to_cpu(data->irq, tcpu);
 }
 
-int resend_irq_on_evtchn(unsigned int irq)
+static int retrigger_evtchn(int evtchn)
 {
-	int masked, evtchn = evtchn_from_irq(irq);
+	int masked;
 	struct shared_info *s = HYPERVISOR_shared_info;
 
 	if (!VALID_EVTCHN(evtchn))
-		return 1;
+		return 0;
 
 	masked = sync_test_and_set_bit(evtchn, BM(s->evtchn_mask));
 	sync_set_bit(evtchn, BM(s->evtchn_pending));
@@ -1574,6 +1574,11 @@ int resend_irq_on_evtchn(unsigned int irq)
 	return 1;
 }
 
+int resend_irq_on_evtchn(unsigned int irq)
+{
+	return retrigger_evtchn(evtchn_from_irq(irq));
+}
+
 static void enable_dynirq(struct irq_data *data)
 {
 	int evtchn = evtchn_from_irq(data->irq);
@@ -1608,21 +1613,7 @@ static void mask_ack_dynirq(struct irq_data *data)
 
 static int retrigger_dynirq(struct irq_data *data)
 {
-	int evtchn = evtchn_from_irq(data->irq);
-	struct shared_info *sh = HYPERVISOR_shared_info;
-	int ret = 0;
-
-	if (VALID_EVTCHN(evtchn)) {
-		int masked;
-
-		masked = sync_test_and_set_bit(evtchn, BM(sh->evtchn_mask));
-		sync_set_bit(evtchn, BM(sh->evtchn_pending));
-		if (!masked)
-			unmask_evtchn(evtchn);
-		ret = 1;
-	}
-
-	return ret;
+	return retrigger_evtchn(evtchn_from_irq(data->irq));
 }
 
 static void restore_pirqs(void)
-- 
1.7.2.5

From: David Vrabel <david.vrabel@citrix.com>

Because the guest-side binding of an event to a VCPU (i.e., setting
the local per-cpu masks) is always explicitly done after an event
channel is bound to a port, there is no need to initialize all
possible events as bound to VCPU 0 at start of day or after a resume.

Signed-off-by: David Vrabel <david.vrabel@citrix.com>
---
 drivers/xen/events.c |   22 ----------------------
 1 files changed, 0 insertions(+), 22 deletions(-)

diff --git a/drivers/xen/events.c b/drivers/xen/events.c
index ddcdbb5..1e2c74b 100644
--- a/drivers/xen/events.c
+++ b/drivers/xen/events.c
@@ -334,24 +334,6 @@ static void bind_evtchn_to_cpu(unsigned int chn, unsigned
int cpu)
 	info_for_irq(irq)->cpu = cpu;
 }
 
-static void init_evtchn_cpu_bindings(void)
-{
-	int i;
-#ifdef CONFIG_SMP
-	struct irq_info *info;
-
-	/* By default all event channels notify CPU#0. */
-	list_for_each_entry(info, &xen_irq_list_head, list) {
-		struct irq_desc *desc = irq_to_desc(info->irq);
-		cpumask_copy(desc->irq_data.affinity, cpumask_of(0));
-	}
-#endif
-
-	for_each_possible_cpu(i)
-		memset(per_cpu(cpu_evtchn_mask, i),
-		       (i == 0) ? ~0 : 0, NR_EVENT_CHANNELS/8);
-}
-
 static inline void clear_evtchn(int port)
 {
 	struct shared_info *s = HYPERVISOR_shared_info;
@@ -1778,8 +1760,6 @@ void xen_irq_resume(void)
 	unsigned int cpu, evtchn;
 	struct irq_info *info;
 
-	init_evtchn_cpu_bindings();
-
 	/* New event-channel space is not ''live'' yet. */
 	for (evtchn = 0; evtchn < NR_EVENT_CHANNELS; evtchn++)
 		mask_evtchn(evtchn);
@@ -1890,8 +1870,6 @@ void __init xen_init_IRQ(void)
 	for (i = 0; i < NR_EVENT_CHANNELS; i++)
 		evtchn_to_irq[i] = -1;
 
-	init_evtchn_cpu_bindings();
-
 	/* No event channels are ''live'' right now. */
 	for (i = 0; i < NR_EVENT_CHANNELS; i++)
 		mask_evtchn(i);
-- 
1.7.2.5

From: Wei Liu <wei.liu2@citrix.com>

In preparation for adding event channel port ops, add
test_and_set_mask().

Signed-off-by: Wei Liu <wei.liu2@citrix.com>
Signed-off-by: David Vrabel <david.vrabel@citrix.com>
Reviewed-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
---
 drivers/xen/events.c |   11 ++++++++---
 1 files changed, 8 insertions(+), 3 deletions(-)

diff --git a/drivers/xen/events.c b/drivers/xen/events.c
index 1e2c74b..359e983 100644
--- a/drivers/xen/events.c
+++ b/drivers/xen/events.c
@@ -352,6 +352,12 @@ static inline int test_evtchn(int port)
 	return sync_test_bit(port, BM(&s->evtchn_pending[0]));
 }
 
+static inline int test_and_set_mask(int port)
+{
+	struct shared_info *s = HYPERVISOR_shared_info;
+	return sync_test_and_set_bit(port, BM(&s->evtchn_mask[0]));
+}
+
 
 /**
  * notify_remote_via_irq - send event to remote end of event channel via irq
@@ -1493,7 +1499,6 @@ void rebind_evtchn_irq(int evtchn, int irq)
 /* Rebind an evtchn so that it gets delivered to a specific cpu */
 static int rebind_irq_to_cpu(unsigned irq, unsigned tcpu)
 {
-	struct shared_info *s = HYPERVISOR_shared_info;
 	struct evtchn_bind_vcpu bind_vcpu;
 	int evtchn = evtchn_from_irq(irq);
 	int masked;
@@ -1516,7 +1521,7 @@ static int rebind_irq_to_cpu(unsigned irq, unsigned tcpu)
 	 * Mask the event while changing the VCPU binding to prevent
 	 * it being delivered on an unexpected VCPU.
 	 */
-	masked = sync_test_and_set_bit(evtchn, BM(s->evtchn_mask));
+	masked = test_and_set_mask(evtchn);
 
 	/*
 	 * If this fails, it usually just indicates that we''re dealing with a
@@ -1548,7 +1553,7 @@ static int retrigger_evtchn(int evtchn)
 	if (!VALID_EVTCHN(evtchn))
 		return 0;
 
-	masked = sync_test_and_set_bit(evtchn, BM(s->evtchn_mask));
+	masked = test_and_set_mask(evtchn);
 	sync_set_bit(evtchn, BM(s->evtchn_pending));
 	if (!masked)
 		unmask_evtchn(evtchn);
-- 
1.7.2.5

From: Wei Liu <wei.liu2@citrix.com>

In preparation for adding event channel port ops, use set_evtchn()
instead of sync_set_bit().

Signed-off-by: Wei Liu <wei.liu2@citrix.com>
Signed-off-by: David Vrabel <david.vrabel@citrix.com>
Reviewed-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
---
 drivers/xen/events.c |    3 +--
 1 files changed, 1 insertions(+), 2 deletions(-)

diff --git a/drivers/xen/events.c b/drivers/xen/events.c
index 359e983..fec5da4 100644
--- a/drivers/xen/events.c
+++ b/drivers/xen/events.c
@@ -1548,13 +1548,12 @@ static int set_affinity_irq(struct irq_data *data, const
struct cpumask *dest,
 static int retrigger_evtchn(int evtchn)
 {
 	int masked;
-	struct shared_info *s = HYPERVISOR_shared_info;
 
 	if (!VALID_EVTCHN(evtchn))
 		return 0;
 
 	masked = test_and_set_mask(evtchn);
-	sync_set_bit(evtchn, BM(s->evtchn_pending));
+	set_evtchn(evtchn);
 	if (!masked)
 		unmask_evtchn(evtchn);
 
-- 
1.7.2.5

From: David Vrabel <david.vrabel@citrix.com>

events.c will be split into multiple files so move it into its own
directory.

Signed-off-by: David Vrabel <david.vrabel@citrix.com>
---
 drivers/xen/Makefile                           |    3 ++-
 drivers/xen/events/Makefile                    |    3 +++
 drivers/xen/{events.c => events/events_base.c} |    0
 3 files changed, 5 insertions(+), 1 deletions(-)
 create mode 100644 drivers/xen/events/Makefile
 rename drivers/xen/{events.c => events/events_base.c} (100%)

diff --git a/drivers/xen/Makefile b/drivers/xen/Makefile
index 14fe79d..d75c811 100644
--- a/drivers/xen/Makefile
+++ b/drivers/xen/Makefile
@@ -2,7 +2,8 @@ ifeq ($(filter y, $(CONFIG_ARM) $(CONFIG_ARM64)),)
 obj-$(CONFIG_HOTPLUG_CPU)		+= cpu_hotplug.o
 endif
 obj-$(CONFIG_X86)			+= fallback.o
-obj-y	+= grant-table.o features.o events.o balloon.o manage.o
+obj-y	+= grant-table.o features.o balloon.o manage.o
+obj-y	+= events/
 obj-y	+= xenbus/
 
 nostackp := $(call cc-option, -fno-stack-protector)
diff --git a/drivers/xen/events/Makefile b/drivers/xen/events/Makefile
new file mode 100644
index 0000000..f0bc607
--- /dev/null
+++ b/drivers/xen/events/Makefile
@@ -0,0 +1,3 @@
+obj-y += events.o
+
+events-y += events_base.o
diff --git a/drivers/xen/events.c b/drivers/xen/events/events_base.c
similarity index 100%
rename from drivers/xen/events.c
rename to drivers/xen/events/events_base.c
-- 
1.7.2.5

From: David Vrabel <david.vrabel@citrix.com>

In preparation for alternative event channel ABIs, move all the
functions accessing the shared data structures into their own file.

Signed-off-by: David Vrabel <david.vrabel@citrix.com>
---
 drivers/xen/events/Makefile          |    1 +
 drivers/xen/events/events_2l.c       |  348 +++++++++++++++++++++++++++++++
 drivers/xen/events/events_base.c     |  379 ++--------------------------------
 drivers/xen/events/events_internal.h |   74 +++++++
 include/xen/events.h                 |    2 +
 5 files changed, 442 insertions(+), 362 deletions(-)
 create mode 100644 drivers/xen/events/events_2l.c
 create mode 100644 drivers/xen/events/events_internal.h

diff --git a/drivers/xen/events/Makefile b/drivers/xen/events/Makefile
index f0bc607..08179fe 100644
--- a/drivers/xen/events/Makefile
+++ b/drivers/xen/events/Makefile
@@ -1,3 +1,4 @@
 obj-y += events.o
 
 events-y += events_base.o
+events-y += events_2l.o
diff --git a/drivers/xen/events/events_2l.c b/drivers/xen/events/events_2l.c
new file mode 100644
index 0000000..a77e98d
--- /dev/null
+++ b/drivers/xen/events/events_2l.c
@@ -0,0 +1,348 @@
+/*
+ * Xen event channels (2-level ABI)
+ *
+ * Jeremy Fitzhardinge <jeremy@xensource.com>, XenSource Inc, 2007
+ */
+
+#define pr_fmt(fmt) "xen:" KBUILD_MODNAME ": " fmt
+
+#include <linux/linkage.h>
+#include <linux/interrupt.h>
+#include <linux/irq.h>
+#include <linux/module.h>
+
+#include <asm/sync_bitops.h>
+#include <asm/xen/hypercall.h>
+#include <asm/xen/hypervisor.h>
+
+#include <xen/xen.h>
+#include <xen/xen-ops.h>
+#include <xen/events.h>
+#include <xen/interface/xen.h>
+#include <xen/interface/event_channel.h>
+
+#include "events_internal.h"
+
+/*
+ * Note sizeof(xen_ulong_t) can be more than sizeof(unsigned long). Be
+ * careful to only use bitops which allow for this (e.g
+ * test_bit/find_first_bit and friends but not __ffs) and to pass
+ * BITS_PER_EVTCHN_WORD as the bitmask length.
+ */
+#define BITS_PER_EVTCHN_WORD (sizeof(xen_ulong_t)*8)
+/*
+ * Make a bitmask (i.e. unsigned long *) of a xen_ulong_t
+ * array. Primarily to avoid long lines (hence the terse name).
+ */
+#define BM(x) (unsigned long *)(x)
+/* Find the first set bit in a evtchn mask */
+#define EVTCHN_FIRST_BIT(w) find_first_bit(BM(&(w)), BITS_PER_EVTCHN_WORD)
+
+static DEFINE_PER_CPU(xen_ulong_t [NR_EVENT_CHANNELS/BITS_PER_EVTCHN_WORD],
+		      cpu_evtchn_mask);
+
+void xen_evtchn_port_bind_to_cpu(struct irq_info *info, int cpu)
+{
+	clear_bit(info->evtchn, BM(per_cpu(cpu_evtchn_mask, info->cpu)));
+	set_bit(info->evtchn, BM(per_cpu(cpu_evtchn_mask, cpu)));
+}
+
+void clear_evtchn(int port)
+{
+	struct shared_info *s = HYPERVISOR_shared_info;
+	sync_clear_bit(port, BM(&s->evtchn_pending[0]));
+}
+
+void set_evtchn(int port)
+{
+	struct shared_info *s = HYPERVISOR_shared_info;
+	sync_set_bit(port, BM(&s->evtchn_pending[0]));
+}
+
+int test_evtchn(int port)
+{
+	struct shared_info *s = HYPERVISOR_shared_info;
+	return sync_test_bit(port, BM(&s->evtchn_pending[0]));
+}
+
+int test_and_set_mask(int port)
+{
+	struct shared_info *s = HYPERVISOR_shared_info;
+	return sync_test_and_set_bit(port, BM(&s->evtchn_mask[0]));
+}
+
+void mask_evtchn(int port)
+{
+	struct shared_info *s = HYPERVISOR_shared_info;
+	sync_set_bit(port, BM(&s->evtchn_mask[0]));
+}
+
+void unmask_evtchn(int port)
+{
+	struct shared_info *s = HYPERVISOR_shared_info;
+	unsigned int cpu = get_cpu();
+	int do_hypercall = 0, evtchn_pending = 0;
+
+	BUG_ON(!irqs_disabled());
+
+	if (unlikely((cpu != cpu_from_evtchn(port))))
+		do_hypercall = 1;
+	else {
+		/*
+		 * Need to clear the mask before checking pending to
+		 * avoid a race with an event becoming pending.
+		 *
+		 * EVTCHNOP_unmask will only trigger an upcall if the
+		 * mask bit was set, so if a hypercall is needed
+		 * remask the event.
+		 */
+		sync_clear_bit(port, BM(&s->evtchn_mask[0]));
+		evtchn_pending = sync_test_bit(port, BM(&s->evtchn_pending[0]));
+
+		if (unlikely(evtchn_pending && xen_hvm_domain())) {
+			sync_set_bit(port, BM(&s->evtchn_mask[0]));
+			do_hypercall = 1;
+		}
+	}
+
+	/* Slow path (hypercall) if this is a non-local port or if this is
+	 * an hvm domain and an event is pending (hvm domains don''t have
+	 * their own implementation of irq_enable). */
+	if (do_hypercall) {
+		struct evtchn_unmask unmask = { .port = port };
+		(void)HYPERVISOR_event_channel_op(EVTCHNOP_unmask, &unmask);
+	} else {
+		struct vcpu_info *vcpu_info = __this_cpu_read(xen_vcpu);
+
+		/*
+		 * The following is basically the equivalent of
+		 * ''hw_resend_irq''. Just like a real IO-APIC we
''lose
+		 * the interrupt edge'' if the channel is masked.
+		 */
+		if (evtchn_pending &&
+		    !sync_test_and_set_bit(port / BITS_PER_EVTCHN_WORD,
+					   BM(&vcpu_info->evtchn_pending_sel)))
+			vcpu_info->evtchn_upcall_pending = 1;
+	}
+
+	put_cpu();
+}
+
+static DEFINE_PER_CPU(unsigned int, current_word_idx);
+static DEFINE_PER_CPU(unsigned int, current_bit_idx);
+
+/*
+ * Mask out the i least significant bits of w
+ */
+#define MASK_LSBS(w, i) (w & ((~((xen_ulong_t)0UL)) << i))
+
+static inline xen_ulong_t active_evtchns(unsigned int cpu,
+					 struct shared_info *sh,
+					 unsigned int idx)
+{
+	return sh->evtchn_pending[idx] &
+		per_cpu(cpu_evtchn_mask, cpu)[idx] &
+		~sh->evtchn_mask[idx];
+}
+
+/*
+ * Search the CPU''s pending events bitmasks.  For each one found, map
+ * the event number to an irq, and feed it into do_IRQ() for handling.
+ *
+ * Xen uses a two-level bitmap to speed searching.  The first level is
+ * a bitset of words which contain pending event bits.  The second
+ * level is a bitset of pending events themselves.
+ */
+void xen_evtchn_handle_events(int cpu)
+{
+	int irq;
+	xen_ulong_t pending_words;
+	xen_ulong_t pending_bits;
+	int start_word_idx, start_bit_idx;
+	int word_idx, bit_idx;
+	int i;
+	struct irq_desc *desc;
+	struct shared_info *s = HYPERVISOR_shared_info;
+	struct vcpu_info *vcpu_info = __this_cpu_read(xen_vcpu);
+
+	/* Timer interrupt has highest priority. */
+	irq = irq_from_virq(cpu, VIRQ_TIMER);
+	if (irq != -1) {
+		unsigned int evtchn = evtchn_from_irq(irq);
+		word_idx = evtchn / BITS_PER_LONG;
+		bit_idx = evtchn % BITS_PER_LONG;
+		if (active_evtchns(cpu, s, word_idx) & (1ULL << bit_idx)) {
+			desc = irq_to_desc(irq);
+			if (desc)
+				generic_handle_irq_desc(irq, desc);
+		}
+	}
+
+	/*
+	 * Master flag must be cleared /before/ clearing
+	 * selector flag. xchg_xen_ulong must contain an
+	 * appropriate barrier.
+	 */
+	pending_words = xchg_xen_ulong(&vcpu_info->evtchn_pending_sel, 0);
+
+	start_word_idx = __this_cpu_read(current_word_idx);
+	start_bit_idx = __this_cpu_read(current_bit_idx);
+
+	word_idx = start_word_idx;
+
+	for (i = 0; pending_words != 0; i++) {
+		xen_ulong_t words;
+
+		words = MASK_LSBS(pending_words, word_idx);
+
+		/*
+		 * If we masked out all events, wrap to beginning.
+		 */
+		if (words == 0) {
+			word_idx = 0;
+			bit_idx = 0;
+			continue;
+		}
+		word_idx = EVTCHN_FIRST_BIT(words);
+
+		pending_bits = active_evtchns(cpu, s, word_idx);
+		bit_idx = 0; /* usually scan entire word from start */
+		/*
+		 * We scan the starting word in two parts.
+		 *
+		 * 1st time: start in the middle, scanning the
+		 * upper bits.
+		 *
+		 * 2nd time: scan the whole word (not just the
+		 * parts skipped in the first pass) -- if an
+		 * event in the previously scanned bits is
+		 * pending again it would just be scanned on
+		 * the next loop anyway.
+		 */
+		if (word_idx == start_word_idx) {
+			if (i == 0)
+				bit_idx = start_bit_idx;
+		}
+
+		do {
+			xen_ulong_t bits;
+			int port;
+
+			bits = MASK_LSBS(pending_bits, bit_idx);
+
+			/* If we masked out all events, move on. */
+			if (bits == 0)
+				break;
+
+			bit_idx = EVTCHN_FIRST_BIT(bits);
+
+			/* Process port. */
+			port = (word_idx * BITS_PER_EVTCHN_WORD) + bit_idx;
+			irq = evtchn_to_irq[port];
+
+			if (irq != -1) {
+				desc = irq_to_desc(irq);
+				if (desc)
+					generic_handle_irq_desc(irq, desc);
+			}
+
+			bit_idx = (bit_idx + 1) % BITS_PER_EVTCHN_WORD;
+
+			/* Next caller starts at last processed + 1 */
+			__this_cpu_write(current_word_idx,
+					 bit_idx ? word_idx :
+					 (word_idx+1) % BITS_PER_EVTCHN_WORD);
+			__this_cpu_write(current_bit_idx, bit_idx);
+		} while (bit_idx != 0);
+
+		/* Scan start_l1i twice; all others once. */
+		if ((word_idx != start_word_idx) || (i != 0))
+			pending_words &= ~(1UL << word_idx);
+
+		word_idx = (word_idx + 1) % BITS_PER_EVTCHN_WORD;
+	}
+}
+
+irqreturn_t xen_debug_interrupt(int irq, void *dev_id)
+{
+	struct shared_info *sh = HYPERVISOR_shared_info;
+	int cpu = smp_processor_id();
+	xen_ulong_t *cpu_evtchn = per_cpu(cpu_evtchn_mask, cpu);
+	int i;
+	unsigned long flags;
+	static DEFINE_SPINLOCK(debug_lock);
+	struct vcpu_info *v;
+
+	spin_lock_irqsave(&debug_lock, flags);
+
+	printk("\nvcpu %d\n  ", cpu);
+
+	for_each_online_cpu(i) {
+		int pending;
+		v = per_cpu(xen_vcpu, i);
+		pending = (get_irq_regs() && i == cpu)
+			? xen_irqs_disabled(get_irq_regs())
+			: v->evtchn_upcall_mask;
+		printk("%d: masked=%d pending=%d event_sel
%0*"PRI_xen_ulong"\n  ", i,
+		       pending, v->evtchn_upcall_pending,
+		       (int)(sizeof(v->evtchn_pending_sel)*2),
+		       v->evtchn_pending_sel);
+	}
+	v = per_cpu(xen_vcpu, cpu);
+
+	printk("\npending:\n   ");
+	for (i = ARRAY_SIZE(sh->evtchn_pending)-1; i >= 0; i--)
+		printk("%0*"PRI_xen_ulong"%s",
+		       (int)sizeof(sh->evtchn_pending[0])*2,
+		       sh->evtchn_pending[i],
+		       i % 8 == 0 ? "\n   " : " ");
+	printk("\nglobal mask:\n   ");
+	for (i = ARRAY_SIZE(sh->evtchn_mask)-1; i >= 0; i--)
+		printk("%0*"PRI_xen_ulong"%s",
+		       (int)(sizeof(sh->evtchn_mask[0])*2),
+		       sh->evtchn_mask[i],
+		       i % 8 == 0 ? "\n   " : " ");
+
+	printk("\nglobally unmasked:\n   ");
+	for (i = ARRAY_SIZE(sh->evtchn_mask)-1; i >= 0; i--)
+		printk("%0*"PRI_xen_ulong"%s",
+		       (int)(sizeof(sh->evtchn_mask[0])*2),
+		       sh->evtchn_pending[i] & ~sh->evtchn_mask[i],
+		       i % 8 == 0 ? "\n   " : " ");
+
+	printk("\nlocal cpu%d mask:\n   ", cpu);
+	for (i = (NR_EVENT_CHANNELS/BITS_PER_EVTCHN_WORD)-1; i >= 0; i--)
+		printk("%0*"PRI_xen_ulong"%s",
(int)(sizeof(cpu_evtchn[0])*2),
+		       cpu_evtchn[i],
+		       i % 8 == 0 ? "\n   " : " ");
+
+	printk("\nlocally unmasked:\n   ");
+	for (i = ARRAY_SIZE(sh->evtchn_mask)-1; i >= 0; i--) {
+		xen_ulong_t pending = sh->evtchn_pending[i]
+			& ~sh->evtchn_mask[i]
+			& cpu_evtchn[i];
+		printk("%0*"PRI_xen_ulong"%s",
+		       (int)(sizeof(sh->evtchn_mask[0])*2),
+		       pending, i % 8 == 0 ? "\n   " : " ");
+	}
+
+	printk("\npending list:\n");
+	for (i = 0; i < NR_EVENT_CHANNELS; i++) {
+		if (sync_test_bit(i, BM(sh->evtchn_pending))) {
+			int word_idx = i / BITS_PER_EVTCHN_WORD;
+			printk("  %d: event %d -> irq %d%s%s%s\n",
+			       cpu_from_evtchn(i), i,
+			       evtchn_to_irq[i],
+			       sync_test_bit(word_idx, BM(&v->evtchn_pending_sel))
+			       ? "" : " l2-clear",
+			       !sync_test_bit(i, BM(sh->evtchn_mask))
+			       ? "" : " globally-masked",
+			       sync_test_bit(i, BM(cpu_evtchn))
+			       ? "" : " locally-masked");
+		}
+	}
+
+	spin_unlock_irqrestore(&debug_lock, flags);
+
+	return IRQ_HANDLED;
+}
diff --git a/drivers/xen/events/events_base.c b/drivers/xen/events/events_base.c
index fec5da4..8771b74 100644
--- a/drivers/xen/events/events_base.c
+++ b/drivers/xen/events/events_base.c
@@ -59,6 +59,8 @@
 #include <xen/interface/vcpu.h>
 #include <asm/hw_irq.h>
 
+#include "events_internal.h"
+
 /*
  * This lock protects updates to the following mapping and reference-count
  * arrays. The lock does not need to be acquired to read the mapping tables.
@@ -73,72 +75,12 @@ static DEFINE_PER_CPU(int [NR_VIRQS], virq_to_irq) = {[0 ...
NR_VIRQS-1] = -1};
 /* IRQ <-> IPI mapping */
 static DEFINE_PER_CPU(int [XEN_NR_IPIS], ipi_to_irq) = {[0 ... XEN_NR_IPIS-1] =
-1};
 
-/* Interrupt types. */
-enum xen_irq_type {
-	IRQT_UNBOUND = 0,
-	IRQT_PIRQ,
-	IRQT_VIRQ,
-	IRQT_IPI,
-	IRQT_EVTCHN
-};
-
-/*
- * Packed IRQ information:
- * type - enum xen_irq_type
- * event channel - irq->event channel mapping
- * cpu - cpu this event channel is bound to
- * index - type-specific information:
- *    PIRQ - physical IRQ, GSI, flags, and owner domain
- *    VIRQ - virq number
- *    IPI - IPI vector
- *    EVTCHN -
- */
-struct irq_info {
-	struct list_head list;
-	int refcnt;
-	enum xen_irq_type type;	/* type */
-	unsigned irq;
-	unsigned short evtchn;	/* event channel */
-	unsigned short cpu;	/* cpu bound */
-
-	union {
-		unsigned short virq;
-		enum ipi_vector ipi;
-		struct {
-			unsigned short pirq;
-			unsigned short gsi;
-			unsigned char flags;
-			uint16_t domid;
-		} pirq;
-	} u;
-};
-#define PIRQ_NEEDS_EOI	(1 << 0)
-#define PIRQ_SHAREABLE	(1 << 1)
-
-static int *evtchn_to_irq;
+int *evtchn_to_irq;
 #ifdef CONFIG_X86
 static unsigned long *pirq_eoi_map;
 #endif
 static bool (*pirq_needs_eoi)(unsigned irq);
 
-/*
- * Note sizeof(xen_ulong_t) can be more than sizeof(unsigned long). Be
- * careful to only use bitops which allow for this (e.g
- * test_bit/find_first_bit and friends but not __ffs) and to pass
- * BITS_PER_EVTCHN_WORD as the bitmask length.
- */
-#define BITS_PER_EVTCHN_WORD (sizeof(xen_ulong_t)*8)
-/*
- * Make a bitmask (i.e. unsigned long *) of a xen_ulong_t
- * array. Primarily to avoid long lines (hence the terse name).
- */
-#define BM(x) (unsigned long *)(x)
-/* Find the first set bit in a evtchn mask */
-#define EVTCHN_FIRST_BIT(w) find_first_bit(BM(&(w)), BITS_PER_EVTCHN_WORD)
-
-static DEFINE_PER_CPU(xen_ulong_t [NR_EVENT_CHANNELS/BITS_PER_EVTCHN_WORD],
-		      cpu_evtchn_mask);
-
 /* Xen will never allocate port zero for any purpose. */
 #define VALID_EVTCHN(chn)	((chn) != 0)
 
@@ -149,7 +91,7 @@ static void enable_dynirq(struct irq_data *data);
 static void disable_dynirq(struct irq_data *data);
 
 /* Get info for IRQ */
-static struct irq_info *info_for_irq(unsigned irq)
+struct irq_info *info_for_irq(unsigned irq)
 {
 	return irq_get_handler_data(irq);
 }
@@ -230,7 +172,7 @@ static void xen_irq_info_pirq_init(unsigned irq,
 /*
  * Accessors for packed IRQ information.
  */
-static unsigned int evtchn_from_irq(unsigned irq)
+unsigned int evtchn_from_irq(unsigned irq)
 {
 	if (unlikely(WARN(irq < 0 || irq >= nr_irqs, "Invalid irq
%d!\n", irq)))
 		return 0;
@@ -244,6 +186,11 @@ unsigned irq_from_evtchn(unsigned int evtchn)
 }
 EXPORT_SYMBOL_GPL(irq_from_evtchn);
 
+int irq_from_virq(unsigned int cpu, unsigned int virq)
+{
+	return per_cpu(virq_to_irq, cpu)[virq];
+}
+
 static enum ipi_vector ipi_from_irq(unsigned irq)
 {
 	struct irq_info *info = info_for_irq(irq);
@@ -279,12 +226,12 @@ static enum xen_irq_type type_from_irq(unsigned irq)
 	return info_for_irq(irq)->type;
 }
 
-static unsigned cpu_from_irq(unsigned irq)
+unsigned cpu_from_irq(unsigned irq)
 {
 	return info_for_irq(irq)->cpu;
 }
 
-static unsigned int cpu_from_evtchn(unsigned int evtchn)
+unsigned int cpu_from_evtchn(unsigned int evtchn)
 {
 	int irq = evtchn_to_irq[evtchn];
 	unsigned ret = 0;
@@ -310,55 +257,21 @@ static bool pirq_needs_eoi_flag(unsigned irq)
 	return info->u.pirq.flags & PIRQ_NEEDS_EOI;
 }
 
-static inline xen_ulong_t active_evtchns(unsigned int cpu,
-					 struct shared_info *sh,
-					 unsigned int idx)
-{
-	return sh->evtchn_pending[idx] &
-		per_cpu(cpu_evtchn_mask, cpu)[idx] &
-		~sh->evtchn_mask[idx];
-}
-
 static void bind_evtchn_to_cpu(unsigned int chn, unsigned int cpu)
 {
 	int irq = evtchn_to_irq[chn];
+	struct irq_info *info = info_for_irq(irq);
 
 	BUG_ON(irq == -1);
 #ifdef CONFIG_SMP
 	cpumask_copy(irq_to_desc(irq)->irq_data.affinity, cpumask_of(cpu));
 #endif
 
-	clear_bit(chn, BM(per_cpu(cpu_evtchn_mask, cpu_from_irq(irq))));
-	set_bit(chn, BM(per_cpu(cpu_evtchn_mask, cpu)));
+	xen_evtchn_port_bind_to_cpu(info, cpu);
 
-	info_for_irq(irq)->cpu = cpu;
-}
-
-static inline void clear_evtchn(int port)
-{
-	struct shared_info *s = HYPERVISOR_shared_info;
-	sync_clear_bit(port, BM(&s->evtchn_pending[0]));
-}
-
-static inline void set_evtchn(int port)
-{
-	struct shared_info *s = HYPERVISOR_shared_info;
-	sync_set_bit(port, BM(&s->evtchn_pending[0]));
-}
-
-static inline int test_evtchn(int port)
-{
-	struct shared_info *s = HYPERVISOR_shared_info;
-	return sync_test_bit(port, BM(&s->evtchn_pending[0]));
-}
-
-static inline int test_and_set_mask(int port)
-{
-	struct shared_info *s = HYPERVISOR_shared_info;
-	return sync_test_and_set_bit(port, BM(&s->evtchn_mask[0]));
+	info->cpu = cpu;
 }
 
-
 /**
  * notify_remote_via_irq - send event to remote end of event channel via irq
  * @irq: irq of event channel to send event to
@@ -376,63 +289,6 @@ void notify_remote_via_irq(int irq)
 }
 EXPORT_SYMBOL_GPL(notify_remote_via_irq);
 
-static void mask_evtchn(int port)
-{
-	struct shared_info *s = HYPERVISOR_shared_info;
-	sync_set_bit(port, BM(&s->evtchn_mask[0]));
-}
-
-static void unmask_evtchn(int port)
-{
-	struct shared_info *s = HYPERVISOR_shared_info;
-	unsigned int cpu = get_cpu();
-	int do_hypercall = 0, evtchn_pending = 0;
-
-	BUG_ON(!irqs_disabled());
-
-	if (unlikely((cpu != cpu_from_evtchn(port))))
-		do_hypercall = 1;
-	else {
-		/*
-		 * Need to clear the mask before checking pending to
-		 * avoid a race with an event becoming pending.
-		 *
-		 * EVTCHNOP_unmask will only trigger an upcall if the
-		 * mask bit was set, so if a hypercall is needed
-		 * remask the event.
-		 */
-		sync_clear_bit(port, BM(&s->evtchn_mask[0]));
-		evtchn_pending = sync_test_bit(port, BM(&s->evtchn_pending[0]));
-
-		if (unlikely(evtchn_pending && xen_hvm_domain())) {
-			sync_set_bit(port, BM(&s->evtchn_mask[0]));
-			do_hypercall = 1;
-		}
-	}
-
-	/* Slow path (hypercall) if this is a non-local port or if this is
-	 * an hvm domain and an event is pending (hvm domains don''t have
-	 * their own implementation of irq_enable). */
-	if (do_hypercall) {
-		struct evtchn_unmask unmask = { .port = port };
-		(void)HYPERVISOR_event_channel_op(EVTCHNOP_unmask, &unmask);
-	} else {
-		struct vcpu_info *vcpu_info = __this_cpu_read(xen_vcpu);
-
-		/*
-		 * The following is basically the equivalent of
-		 * ''hw_resend_irq''. Just like a real IO-APIC we
''lose
-		 * the interrupt edge'' if the channel is masked.
-		 */
-		if (evtchn_pending &&
-		    !sync_test_and_set_bit(port / BITS_PER_EVTCHN_WORD,
-					   BM(&vcpu_info->evtchn_pending_sel)))
-			vcpu_info->evtchn_upcall_pending = 1;
-	}
-
-	put_cpu();
-}
-
 static void xen_irq_init(unsigned irq)
 {
 	struct irq_info *info;
@@ -1216,222 +1072,21 @@ void xen_send_IPI_one(unsigned int cpu, enum ipi_vector
vector)
 	notify_remote_via_irq(irq);
 }
 
-irqreturn_t xen_debug_interrupt(int irq, void *dev_id)
-{
-	struct shared_info *sh = HYPERVISOR_shared_info;
-	int cpu = smp_processor_id();
-	xen_ulong_t *cpu_evtchn = per_cpu(cpu_evtchn_mask, cpu);
-	int i;
-	unsigned long flags;
-	static DEFINE_SPINLOCK(debug_lock);
-	struct vcpu_info *v;
-
-	spin_lock_irqsave(&debug_lock, flags);
-
-	printk("\nvcpu %d\n  ", cpu);
-
-	for_each_online_cpu(i) {
-		int pending;
-		v = per_cpu(xen_vcpu, i);
-		pending = (get_irq_regs() && i == cpu)
-			? xen_irqs_disabled(get_irq_regs())
-			: v->evtchn_upcall_mask;
-		printk("%d: masked=%d pending=%d event_sel
%0*"PRI_xen_ulong"\n  ", i,
-		       pending, v->evtchn_upcall_pending,
-		       (int)(sizeof(v->evtchn_pending_sel)*2),
-		       v->evtchn_pending_sel);
-	}
-	v = per_cpu(xen_vcpu, cpu);
-
-	printk("\npending:\n   ");
-	for (i = ARRAY_SIZE(sh->evtchn_pending)-1; i >= 0; i--)
-		printk("%0*"PRI_xen_ulong"%s",
-		       (int)sizeof(sh->evtchn_pending[0])*2,
-		       sh->evtchn_pending[i],
-		       i % 8 == 0 ? "\n   " : " ");
-	printk("\nglobal mask:\n   ");
-	for (i = ARRAY_SIZE(sh->evtchn_mask)-1; i >= 0; i--)
-		printk("%0*"PRI_xen_ulong"%s",
-		       (int)(sizeof(sh->evtchn_mask[0])*2),
-		       sh->evtchn_mask[i],
-		       i % 8 == 0 ? "\n   " : " ");
-
-	printk("\nglobally unmasked:\n   ");
-	for (i = ARRAY_SIZE(sh->evtchn_mask)-1; i >= 0; i--)
-		printk("%0*"PRI_xen_ulong"%s",
-		       (int)(sizeof(sh->evtchn_mask[0])*2),
-		       sh->evtchn_pending[i] & ~sh->evtchn_mask[i],
-		       i % 8 == 0 ? "\n   " : " ");
-
-	printk("\nlocal cpu%d mask:\n   ", cpu);
-	for (i = (NR_EVENT_CHANNELS/BITS_PER_EVTCHN_WORD)-1; i >= 0; i--)
-		printk("%0*"PRI_xen_ulong"%s",
(int)(sizeof(cpu_evtchn[0])*2),
-		       cpu_evtchn[i],
-		       i % 8 == 0 ? "\n   " : " ");
-
-	printk("\nlocally unmasked:\n   ");
-	for (i = ARRAY_SIZE(sh->evtchn_mask)-1; i >= 0; i--) {
-		xen_ulong_t pending = sh->evtchn_pending[i]
-			& ~sh->evtchn_mask[i]
-			& cpu_evtchn[i];
-		printk("%0*"PRI_xen_ulong"%s",
-		       (int)(sizeof(sh->evtchn_mask[0])*2),
-		       pending, i % 8 == 0 ? "\n   " : " ");
-	}
-
-	printk("\npending list:\n");
-	for (i = 0; i < NR_EVENT_CHANNELS; i++) {
-		if (sync_test_bit(i, BM(sh->evtchn_pending))) {
-			int word_idx = i / BITS_PER_EVTCHN_WORD;
-			printk("  %d: event %d -> irq %d%s%s%s\n",
-			       cpu_from_evtchn(i), i,
-			       evtchn_to_irq[i],
-			       sync_test_bit(word_idx, BM(&v->evtchn_pending_sel))
-					     ? "" : " l2-clear",
-			       !sync_test_bit(i, BM(sh->evtchn_mask))
-					     ? "" : " globally-masked",
-			       sync_test_bit(i, BM(cpu_evtchn))
-					     ? "" : " locally-masked");
-		}
-	}
-
-	spin_unlock_irqrestore(&debug_lock, flags);
-
-	return IRQ_HANDLED;
-}
-
 static DEFINE_PER_CPU(unsigned, xed_nesting_count);
-static DEFINE_PER_CPU(unsigned int, current_word_idx);
-static DEFINE_PER_CPU(unsigned int, current_bit_idx);
 
-/*
- * Mask out the i least significant bits of w
- */
-#define MASK_LSBS(w, i) (w & ((~((xen_ulong_t)0UL)) << i))
-
-/*
- * Search the CPUs pending events bitmasks.  For each one found, map
- * the event number to an irq, and feed it into do_IRQ() for
- * handling.
- *
- * Xen uses a two-level bitmap to speed searching.  The first level is
- * a bitset of words which contain pending event bits.  The second
- * level is a bitset of pending events themselves.
- */
 static void __xen_evtchn_do_upcall(void)
 {
-	int start_word_idx, start_bit_idx;
-	int word_idx, bit_idx;
-	int i, irq;
-	int cpu = get_cpu();
-	struct shared_info *s = HYPERVISOR_shared_info;
 	struct vcpu_info *vcpu_info = __this_cpu_read(xen_vcpu);
+	int cpu = get_cpu();
 	unsigned count;
 
 	do {
-		xen_ulong_t pending_words;
-		xen_ulong_t pending_bits;
-		struct irq_desc *desc;
-
 		vcpu_info->evtchn_upcall_pending = 0;
 
 		if (__this_cpu_inc_return(xed_nesting_count) - 1)
 			goto out;
 
-		/*
-		 * Master flag must be cleared /before/ clearing
-		 * selector flag. xchg_xen_ulong must contain an
-		 * appropriate barrier.
-		 */
-		if ((irq = per_cpu(virq_to_irq, cpu)[VIRQ_TIMER]) != -1) {
-			int evtchn = evtchn_from_irq(irq);
-			word_idx = evtchn / BITS_PER_LONG;
-			pending_bits = evtchn % BITS_PER_LONG;
-			if (active_evtchns(cpu, s, word_idx) & (1ULL << pending_bits)) {
-				desc = irq_to_desc(irq);
-				if (desc)
-					generic_handle_irq_desc(irq, desc);
-			}
-		}
-
-		pending_words = xchg_xen_ulong(&vcpu_info->evtchn_pending_sel, 0);
-
-		start_word_idx = __this_cpu_read(current_word_idx);
-		start_bit_idx = __this_cpu_read(current_bit_idx);
-
-		word_idx = start_word_idx;
-
-		for (i = 0; pending_words != 0; i++) {
-			xen_ulong_t words;
-
-			words = MASK_LSBS(pending_words, word_idx);
-
-			/*
-			 * If we masked out all events, wrap to beginning.
-			 */
-			if (words == 0) {
-				word_idx = 0;
-				bit_idx = 0;
-				continue;
-			}
-			word_idx = EVTCHN_FIRST_BIT(words);
-
-			pending_bits = active_evtchns(cpu, s, word_idx);
-			bit_idx = 0; /* usually scan entire word from start */
-			/*
-			 * We scan the starting word in two parts.
-			 *
-			 * 1st time: start in the middle, scanning the
-			 * upper bits.
-			 *
-			 * 2nd time: scan the whole word (not just the
-			 * parts skipped in the first pass) -- if an
-			 * event in the previously scanned bits is
-			 * pending again it would just be scanned on
-			 * the next loop anyway.
-			 */
-			if (word_idx == start_word_idx) {
-				if (i == 0)
-					bit_idx = start_bit_idx;
-			}
-
-			do {
-				xen_ulong_t bits;
-				int port;
-
-				bits = MASK_LSBS(pending_bits, bit_idx);
-
-				/* If we masked out all events, move on. */
-				if (bits == 0)
-					break;
-
-				bit_idx = EVTCHN_FIRST_BIT(bits);
-
-				/* Process port. */
-				port = (word_idx * BITS_PER_EVTCHN_WORD) + bit_idx;
-				irq = evtchn_to_irq[port];
-
-				if (irq != -1) {
-					desc = irq_to_desc(irq);
-					if (desc)
-						generic_handle_irq_desc(irq, desc);
-				}
-
-				bit_idx = (bit_idx + 1) % BITS_PER_EVTCHN_WORD;
-
-				/* Next caller starts at last processed + 1 */
-				__this_cpu_write(current_word_idx,
-						 bit_idx ? word_idx :
-						 (word_idx+1) % BITS_PER_EVTCHN_WORD);
-				__this_cpu_write(current_bit_idx, bit_idx);
-			} while (bit_idx != 0);
-
-			/* Scan start_l1i twice; all others once. */
-			if ((word_idx != start_word_idx) || (i != 0))
-				pending_words &= ~(1UL << word_idx);
-
-			word_idx = (word_idx + 1) % BITS_PER_EVTCHN_WORD;
-		}
+		xen_evtchn_handle_events(cpu);
 
 		BUG_ON(!irqs_disabled());
 
diff --git a/drivers/xen/events/events_internal.h
b/drivers/xen/events/events_internal.h
new file mode 100644
index 0000000..79ac70b
--- /dev/null
+++ b/drivers/xen/events/events_internal.h
@@ -0,0 +1,74 @@
+/*
+ * Xen Event Channels (internal header)
+ *
+ * Copyright (C) 2013 Citrix Systems R&D Ltd.
+ *
+ * This source code is licensed under the GNU General Public License,
+ * Version 2 or later.  See the file COPYING for more details.
+ */
+#ifndef __EVENTS_INTERNAL_H__
+#define __EVENTS_INTERNAL_H__
+
+/* Interrupt types. */
+enum xen_irq_type {
+	IRQT_UNBOUND = 0,
+	IRQT_PIRQ,
+	IRQT_VIRQ,
+	IRQT_IPI,
+	IRQT_EVTCHN
+};
+
+/*
+ * Packed IRQ information:
+ * type - enum xen_irq_type
+ * event channel - irq->event channel mapping
+ * cpu - cpu this event channel is bound to
+ * index - type-specific information:
+ *    PIRQ - vector, with MSB being "needs EIO", or physical IRQ of
the HVM
+ *           guest, or GSI (real passthrough IRQ) of the device.
+ *    VIRQ - virq number
+ *    IPI - IPI vector
+ *    EVTCHN -
+ */
+struct irq_info {
+	struct list_head list;
+	int refcnt;
+	enum xen_irq_type type;	/* type */
+	unsigned irq;
+	unsigned short evtchn;	/* event channel */
+	unsigned short cpu;	/* cpu bound */
+
+	union {
+		unsigned short virq;
+		enum ipi_vector ipi;
+		struct {
+			unsigned short pirq;
+			unsigned short gsi;
+			unsigned char vector;
+			unsigned char flags;
+			uint16_t domid;
+		} pirq;
+	} u;
+};
+
+#define PIRQ_NEEDS_EOI	(1 << 0)
+#define PIRQ_SHAREABLE	(1 << 1)
+
+extern int *evtchn_to_irq;
+
+struct irq_info *info_for_irq(unsigned irq);
+unsigned cpu_from_irq(unsigned irq);
+unsigned cpu_from_evtchn(unsigned int evtchn);
+
+void xen_evtchn_port_bind_to_cpu(struct irq_info *info, int cpu);
+
+void clear_evtchn(int port);
+void set_evtchn(int port);
+int test_evtchn(int port);
+int test_and_set_mask(int port);
+void mask_evtchn(int port);
+void unmask_evtchn(int port);
+
+void xen_evtchn_handle_events(int cpu);
+
+#endif /* #ifndef __EVENTS_INTERNAL_H__ */
diff --git a/include/xen/events.h b/include/xen/events.h
index c9ea10e..32ae0f2 100644
--- a/include/xen/events.h
+++ b/include/xen/events.h
@@ -73,6 +73,8 @@ void xen_poll_irq_timeout(int irq, u64 timeout);
 
 /* Determine the IRQ which is bound to an event channel */
 unsigned irq_from_evtchn(unsigned int evtchn);
+int irq_from_virq(unsigned int cpu, unsigned int virq);
+unsigned int evtchn_from_irq(unsigned irq);
 
 /* Xen HVM evtchn vector callback */
 void xen_hvm_callback_vector(void);
-- 
1.7.2.5

From: David Vrabel <david.vrabel@citrix.com>

evtchn_ops contains the low-level operations that access the shared
data structures.  This allows alternate ABIs to be supported.

Signed-off-by: David Vrabel <david.vrabel@citrix.com>
Reviewed-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
---
 drivers/xen/events/events_2l.c       |   33 +++++++++++++----
 drivers/xen/events/events_base.c     |    4 ++
 drivers/xen/events/events_internal.h |   63 +++++++++++++++++++++++++++++----
 3 files changed, 84 insertions(+), 16 deletions(-)

diff --git a/drivers/xen/events/events_2l.c b/drivers/xen/events/events_2l.c
index a77e98d..e55677c 100644
--- a/drivers/xen/events/events_2l.c
+++ b/drivers/xen/events/events_2l.c
@@ -41,43 +41,43 @@
 static DEFINE_PER_CPU(xen_ulong_t [NR_EVENT_CHANNELS/BITS_PER_EVTCHN_WORD],
 		      cpu_evtchn_mask);
 
-void xen_evtchn_port_bind_to_cpu(struct irq_info *info, int cpu)
+static void evtchn_2l_bind_to_cpu(struct irq_info *info, unsigned cpu)
 {
 	clear_bit(info->evtchn, BM(per_cpu(cpu_evtchn_mask, info->cpu)));
 	set_bit(info->evtchn, BM(per_cpu(cpu_evtchn_mask, cpu)));
 }
 
-void clear_evtchn(int port)
+static void evtchn_2l_clear_pending(unsigned port)
 {
 	struct shared_info *s = HYPERVISOR_shared_info;
 	sync_clear_bit(port, BM(&s->evtchn_pending[0]));
 }
 
-void set_evtchn(int port)
+static void evtchn_2l_set_pending(unsigned port)
 {
 	struct shared_info *s = HYPERVISOR_shared_info;
 	sync_set_bit(port, BM(&s->evtchn_pending[0]));
 }
 
-int test_evtchn(int port)
+static bool evtchn_2l_is_pending(unsigned port)
 {
 	struct shared_info *s = HYPERVISOR_shared_info;
 	return sync_test_bit(port, BM(&s->evtchn_pending[0]));
 }
 
-int test_and_set_mask(int port)
+static bool evtchn_2l_test_and_set_mask(unsigned port)
 {
 	struct shared_info *s = HYPERVISOR_shared_info;
 	return sync_test_and_set_bit(port, BM(&s->evtchn_mask[0]));
 }
 
-void mask_evtchn(int port)
+static void evtchn_2l_mask(unsigned port)
 {
 	struct shared_info *s = HYPERVISOR_shared_info;
 	sync_set_bit(port, BM(&s->evtchn_mask[0]));
 }
 
-void unmask_evtchn(int port)
+static void evtchn_2l_unmask(unsigned port)
 {
 	struct shared_info *s = HYPERVISOR_shared_info;
 	unsigned int cpu = get_cpu();
@@ -153,7 +153,7 @@ static inline xen_ulong_t active_evtchns(unsigned int cpu,
  * a bitset of words which contain pending event bits.  The second
  * level is a bitset of pending events themselves.
  */
-void xen_evtchn_handle_events(int cpu)
+static void evtchn_2l_handle_events(unsigned cpu)
 {
 	int irq;
 	xen_ulong_t pending_words;
@@ -346,3 +346,20 @@ irqreturn_t xen_debug_interrupt(int irq, void *dev_id)
 
 	return IRQ_HANDLED;
 }
+
+static const struct evtchn_ops evtchn_ops_2l = {
+	.bind_to_cpu       = evtchn_2l_bind_to_cpu,
+	.clear_pending     = evtchn_2l_clear_pending,
+	.set_pending       = evtchn_2l_set_pending,
+	.is_pending        = evtchn_2l_is_pending,
+	.test_and_set_mask = evtchn_2l_test_and_set_mask,
+	.mask              = evtchn_2l_mask,
+	.unmask            = evtchn_2l_unmask,
+	.handle_events     = evtchn_2l_handle_events,
+};
+
+void __init xen_evtchn_2l_init(void)
+{
+	pr_info("Using 2-level ABI\n");
+	evtchn_ops = &evtchn_ops_2l;
+}
diff --git a/drivers/xen/events/events_base.c b/drivers/xen/events/events_base.c
index 8771b74..7c7b744 100644
--- a/drivers/xen/events/events_base.c
+++ b/drivers/xen/events/events_base.c
@@ -61,6 +61,8 @@
 
 #include "events_internal.h"
 
+const struct evtchn_ops *evtchn_ops;
+
 /*
  * This lock protects updates to the following mapping and reference-count
  * arrays. The lock does not need to be acquired to read the mapping tables.
@@ -1523,6 +1525,8 @@ void __init xen_init_IRQ(void)
 {
 	int i;
 
+	xen_evtchn_2l_init();
+
 	evtchn_to_irq = kcalloc(NR_EVENT_CHANNELS, sizeof(*evtchn_to_irq),
 				    GFP_KERNEL);
 	BUG_ON(!evtchn_to_irq);
diff --git a/drivers/xen/events/events_internal.h
b/drivers/xen/events/events_internal.h
index 79ac70b..ba8142f 100644
--- a/drivers/xen/events/events_internal.h
+++ b/drivers/xen/events/events_internal.h
@@ -54,21 +54,68 @@ struct irq_info {
 #define PIRQ_NEEDS_EOI	(1 << 0)
 #define PIRQ_SHAREABLE	(1 << 1)
 
+struct evtchn_ops {
+	void (*bind_to_cpu)(struct irq_info *info, unsigned cpu);
+
+	void (*clear_pending)(unsigned port);
+	void (*set_pending)(unsigned port);
+	bool (*is_pending)(unsigned port);
+	bool (*test_and_set_mask)(unsigned port);
+	void (*mask)(unsigned port);
+	void (*unmask)(unsigned port);
+
+	void (*handle_events)(unsigned cpu);
+};
+
+extern const struct evtchn_ops *evtchn_ops;
+
 extern int *evtchn_to_irq;
 
 struct irq_info *info_for_irq(unsigned irq);
 unsigned cpu_from_irq(unsigned irq);
 unsigned cpu_from_evtchn(unsigned int evtchn);
 
-void xen_evtchn_port_bind_to_cpu(struct irq_info *info, int cpu);
+static inline void xen_evtchn_port_bind_to_cpu(struct irq_info *info,
+					       unsigned cpu)
+{
+	evtchn_ops->bind_to_cpu(info, cpu);
+}
+
+static inline void clear_evtchn(unsigned port)
+{
+	evtchn_ops->clear_pending(port);
+}
+
+static inline void set_evtchn(unsigned port)
+{
+	evtchn_ops->set_pending(port);
+}
+
+static inline bool test_evtchn(unsigned port)
+{
+	return evtchn_ops->is_pending(port);
+}
+
+static inline bool test_and_set_mask(unsigned port)
+{
+	return evtchn_ops->test_and_set_mask(port);
+}
+
+static inline void mask_evtchn(unsigned port)
+{
+	return evtchn_ops->mask(port);
+}
+
+static inline void unmask_evtchn(unsigned port)
+{
+	return evtchn_ops->unmask(port);
+}
 
-void clear_evtchn(int port);
-void set_evtchn(int port);
-int test_evtchn(int port);
-int test_and_set_mask(int port);
-void mask_evtchn(int port);
-void unmask_evtchn(int port);
+static inline void xen_evtchn_handle_events(unsigned cpu)
+{
+	return evtchn_ops->handle_events(cpu);
+}
 
-void xen_evtchn_handle_events(int cpu);
+void xen_evtchn_2l_init(void);
 
 #endif /* #ifndef __EVENTS_INTERNAL_H__ */
-- 
1.7.2.5

From: David Vrabel <david.vrabel@citrix.com>

The FIFO-based event ABI requires additional setup of newly bound
events (it may need to expand the event array) and this setup may
fail.

xen_irq_info_common_init() is a useful place to put this setup so
allow this call to fail.  This call and the other similar calls are
renamed to be *_setup() to reflect that they may now fail.

This failure can only occur with new event channels not on rebind.

Signed-off-by: David Vrabel <david.vrabel@citrix.com>
Reviewed-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
---
 drivers/xen/events/events_base.c |  156 ++++++++++++++++++++++----------------
 1 files changed, 91 insertions(+), 65 deletions(-)

diff --git a/drivers/xen/events/events_base.c b/drivers/xen/events/events_base.c
index 7c7b744..4f7d94a 100644
--- a/drivers/xen/events/events_base.c
+++ b/drivers/xen/events/events_base.c
@@ -99,7 +99,7 @@ struct irq_info *info_for_irq(unsigned irq)
 }
 
 /* Constructors for packed IRQ information. */
-static void xen_irq_info_common_init(struct irq_info *info,
+static int xen_irq_info_common_setup(struct irq_info *info,
 				     unsigned irq,
 				     enum xen_irq_type type,
 				     unsigned short evtchn,
@@ -116,45 +116,47 @@ static void xen_irq_info_common_init(struct irq_info
*info,
 	evtchn_to_irq[evtchn] = irq;
 
 	irq_clear_status_flags(irq, IRQ_NOREQUEST|IRQ_NOAUTOEN);
+
+	return 0;
 }
 
-static void xen_irq_info_evtchn_init(unsigned irq,
+static int xen_irq_info_evtchn_setup(unsigned irq,
 				     unsigned short evtchn)
 {
 	struct irq_info *info = info_for_irq(irq);
 
-	xen_irq_info_common_init(info, irq, IRQT_EVTCHN, evtchn, 0);
+	return xen_irq_info_common_setup(info, irq, IRQT_EVTCHN, evtchn, 0);
 }
 
-static void xen_irq_info_ipi_init(unsigned cpu,
+static int xen_irq_info_ipi_setup(unsigned cpu,
 				  unsigned irq,
 				  unsigned short evtchn,
 				  enum ipi_vector ipi)
 {
 	struct irq_info *info = info_for_irq(irq);
 
-	xen_irq_info_common_init(info, irq, IRQT_IPI, evtchn, 0);
-
 	info->u.ipi = ipi;
 
 	per_cpu(ipi_to_irq, cpu)[ipi] = irq;
+
+	return xen_irq_info_common_setup(info, irq, IRQT_IPI, evtchn, 0);
 }
 
-static void xen_irq_info_virq_init(unsigned cpu,
+static int xen_irq_info_virq_setup(unsigned cpu,
 				   unsigned irq,
 				   unsigned short evtchn,
 				   unsigned short virq)
 {
 	struct irq_info *info = info_for_irq(irq);
 
-	xen_irq_info_common_init(info, irq, IRQT_VIRQ, evtchn, 0);
-
 	info->u.virq = virq;
 
 	per_cpu(virq_to_irq, cpu)[virq] = irq;
+
+	return xen_irq_info_common_setup(info, irq, IRQT_VIRQ, evtchn, 0);
 }
 
-static void xen_irq_info_pirq_init(unsigned irq,
+static int xen_irq_info_pirq_setup(unsigned irq,
 				   unsigned short evtchn,
 				   unsigned short pirq,
 				   unsigned short gsi,
@@ -163,12 +165,12 @@ static void xen_irq_info_pirq_init(unsigned irq,
 {
 	struct irq_info *info = info_for_irq(irq);
 
-	xen_irq_info_common_init(info, irq, IRQT_PIRQ, evtchn, 0);
-
 	info->u.pirq.pirq = pirq;
 	info->u.pirq.gsi = gsi;
 	info->u.pirq.domid = domid;
 	info->u.pirq.flags = flags;
+
+	return xen_irq_info_common_setup(info, irq, IRQT_PIRQ, evtchn, 0);
 }
 
 /*
@@ -521,6 +523,47 @@ int xen_irq_from_gsi(unsigned gsi)
 }
 EXPORT_SYMBOL_GPL(xen_irq_from_gsi);
 
+static void __unbind_from_irq(unsigned int irq)
+{
+	struct evtchn_close close;
+	int evtchn = evtchn_from_irq(irq);
+	struct irq_info *info = irq_get_handler_data(irq);
+
+	if (info->refcnt > 0) {
+		info->refcnt--;
+		if (info->refcnt != 0)
+			return;
+	}
+
+	if (VALID_EVTCHN(evtchn)) {
+		close.port = evtchn;
+		if (HYPERVISOR_event_channel_op(EVTCHNOP_close, &close) != 0)
+			BUG();
+
+		switch (type_from_irq(irq)) {
+		case IRQT_VIRQ:
+			per_cpu(virq_to_irq, cpu_from_evtchn(evtchn))
+				[virq_from_irq(irq)] = -1;
+			break;
+		case IRQT_IPI:
+			per_cpu(ipi_to_irq, cpu_from_evtchn(evtchn))
+				[ipi_from_irq(irq)] = -1;
+			break;
+		default:
+			break;
+		}
+
+		/* Closed ports are implicitly re-bound to VCPU0. */
+		bind_evtchn_to_cpu(evtchn, 0);
+
+		evtchn_to_irq[evtchn] = -1;
+	}
+
+	BUG_ON(info_for_irq(irq)->type == IRQT_UNBOUND);
+
+	xen_free_irq(irq);
+}
+
 /*
  * Do not make any assumptions regarding the relationship between the
  * IRQ number returned here and the Xen pirq argument.
@@ -536,6 +579,7 @@ int xen_bind_pirq_gsi_to_irq(unsigned gsi,
 {
 	int irq = -1;
 	struct physdev_irq irq_op;
+	int ret;
 
 	mutex_lock(&irq_mapping_update_lock);
 
@@ -563,8 +607,13 @@ int xen_bind_pirq_gsi_to_irq(unsigned gsi,
 		goto out;
 	}
 
-	xen_irq_info_pirq_init(irq, 0, pirq, gsi, DOMID_SELF,
+	ret = xen_irq_info_pirq_setup(irq, 0, pirq, gsi, DOMID_SELF,
 			       shareable ? PIRQ_SHAREABLE : 0);
+	if (ret < 0) {
+		__unbind_from_irq(irq);
+		irq = ret;
+		goto out;
+	}
 
 	pirq_query_unmask(irq);
 	/* We try to use the handler with the appropriate semantic for the
@@ -624,7 +673,9 @@ int xen_bind_pirq_msi_to_irq(struct pci_dev *dev, struct
msi_desc *msidesc,
 	irq_set_chip_and_handler_name(irq, &xen_pirq_chip, handle_edge_irq,
 			name);
 
-	xen_irq_info_pirq_init(irq, 0, pirq, 0, domid, 0);
+	ret = xen_irq_info_pirq_setup(irq, 0, pirq, 0, domid, 0);
+	if (ret < 0)
+		goto error_irq;
 	ret = irq_set_msi_desc(irq, msidesc);
 	if (ret < 0)
 		goto error_irq;
@@ -632,8 +683,8 @@ out:
 	mutex_unlock(&irq_mapping_update_lock);
 	return irq;
 error_irq:
+	__unbind_from_irq(irq);
 	mutex_unlock(&irq_mapping_update_lock);
-	xen_free_irq(irq);
 	return ret;
 }
 #endif
@@ -703,9 +754,11 @@ int xen_pirq_from_irq(unsigned irq)
 	return pirq_from_irq(irq);
 }
 EXPORT_SYMBOL_GPL(xen_pirq_from_irq);
+
 int bind_evtchn_to_irq(unsigned int evtchn)
 {
 	int irq;
+	int ret;
 
 	mutex_lock(&irq_mapping_update_lock);
 
@@ -719,7 +772,12 @@ int bind_evtchn_to_irq(unsigned int evtchn)
 		irq_set_chip_and_handler_name(irq, &xen_dynamic_chip,
 					      handle_edge_irq, "event");
 
-		xen_irq_info_evtchn_init(irq, evtchn);
+		ret = xen_irq_info_evtchn_setup(irq, evtchn);
+		if (ret < 0) {
+			__unbind_from_irq(irq);
+			irq = ret;
+			goto out;
+		}
 	} else {
 		struct irq_info *info = info_for_irq(irq);
 		WARN_ON(info == NULL || info->type != IRQT_EVTCHN);
@@ -736,6 +794,7 @@ static int bind_ipi_to_irq(unsigned int ipi, unsigned int
cpu)
 {
 	struct evtchn_bind_ipi bind_ipi;
 	int evtchn, irq;
+	int ret;
 
 	mutex_lock(&irq_mapping_update_lock);
 
@@ -755,8 +814,12 @@ static int bind_ipi_to_irq(unsigned int ipi, unsigned int
cpu)
 			BUG();
 		evtchn = bind_ipi.port;
 
-		xen_irq_info_ipi_init(cpu, irq, evtchn, ipi);
-
+		ret = xen_irq_info_ipi_setup(cpu, irq, evtchn, ipi);
+		if (ret < 0) {
+			__unbind_from_irq(irq);
+			irq = ret;
+			goto out;
+		}
 		bind_evtchn_to_cpu(evtchn, cpu);
 	} else {
 		struct irq_info *info = info_for_irq(irq);
@@ -835,7 +898,12 @@ int bind_virq_to_irq(unsigned int virq, unsigned int cpu)
 			evtchn = ret;
 		}
 
-		xen_irq_info_virq_init(cpu, irq, evtchn, virq);
+		ret = xen_irq_info_virq_setup(cpu, irq, evtchn, virq);
+		if (ret < 0) {
+			__unbind_from_irq(irq);
+			irq = ret;
+			goto out;
+		}
 
 		bind_evtchn_to_cpu(evtchn, cpu);
 	} else {
@@ -851,50 +919,8 @@ out:
 
 static void unbind_from_irq(unsigned int irq)
 {
-	struct evtchn_close close;
-	int evtchn = evtchn_from_irq(irq);
-	struct irq_info *info = irq_get_handler_data(irq);
-
-	if (WARN_ON(!info))
-		return;
-
 	mutex_lock(&irq_mapping_update_lock);
-
-	if (info->refcnt > 0) {
-		info->refcnt--;
-		if (info->refcnt != 0)
-			goto done;
-	}
-
-	if (VALID_EVTCHN(evtchn)) {
-		close.port = evtchn;
-		if (HYPERVISOR_event_channel_op(EVTCHNOP_close, &close) != 0)
-			BUG();
-
-		switch (type_from_irq(irq)) {
-		case IRQT_VIRQ:
-			per_cpu(virq_to_irq, cpu_from_evtchn(evtchn))
-				[virq_from_irq(irq)] = -1;
-			break;
-		case IRQT_IPI:
-			per_cpu(ipi_to_irq, cpu_from_evtchn(evtchn))
-				[ipi_from_irq(irq)] = -1;
-			break;
-		default:
-			break;
-		}
-
-		/* Closed ports are implicitly re-bound to VCPU0. */
-		bind_evtchn_to_cpu(evtchn, 0);
-
-		evtchn_to_irq[evtchn] = -1;
-	}
-
-	BUG_ON(info_for_irq(irq)->type == IRQT_UNBOUND);
-
-	xen_free_irq(irq);
-
- done:
+	__unbind_from_irq(irq);
 	mutex_unlock(&irq_mapping_update_lock);
 }
 
@@ -1142,7 +1168,7 @@ void rebind_evtchn_irq(int evtchn, int irq)
 	   so there should be a proper type */
 	BUG_ON(info->type == IRQT_UNBOUND);
 
-	xen_irq_info_evtchn_init(irq, evtchn);
+	(void)xen_irq_info_evtchn_setup(irq, evtchn);
 
 	mutex_unlock(&irq_mapping_update_lock);
 
@@ -1317,7 +1343,7 @@ static void restore_cpu_virqs(unsigned int cpu)
 		evtchn = bind_virq.port;
 
 		/* Record the new mapping. */
-		xen_irq_info_virq_init(cpu, irq, evtchn, virq);
+		(void)xen_irq_info_virq_setup(cpu, irq, evtchn, virq);
 		bind_evtchn_to_cpu(evtchn, cpu);
 	}
 }
@@ -1341,7 +1367,7 @@ static void restore_cpu_ipis(unsigned int cpu)
 		evtchn = bind_ipi.port;
 
 		/* Record the new mapping. */
-		xen_irq_info_ipi_init(cpu, irq, evtchn, ipi);
+		(void)xen_irq_info_ipi_setup(cpu, irq, evtchn, ipi);
 		bind_evtchn_to_cpu(evtchn, cpu);
 	}
 }
-- 
1.7.2.5

From: David Vrabel <david.vrabel@citrix.com>

Add a hook for port-specific setup and call it from
xen_irq_info_common_setup().

The FIFO-based ABIs may need to perform additional setup (expanding
the event array) before a bound event channel can start to receive
events.

Signed-off-by: David Vrabel <david.vrabel@citrix.com>
---
 drivers/xen/events/events_base.c     |    2 +-
 drivers/xen/events/events_internal.h |   12 ++++++++++++
 2 files changed, 13 insertions(+), 1 deletions(-)

diff --git a/drivers/xen/events/events_base.c b/drivers/xen/events/events_base.c
index 4f7d94a..929eccb 100644
--- a/drivers/xen/events/events_base.c
+++ b/drivers/xen/events/events_base.c
@@ -117,7 +117,7 @@ static int xen_irq_info_common_setup(struct irq_info *info,
 
 	irq_clear_status_flags(irq, IRQ_NOREQUEST|IRQ_NOAUTOEN);
 
-	return 0;
+	return xen_evtchn_port_setup(info);
 }
 
 static int xen_irq_info_evtchn_setup(unsigned irq,
diff --git a/drivers/xen/events/events_internal.h
b/drivers/xen/events/events_internal.h
index ba8142f..dc96502 100644
--- a/drivers/xen/events/events_internal.h
+++ b/drivers/xen/events/events_internal.h
@@ -55,6 +55,7 @@ struct irq_info {
 #define PIRQ_SHAREABLE	(1 << 1)
 
 struct evtchn_ops {
+	int (*setup)(struct irq_info *info);
 	void (*bind_to_cpu)(struct irq_info *info, unsigned cpu);
 
 	void (*clear_pending)(unsigned port);
@@ -75,6 +76,17 @@ struct irq_info *info_for_irq(unsigned irq);
 unsigned cpu_from_irq(unsigned irq);
 unsigned cpu_from_evtchn(unsigned int evtchn);
 
+/*
+ * Do any ABI specific setup for a bound event channel before it can
+ * be unmasked and used.
+ */
+static inline int xen_evtchn_port_setup(struct irq_info *info)
+{
+	if (evtchn_ops->setup)
+		return evtchn_ops->setup(info);
+	return 0;
+}
+
 static inline void xen_evtchn_port_bind_to_cpu(struct irq_info *info,
 					       unsigned cpu)
 {
-- 
1.7.2.5

From: David Vrabel <david.vrabel@citrix.com>

Refactor static array evtchn_to_irq array to be dynamically allocated by
implementing get and set functions for accesses to the array.

Two new port ops are added: max_channels (maximum supported number of
event channels) and nr_channels (number of currently usable event
channels).  For the 2-level ABI, these numbers are both the same as
the shared data structure is a fixed size. For the FIFO ABI, these
will be different as the event array is expanded dynamically.

This allows more than 65000 event channels so an unsigned short is no
longer sufficient for an event channel port number and unsigned int is
used instead.

Signed-off-by: Malcolm Crossley <malcolm.crossley@citrix.com>
Signed-off-by: David Vrabel <david.vrabel@citrix.com>
---
 drivers/xen/events/events_2l.c       |   11 ++-
 drivers/xen/events/events_base.c     |  175 ++++++++++++++++++++++++----------
 drivers/xen/events/events_internal.h |   18 +++-
 3 files changed, 149 insertions(+), 55 deletions(-)

diff --git a/drivers/xen/events/events_2l.c b/drivers/xen/events/events_2l.c
index e55677c..ecb402a 100644
--- a/drivers/xen/events/events_2l.c
+++ b/drivers/xen/events/events_2l.c
@@ -41,6 +41,11 @@
 static DEFINE_PER_CPU(xen_ulong_t [NR_EVENT_CHANNELS/BITS_PER_EVTCHN_WORD],
 		      cpu_evtchn_mask);
 
+static unsigned evtchn_2l_max_channels(void)
+{
+	return NR_EVENT_CHANNELS;
+}
+
 static void evtchn_2l_bind_to_cpu(struct irq_info *info, unsigned cpu)
 {
 	clear_bit(info->evtchn, BM(per_cpu(cpu_evtchn_mask, info->cpu)));
@@ -238,7 +243,7 @@ static void evtchn_2l_handle_events(unsigned cpu)
 
 			/* Process port. */
 			port = (word_idx * BITS_PER_EVTCHN_WORD) + bit_idx;
-			irq = evtchn_to_irq[port];
+			irq = get_evtchn_to_irq(port);
 
 			if (irq != -1) {
 				desc = irq_to_desc(irq);
@@ -332,7 +337,7 @@ irqreturn_t xen_debug_interrupt(int irq, void *dev_id)
 			int word_idx = i / BITS_PER_EVTCHN_WORD;
 			printk("  %d: event %d -> irq %d%s%s%s\n",
 			       cpu_from_evtchn(i), i,
-			       evtchn_to_irq[i],
+			       get_evtchn_to_irq(i),
 			       sync_test_bit(word_idx, BM(&v->evtchn_pending_sel))
 			       ? "" : " l2-clear",
 			       !sync_test_bit(i, BM(sh->evtchn_mask))
@@ -348,6 +353,8 @@ irqreturn_t xen_debug_interrupt(int irq, void *dev_id)
 }
 
 static const struct evtchn_ops evtchn_ops_2l = {
+	.max_channels      = evtchn_2l_max_channels,
+	.nr_channels       = evtchn_2l_max_channels,
 	.bind_to_cpu       = evtchn_2l_bind_to_cpu,
 	.clear_pending     = evtchn_2l_clear_pending,
 	.set_pending       = evtchn_2l_set_pending,
diff --git a/drivers/xen/events/events_base.c b/drivers/xen/events/events_base.c
index 929eccb..a690666 100644
--- a/drivers/xen/events/events_base.c
+++ b/drivers/xen/events/events_base.c
@@ -77,12 +77,16 @@ static DEFINE_PER_CPU(int [NR_VIRQS], virq_to_irq) = {[0 ...
NR_VIRQS-1] = -1};
 /* IRQ <-> IPI mapping */
 static DEFINE_PER_CPU(int [XEN_NR_IPIS], ipi_to_irq) = {[0 ... XEN_NR_IPIS-1] =
-1};
 
-int *evtchn_to_irq;
+int **evtchn_to_irq;
 #ifdef CONFIG_X86
 static unsigned long *pirq_eoi_map;
 #endif
 static bool (*pirq_needs_eoi)(unsigned irq);
 
+#define EVTCHN_ROW(e)  (e / (PAGE_SIZE/sizeof(**evtchn_to_irq)))
+#define EVTCHN_COL(e)  (e % (PAGE_SIZE/sizeof(**evtchn_to_irq)))
+#define EVTCHN_PER_ROW (PAGE_SIZE / sizeof(**evtchn_to_irq))
+
 /* Xen will never allocate port zero for any purpose. */
 #define VALID_EVTCHN(chn)	((chn) != 0)
 
@@ -92,6 +96,61 @@ static struct irq_chip xen_pirq_chip;
 static void enable_dynirq(struct irq_data *data);
 static void disable_dynirq(struct irq_data *data);
 
+static void clear_evtchn_to_irq_row(unsigned row)
+{
+	unsigned col;
+
+	for (col = 0; col < EVTCHN_PER_ROW; col++)
+		evtchn_to_irq[row][col] = -1;
+}
+
+static void clear_evtchn_to_irq_all(void)
+{
+	unsigned row;
+
+	for (row = 0; row < EVTCHN_ROW(xen_evtchn_max_channels()); row++) {
+		if (evtchn_to_irq[row] == NULL)
+			continue;
+		clear_evtchn_to_irq_row(row);
+	}
+}
+
+static int set_evtchn_to_irq(unsigned evtchn, unsigned irq)
+{
+	unsigned row;
+	unsigned col;
+
+	if (evtchn >= xen_evtchn_max_channels())
+		return -EINVAL;
+
+	row = EVTCHN_ROW(evtchn);
+	col = EVTCHN_COL(evtchn);
+
+	if (evtchn_to_irq[row] == NULL) {
+		/* Unallocated irq entries return -1 anyway */
+		if (irq == -1)
+			return 0;
+
+		evtchn_to_irq[row] = (int *)get_zeroed_page(GFP_KERNEL);
+		if (evtchn_to_irq[row] == NULL)
+			return -ENOMEM;
+
+		clear_evtchn_to_irq_row(row);
+	}
+
+	evtchn_to_irq[EVTCHN_ROW(evtchn)][EVTCHN_COL(evtchn)] = irq;
+	return 0;
+}
+
+int get_evtchn_to_irq(unsigned evtchn)
+{
+	if (evtchn >= xen_evtchn_max_channels())
+		return -1;
+	if (evtchn_to_irq[EVTCHN_ROW(evtchn)] == NULL)
+		return -1;
+	return evtchn_to_irq[EVTCHN_ROW(evtchn)][EVTCHN_COL(evtchn)];
+}
+
 /* Get info for IRQ */
 struct irq_info *info_for_irq(unsigned irq)
 {
@@ -102,9 +161,10 @@ struct irq_info *info_for_irq(unsigned irq)
 static int xen_irq_info_common_setup(struct irq_info *info,
 				     unsigned irq,
 				     enum xen_irq_type type,
-				     unsigned short evtchn,
+				     unsigned evtchn,
 				     unsigned short cpu)
 {
+	int ret;
 
 	BUG_ON(info->type != IRQT_UNBOUND && info->type != type);
 
@@ -113,7 +173,9 @@ static int xen_irq_info_common_setup(struct irq_info *info,
 	info->evtchn = evtchn;
 	info->cpu = cpu;
 
-	evtchn_to_irq[evtchn] = irq;
+	ret = set_evtchn_to_irq(evtchn, irq);
+	if (ret < 0)
+		return ret;
 
 	irq_clear_status_flags(irq, IRQ_NOREQUEST|IRQ_NOAUTOEN);
 
@@ -121,7 +183,7 @@ static int xen_irq_info_common_setup(struct irq_info *info,
 }
 
 static int xen_irq_info_evtchn_setup(unsigned irq,
-				     unsigned short evtchn)
+				     unsigned evtchn)
 {
 	struct irq_info *info = info_for_irq(irq);
 
@@ -130,7 +192,7 @@ static int xen_irq_info_evtchn_setup(unsigned irq,
 
 static int xen_irq_info_ipi_setup(unsigned cpu,
 				  unsigned irq,
-				  unsigned short evtchn,
+				  unsigned evtchn,
 				  enum ipi_vector ipi)
 {
 	struct irq_info *info = info_for_irq(irq);
@@ -144,8 +206,8 @@ static int xen_irq_info_ipi_setup(unsigned cpu,
 
 static int xen_irq_info_virq_setup(unsigned cpu,
 				   unsigned irq,
-				   unsigned short evtchn,
-				   unsigned short virq)
+				   unsigned evtchn,
+				   unsigned virq)
 {
 	struct irq_info *info = info_for_irq(irq);
 
@@ -157,9 +219,9 @@ static int xen_irq_info_virq_setup(unsigned cpu,
 }
 
 static int xen_irq_info_pirq_setup(unsigned irq,
-				   unsigned short evtchn,
-				   unsigned short pirq,
-				   unsigned short gsi,
+				   unsigned evtchn,
+				   unsigned pirq,
+				   unsigned gsi,
 				   uint16_t domid,
 				   unsigned char flags)
 {
@@ -173,6 +235,12 @@ static int xen_irq_info_pirq_setup(unsigned irq,
 	return xen_irq_info_common_setup(info, irq, IRQT_PIRQ, evtchn, 0);
 }
 
+static void xen_irq_info_cleanup(struct irq_info *info)
+{
+	set_evtchn_to_irq(info->evtchn, -1);
+	info->evtchn = 0;
+}
+
 /*
  * Accessors for packed IRQ information.
  */
@@ -186,7 +254,7 @@ unsigned int evtchn_from_irq(unsigned irq)
 
 unsigned irq_from_evtchn(unsigned int evtchn)
 {
-	return evtchn_to_irq[evtchn];
+	return get_evtchn_to_irq(evtchn);
 }
 EXPORT_SYMBOL_GPL(irq_from_evtchn);
 
@@ -237,7 +305,7 @@ unsigned cpu_from_irq(unsigned irq)
 
 unsigned int cpu_from_evtchn(unsigned int evtchn)
 {
-	int irq = evtchn_to_irq[evtchn];
+	int irq = get_evtchn_to_irq(evtchn);
 	unsigned ret = 0;
 
 	if (irq != -1)
@@ -263,7 +331,7 @@ static bool pirq_needs_eoi_flag(unsigned irq)
 
 static void bind_evtchn_to_cpu(unsigned int chn, unsigned int cpu)
 {
-	int irq = evtchn_to_irq[chn];
+	int irq = get_evtchn_to_irq(chn);
 	struct irq_info *info = info_for_irq(irq);
 
 	BUG_ON(irq == -1);
@@ -386,6 +454,18 @@ static void xen_free_irq(unsigned irq)
 	irq_free_desc(irq);
 }
 
+static void xen_evtchn_close(unsigned int port)
+{
+	struct evtchn_close close;
+
+	close.port = port;
+	if (HYPERVISOR_event_channel_op(EVTCHNOP_close, &close) != 0)
+		BUG();
+
+	/* Closed ports are implicitly re-bound to VCPU0. */
+	bind_evtchn_to_cpu(port, 0);
+}
+
 static void pirq_query_unmask(int irq)
 {
 	struct physdev_irq_status_query irq_status;
@@ -458,7 +538,13 @@ static unsigned int __startup_pirq(unsigned int irq)
 
 	pirq_query_unmask(irq);
 
-	evtchn_to_irq[evtchn] = irq;
+	rc = set_evtchn_to_irq(evtchn, irq);
+	if (rc != 0) {
+		pr_err("irq%d: Failed to set port to irq mapping (%d)\n",
+		       irq, rc);
+		xen_evtchn_close(evtchn);
+		return 0;
+	}
 	bind_evtchn_to_cpu(evtchn, 0);
 	info->evtchn = evtchn;
 
@@ -476,10 +562,9 @@ static unsigned int startup_pirq(struct irq_data *data)
 
 static void shutdown_pirq(struct irq_data *data)
 {
-	struct evtchn_close close;
 	unsigned int irq = data->irq;
 	struct irq_info *info = info_for_irq(irq);
-	int evtchn = evtchn_from_irq(irq);
+	unsigned evtchn = evtchn_from_irq(irq);
 
 	BUG_ON(info->type != IRQT_PIRQ);
 
@@ -487,14 +572,8 @@ static void shutdown_pirq(struct irq_data *data)
 		return;
 
 	mask_evtchn(evtchn);
-
-	close.port = evtchn;
-	if (HYPERVISOR_event_channel_op(EVTCHNOP_close, &close) != 0)
-		BUG();
-
-	bind_evtchn_to_cpu(evtchn, 0);
-	evtchn_to_irq[evtchn] = -1;
-	info->evtchn = 0;
+	xen_evtchn_close(evtchn);
+	xen_irq_info_cleanup(info);
 }
 
 static void enable_pirq(struct irq_data *data)
@@ -525,7 +604,6 @@ EXPORT_SYMBOL_GPL(xen_irq_from_gsi);
 
 static void __unbind_from_irq(unsigned int irq)
 {
-	struct evtchn_close close;
 	int evtchn = evtchn_from_irq(irq);
 	struct irq_info *info = irq_get_handler_data(irq);
 
@@ -536,27 +614,22 @@ static void __unbind_from_irq(unsigned int irq)
 	}
 
 	if (VALID_EVTCHN(evtchn)) {
-		close.port = evtchn;
-		if (HYPERVISOR_event_channel_op(EVTCHNOP_close, &close) != 0)
-			BUG();
+		unsigned int cpu = cpu_from_irq(irq);
+
+		xen_evtchn_close(evtchn);
 
 		switch (type_from_irq(irq)) {
 		case IRQT_VIRQ:
-			per_cpu(virq_to_irq, cpu_from_evtchn(evtchn))
-				[virq_from_irq(irq)] = -1;
+			per_cpu(virq_to_irq, cpu)[virq_from_irq(irq)] = -1;
 			break;
 		case IRQT_IPI:
-			per_cpu(ipi_to_irq, cpu_from_evtchn(evtchn))
-				[ipi_from_irq(irq)] = -1;
+			per_cpu(ipi_to_irq, cpu)[ipi_from_irq(irq)] = -1;
 			break;
 		default:
 			break;
 		}
 
-		/* Closed ports are implicitly re-bound to VCPU0. */
-		bind_evtchn_to_cpu(evtchn, 0);
-
-		evtchn_to_irq[evtchn] = -1;
+		xen_irq_info_cleanup(info);
 	}
 
 	BUG_ON(info_for_irq(irq)->type == IRQT_UNBOUND);
@@ -760,9 +833,12 @@ int bind_evtchn_to_irq(unsigned int evtchn)
 	int irq;
 	int ret;
 
+	if (evtchn >= xen_evtchn_max_channels())
+		return -ENOMEM;
+
 	mutex_lock(&irq_mapping_update_lock);
 
-	irq = evtchn_to_irq[evtchn];
+	irq = get_evtchn_to_irq(evtchn);
 
 	if (irq == -1) {
 		irq = xen_allocate_irq_dynamic();
@@ -852,7 +928,7 @@ static int find_virq(unsigned int virq, unsigned int cpu)
 	int port, rc = -ENOENT;
 
 	memset(&status, 0, sizeof(status));
-	for (port = 0; port <= NR_EVENT_CHANNELS; port++) {
+	for (port = 0; port < xen_evtchn_max_channels(); port++) {
 		status.dom = DOMID_SELF;
 		status.port = port;
 		rc = HYPERVISOR_event_channel_op(EVTCHNOP_status, &status);
@@ -1022,7 +1098,7 @@ EXPORT_SYMBOL_GPL(unbind_from_irqhandler);
 
 int evtchn_make_refcounted(unsigned int evtchn)
 {
-	int irq = evtchn_to_irq[evtchn];
+	int irq = get_evtchn_to_irq(evtchn);
 	struct irq_info *info;
 
 	if (irq == -1)
@@ -1047,12 +1123,12 @@ int evtchn_get(unsigned int evtchn)
 	struct irq_info *info;
 	int err = -ENOENT;
 
-	if (evtchn >= NR_EVENT_CHANNELS)
+	if (evtchn >= xen_evtchn_max_channels())
 		return -EINVAL;
 
 	mutex_lock(&irq_mapping_update_lock);
 
-	irq = evtchn_to_irq[evtchn];
+	irq = get_evtchn_to_irq(evtchn);
 	if (irq == -1)
 		goto done;
 
@@ -1076,7 +1152,7 @@ EXPORT_SYMBOL_GPL(evtchn_get);
 
 void evtchn_put(unsigned int evtchn)
 {
-	int irq = evtchn_to_irq[evtchn];
+	int irq = get_evtchn_to_irq(evtchn);
 	if (WARN_ON(irq == -1))
 		return;
 	unbind_from_irq(irq);
@@ -1163,7 +1239,7 @@ void rebind_evtchn_irq(int evtchn, int irq)
 	mutex_lock(&irq_mapping_update_lock);
 
 	/* After resume the irq<->evtchn mappings are all cleared out */
-	BUG_ON(evtchn_to_irq[evtchn] != -1);
+	BUG_ON(get_evtchn_to_irq(evtchn) != -1);
 	/* Expect irq to have been bound before,
 	   so there should be a proper type */
 	BUG_ON(info->type == IRQT_UNBOUND);
@@ -1448,15 +1524,14 @@ void xen_irq_resume(void)
 	struct irq_info *info;
 
 	/* New event-channel space is not ''live'' yet. */
-	for (evtchn = 0; evtchn < NR_EVENT_CHANNELS; evtchn++)
+	for (evtchn = 0; evtchn < xen_evtchn_nr_channels(); evtchn++)
 		mask_evtchn(evtchn);
 
 	/* No IRQ <-> event-channel mappings. */
 	list_for_each_entry(info, &xen_irq_list_head, list)
 		info->evtchn = 0; /* zap event-channel binding */
 
-	for (evtchn = 0; evtchn < NR_EVENT_CHANNELS; evtchn++)
-		evtchn_to_irq[evtchn] = -1;
+	clear_evtchn_to_irq_all();
 
 	for_each_possible_cpu(cpu) {
 		restore_cpu_virqs(cpu);
@@ -1553,14 +1628,12 @@ void __init xen_init_IRQ(void)
 
 	xen_evtchn_2l_init();
 
-	evtchn_to_irq = kcalloc(NR_EVENT_CHANNELS, sizeof(*evtchn_to_irq),
-				    GFP_KERNEL);
+	evtchn_to_irq = kcalloc(EVTCHN_ROW(xen_evtchn_max_channels()),
+				sizeof(*evtchn_to_irq), GFP_KERNEL);
 	BUG_ON(!evtchn_to_irq);
-	for (i = 0; i < NR_EVENT_CHANNELS; i++)
-		evtchn_to_irq[i] = -1;
 
 	/* No event channels are ''live'' right now. */
-	for (i = 0; i < NR_EVENT_CHANNELS; i++)
+	for (i = 0; i < xen_evtchn_nr_channels(); i++)
 		mask_evtchn(i);
 
 	pirq_needs_eoi = pirq_needs_eoi_flag;
diff --git a/drivers/xen/events/events_internal.h
b/drivers/xen/events/events_internal.h
index dc96502..a3d9aec 100644
--- a/drivers/xen/events/events_internal.h
+++ b/drivers/xen/events/events_internal.h
@@ -35,7 +35,7 @@ struct irq_info {
 	int refcnt;
 	enum xen_irq_type type;	/* type */
 	unsigned irq;
-	unsigned short evtchn;	/* event channel */
+	unsigned int evtchn;	/* event channel */
 	unsigned short cpu;	/* cpu bound */
 
 	union {
@@ -55,6 +55,9 @@ struct irq_info {
 #define PIRQ_SHAREABLE	(1 << 1)
 
 struct evtchn_ops {
+	unsigned (*max_channels)(void);
+	unsigned (*nr_channels)(void);
+
 	int (*setup)(struct irq_info *info);
 	void (*bind_to_cpu)(struct irq_info *info, unsigned cpu);
 
@@ -70,12 +73,23 @@ struct evtchn_ops {
 
 extern const struct evtchn_ops *evtchn_ops;
 
-extern int *evtchn_to_irq;
+extern int **evtchn_to_irq;
+int get_evtchn_to_irq(unsigned int evtchn);
 
 struct irq_info *info_for_irq(unsigned irq);
 unsigned cpu_from_irq(unsigned irq);
 unsigned cpu_from_evtchn(unsigned int evtchn);
 
+static inline unsigned xen_evtchn_max_channels(void)
+{
+	return evtchn_ops->max_channels();
+}
+
+static inline unsigned xen_evtchn_nr_channels(void)
+{
+	return evtchn_ops->nr_channels();
+}
+
 /*
  * Do any ABI specific setup for a bound event channel before it can
  * be unmasked and used.
-- 
1.7.2.5

From: David Vrabel <david.vrabel@citrix.com>

Signed-off-by: David Vrabel <david.vrabel@citrix.com>
Reviewed-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
---
 drivers/xen/events/events_base.c |   18 +++++++++++-------
 1 files changed, 11 insertions(+), 7 deletions(-)

diff --git a/drivers/xen/events/events_base.c b/drivers/xen/events/events_base.c
index a690666..c6d64f1 100644
--- a/drivers/xen/events/events_base.c
+++ b/drivers/xen/events/events_base.c
@@ -344,6 +344,14 @@ static void bind_evtchn_to_cpu(unsigned int chn, unsigned
int cpu)
 	info->cpu = cpu;
 }
 
+static void xen_evtchn_mask_all(void)
+{
+	unsigned int evtchn;
+
+	for (evtchn = 0; evtchn < xen_evtchn_nr_channels(); evtchn++)
+		mask_evtchn(evtchn);
+}
+
 /**
  * notify_remote_via_irq - send event to remote end of event channel via irq
  * @irq: irq of event channel to send event to
@@ -1520,12 +1528,11 @@ EXPORT_SYMBOL_GPL(xen_test_irq_shared);
 
 void xen_irq_resume(void)
 {
-	unsigned int cpu, evtchn;
+	unsigned int cpu;
 	struct irq_info *info;
 
 	/* New event-channel space is not ''live'' yet. */
-	for (evtchn = 0; evtchn < xen_evtchn_nr_channels(); evtchn++)
-		mask_evtchn(evtchn);
+	xen_evtchn_mask_all();
 
 	/* No IRQ <-> event-channel mappings. */
 	list_for_each_entry(info, &xen_irq_list_head, list)
@@ -1624,8 +1631,6 @@ void xen_callback_vector(void) {}
 
 void __init xen_init_IRQ(void)
 {
-	int i;
-
 	xen_evtchn_2l_init();
 
 	evtchn_to_irq = kcalloc(EVTCHN_ROW(xen_evtchn_max_channels()),
@@ -1633,8 +1638,7 @@ void __init xen_init_IRQ(void)
 	BUG_ON(!evtchn_to_irq);
 
 	/* No event channels are ''live'' right now. */
-	for (i = 0; i < xen_evtchn_nr_channels(); i++)
-		mask_evtchn(i);
+	xen_evtchn_mask_all();
 
 	pirq_needs_eoi = pirq_needs_eoi_flag;
 
-- 
1.7.2.5

From: David Vrabel <david.vrabel@citrix.com>

Remove the check during unbind for NR_EVENT_CHANNELS as this limits
support to less than 4096 ports.

Signed-off-by: David Vrabel <david.vrabel@citrix.com>
---
 drivers/xen/events/events_base.c     |   13 +++++++++++++
 drivers/xen/events/events_internal.h |    5 -----
 drivers/xen/evtchn.c                 |    2 +-
 include/xen/events.h                 |    2 ++
 4 files changed, 16 insertions(+), 6 deletions(-)

diff --git a/drivers/xen/events/events_base.c b/drivers/xen/events/events_base.c
index c6d64f1..9d0d88c 100644
--- a/drivers/xen/events/events_base.c
+++ b/drivers/xen/events/events_base.c
@@ -952,6 +952,19 @@ static int find_virq(unsigned int virq, unsigned int cpu)
 	return rc;
 }
 
+/**
+ * xen_evtchn_nr_channels - number of usable event channel ports
+ *
+ * This may be less than the maximum supported by the current
+ * hypervisor ABI. Use xen_evtchn_max_channels() for the maximum
+ * supported.
+ */
+unsigned xen_evtchn_nr_channels(void)
+{
+        return evtchn_ops->nr_channels();
+}
+EXPORT_SYMBOL_GPL(xen_evtchn_nr_channels);
+
 int bind_virq_to_irq(unsigned int virq, unsigned int cpu)
 {
 	struct evtchn_bind_virq bind_virq;
diff --git a/drivers/xen/events/events_internal.h
b/drivers/xen/events/events_internal.h
index a3d9aec..2862e1c 100644
--- a/drivers/xen/events/events_internal.h
+++ b/drivers/xen/events/events_internal.h
@@ -85,11 +85,6 @@ static inline unsigned xen_evtchn_max_channels(void)
 	return evtchn_ops->max_channels();
 }
 
-static inline unsigned xen_evtchn_nr_channels(void)
-{
-	return evtchn_ops->nr_channels();
-}
-
 /*
  * Do any ABI specific setup for a bound event channel before it can
  * be unmasked and used.
diff --git a/drivers/xen/evtchn.c b/drivers/xen/evtchn.c
index 8b3a69a..0b53c0b 100644
--- a/drivers/xen/evtchn.c
+++ b/drivers/xen/evtchn.c
@@ -417,7 +417,7 @@ static long evtchn_ioctl(struct file *file,
 			break;
 
 		rc = -EINVAL;
-		if (unbind.port >= NR_EVENT_CHANNELS)
+		if (unbind.port >= xen_evtchn_nr_channels())
 			break;
 
 		rc = -ENOTCONN;
diff --git a/include/xen/events.h b/include/xen/events.h
index 32ae0f2..55b42cc 100644
--- a/include/xen/events.h
+++ b/include/xen/events.h
@@ -7,6 +7,8 @@
 #include <asm/xen/hypercall.h>
 #include <asm/xen/events.h>
 
+unsigned xen_evtchn_nr_channels(void);
+
 int bind_evtchn_to_irq(unsigned int evtchn);
 int bind_evtchn_to_irqhandler(unsigned int evtchn,
 			      irq_handler_t handler,
-- 
1.7.2.5

From: David Vrabel <david.vrabel@citrix.com>

Add the hypercall sub-ops and the structures for the shared data used
in the FIFO-based event channel ABI.

The design document for this new ABI is available here:

    http://xenbits.xen.org/people/dvrabel/event-channels-F.pdf

In summary, events are reported using a per-domain shared event array
of event words.  Each event word has PENDING, LINKED and MASKED bits
and a LINK field for pointing to the next event in the event queue.

There are 16 event queues (with different priorities) per-VCPU.

Key advantages of this new ABI include:

- Support for over 100,000 events (2^17).
- 16 different event priorities.
- Improved fairness in event latency through the use of FIFOs.

The ABI is available in Xen 4.4 and later.

Signed-off-by: David Vrabel <david.vrabel@citrix.com>
---
 drivers/xen/events/events_2l.c        |    8 ++--
 include/xen/interface/event_channel.h |   67 +++++++++++++++++++++++++++++++++
 include/xen/interface/xen.h           |    6 ---
 3 files changed, 71 insertions(+), 10 deletions(-)

diff --git a/drivers/xen/events/events_2l.c b/drivers/xen/events/events_2l.c
index ecb402a..d7ff917 100644
--- a/drivers/xen/events/events_2l.c
+++ b/drivers/xen/events/events_2l.c
@@ -38,12 +38,12 @@
 /* Find the first set bit in a evtchn mask */
 #define EVTCHN_FIRST_BIT(w) find_first_bit(BM(&(w)), BITS_PER_EVTCHN_WORD)
 
-static DEFINE_PER_CPU(xen_ulong_t [NR_EVENT_CHANNELS/BITS_PER_EVTCHN_WORD],
+static DEFINE_PER_CPU(xen_ulong_t [EVTCHN_2L_NR_CHANNELS/BITS_PER_EVTCHN_WORD],
 		      cpu_evtchn_mask);
 
 static unsigned evtchn_2l_max_channels(void)
 {
-	return NR_EVENT_CHANNELS;
+	return EVTCHN_2L_NR_CHANNELS;
 }
 
 static void evtchn_2l_bind_to_cpu(struct irq_info *info, unsigned cpu)
@@ -316,7 +316,7 @@ irqreturn_t xen_debug_interrupt(int irq, void *dev_id)
 		       i % 8 == 0 ? "\n   " : " ");
 
 	printk("\nlocal cpu%d mask:\n   ", cpu);
-	for (i = (NR_EVENT_CHANNELS/BITS_PER_EVTCHN_WORD)-1; i >= 0; i--)
+	for (i = (EVTCHN_2L_NR_CHANNELS/BITS_PER_EVTCHN_WORD)-1; i >= 0; i--)
 		printk("%0*"PRI_xen_ulong"%s",
(int)(sizeof(cpu_evtchn[0])*2),
 		       cpu_evtchn[i],
 		       i % 8 == 0 ? "\n   " : " ");
@@ -332,7 +332,7 @@ irqreturn_t xen_debug_interrupt(int irq, void *dev_id)
 	}
 
 	printk("\npending list:\n");
-	for (i = 0; i < NR_EVENT_CHANNELS; i++) {
+	for (i = 0; i < EVTCHN_2L_NR_CHANNELS; i++) {
 		if (sync_test_bit(i, BM(sh->evtchn_pending))) {
 			int word_idx = i / BITS_PER_EVTCHN_WORD;
 			printk("  %d: event %d -> irq %d%s%s%s\n",
diff --git a/include/xen/interface/event_channel.h
b/include/xen/interface/event_channel.h
index f494292..0cd1e73 100644
--- a/include/xen/interface/event_channel.h
+++ b/include/xen/interface/event_channel.h
@@ -190,6 +190,39 @@ struct evtchn_reset {
 };
 typedef struct evtchn_reset evtchn_reset_t;
 
+/*
+ * EVTCHNOP_init_control: initialize the control block for the FIFO ABI.
+ */
+#define EVTCHNOP_init_control    11
+struct evtchn_init_control {
+	/* IN parameters. */
+	uint64_t control_gfn;
+	uint32_t offset;
+	uint32_t vcpu;
+	/* OUT parameters. */
+	uint8_t link_bits;
+	uint8_t _pad[7];
+};
+
+/*
+ * EVTCHNOP_expand_array: add an additional page to the event array.
+ */
+#define EVTCHNOP_expand_array    12
+struct evtchn_expand_array {
+	/* IN parameters. */
+	uint64_t array_gfn;
+};
+
+/*
+ * EVTCHNOP_set_priority: set the priority for an event channel.
+ */
+#define EVTCHNOP_set_priority    13
+struct evtchn_set_priority {
+	/* IN parameters. */
+	uint32_t port;
+	uint32_t priority;
+};
+
 struct evtchn_op {
 	uint32_t cmd; /* EVTCHNOP_* */
 	union {
@@ -207,4 +240,38 @@ struct evtchn_op {
 };
 DEFINE_GUEST_HANDLE_STRUCT(evtchn_op);
 
+/*
+ * 2-level ABI
+ */
+
+#define EVTCHN_2L_NR_CHANNELS (sizeof(xen_ulong_t) * sizeof(xen_ulong_t) * 64)
+
+/*
+ * FIFO ABI
+ */
+
+/* Events may have priorities from 0 (highest) to 15 (lowest). */
+#define EVTCHN_FIFO_PRIORITY_MAX     0
+#define EVTCHN_FIFO_PRIORITY_DEFAULT 7
+#define EVTCHN_FIFO_PRIORITY_MIN     15
+
+#define EVTCHN_FIFO_MAX_QUEUES (EVTCHN_FIFO_PRIORITY_MIN + 1)
+
+typedef uint32_t event_word_t;
+
+#define EVTCHN_FIFO_PENDING 31
+#define EVTCHN_FIFO_MASKED  30
+#define EVTCHN_FIFO_LINKED  29
+
+#define EVTCHN_FIFO_LINK_BITS 17
+#define EVTCHN_FIFO_LINK_MASK ((1 << EVTCHN_FIFO_LINK_BITS) - 1)
+
+#define EVTCHN_FIFO_NR_CHANNELS (1 << EVTCHN_FIFO_LINK_BITS)
+
+struct evtchn_fifo_control_block {
+	uint32_t     ready;
+	uint32_t     _rsvd;
+	event_word_t head[EVTCHN_FIFO_MAX_QUEUES];
+};
+
 #endif /* __XEN_PUBLIC_EVENT_CHANNEL_H__ */
diff --git a/include/xen/interface/xen.h b/include/xen/interface/xen.h
index 53ec416..0cd5ca3 100644
--- a/include/xen/interface/xen.h
+++ b/include/xen/interface/xen.h
@@ -281,12 +281,6 @@ struct multicall_entry {
 };
 DEFINE_GUEST_HANDLE_STRUCT(multicall_entry);
 
-/*
- * Event channel endpoints per domain:
- *  1024 if a long is 32 bits; 4096 if a long is 64 bits.
- */
-#define NR_EVENT_CHANNELS (sizeof(xen_ulong_t) * sizeof(xen_ulong_t) * 64)
-
 struct vcpu_time_info {
 	/*
 	 * Updates to the following values are preceded and followed
-- 
1.7.2.5

From: David Vrabel <david.vrabel@citrix.com>

Add xen_irq_set_priority() to set an event channels priority.  This function
will only work with event channel ABIs that support priority (i.e., the
FIFO-based ABI).

Signed-off-by: David Vrabel <david.vrabel@citrix.com>
---
 drivers/xen/events/events_base.c |   17 +++++++++++++++++
 include/xen/events.h             |    5 +++++
 2 files changed, 22 insertions(+), 0 deletions(-)

diff --git a/drivers/xen/events/events_base.c b/drivers/xen/events/events_base.c
index 9d0d88c..e9001fe 100644
--- a/drivers/xen/events/events_base.c
+++ b/drivers/xen/events/events_base.c
@@ -1117,6 +1117,23 @@ void unbind_from_irqhandler(unsigned int irq, void
*dev_id)
 }
 EXPORT_SYMBOL_GPL(unbind_from_irqhandler);
 
+/**
+ * xen_set_irq_priority() - set an event channel priority.
+ * @irq:irq bound to an event channel.
+ * @priority: priority between XEN_IRQ_PRIORITY_MAX and XEN_IRQ_PRIORITY_MIN.
+ */
+int xen_set_irq_priority(unsigned irq, unsigned priority)
+{
+	struct evtchn_set_priority set_priority;
+
+	set_priority.port = evtchn_from_irq(irq);
+	set_priority.priority = priority;
+
+	return HYPERVISOR_event_channel_op(EVTCHNOP_set_priority,
+					   &set_priority);
+}
+EXPORT_SYMBOL_GPL(xen_set_irq_priority);
+
 int evtchn_make_refcounted(unsigned int evtchn)
 {
 	int irq = get_evtchn_to_irq(evtchn);
diff --git a/include/xen/events.h b/include/xen/events.h
index 55b42cc..c9c85cf 100644
--- a/include/xen/events.h
+++ b/include/xen/events.h
@@ -39,6 +39,11 @@ int bind_interdomain_evtchn_to_irqhandler(unsigned int
remote_domain,
  */
 void unbind_from_irqhandler(unsigned int irq, void *dev_id);
 
+#define XEN_IRQ_PRIORITY_MAX     EVTCHN_FIFO_PRIORITY_MAX
+#define XEN_IRQ_PRIORITY_DEFAULT EVTCHN_FIFO_PRIORITY_DEFAULT
+#define XEN_IRQ_PRIORITY_MIN     EVTCHN_FIFO_PRIORITY_MIN
+int xen_set_irq_priority(unsigned irq, unsigned priority);
+
 /*
  * Allow extra references to event channels exposed to userspace by evtchn
  */
-- 
1.7.2.5

From: David Vrabel <david.vrabel@citrix.com>

Commit bee980d9e (xen/events: Handle VIRQ_TIMER before any other hardirq
in event loop) effectively made the VIRQ_TIMER the highest priority event
when using the 2-level ABI.

Set the VIRQ_TIMER priority to the highest so this behaviour is retained
when using the FIFO-based ABI.

Signed-off-by: David Vrabel <david.vrabel@citrix.com>
---
 arch/x86/xen/time.c |    1 +
 1 files changed, 1 insertions(+), 0 deletions(-)

diff --git a/arch/x86/xen/time.c b/arch/x86/xen/time.c
index ee36589..10e11c1 100644
--- a/arch/x86/xen/time.c
+++ b/arch/x86/xen/time.c
@@ -447,6 +447,7 @@ void xen_setup_timer(int cpu)
 				      IRQF_NOBALANCING|IRQF_TIMER|
 				      IRQF_FORCE_RESUME,
 				      name, NULL);
+	(void)xen_set_irq_priority(irq, XEN_IRQ_PRIORITY_MAX);
 
 	memcpy(evt, xen_clockevent, sizeof(*evt));
 
-- 
1.7.2.5

From: David Vrabel <david.vrabel@citrix.com>

Implement all the event channel port ops for the FIFO-based ABI.

If the hypervisor supports the FIFO-based ABI, enable it by
initializing the control block for the boot VCPU and subsequent VCPUs
as they are brought up and on resume.  The event array is expanded as
required when event ports are setup.

The ''xen.fifo_events=0'' command line option may be used to
disable use
of the FIFO-based ABI.

Signed-off-by: David Vrabel <david.vrabel@citrix.com>
---
 drivers/xen/events/Makefile          |    1 +
 drivers/xen/events/events_base.c     |   14 +-
 drivers/xen/events/events_fifo.c     |  410 ++++++++++++++++++++++++++++++++++
 drivers/xen/events/events_internal.h |    8 +
 4 files changed, 432 insertions(+), 1 deletions(-)
 create mode 100644 drivers/xen/events/events_fifo.c

diff --git a/drivers/xen/events/Makefile b/drivers/xen/events/Makefile
index 08179fe..62be55c 100644
--- a/drivers/xen/events/Makefile
+++ b/drivers/xen/events/Makefile
@@ -2,3 +2,4 @@ obj-y += events.o
 
 events-y += events_base.o
 events-y += events_2l.o
+events-y += events_fifo.o
diff --git a/drivers/xen/events/events_base.c b/drivers/xen/events/events_base.c
index e9001fe..1d16185 100644
--- a/drivers/xen/events/events_base.c
+++ b/drivers/xen/events/events_base.c
@@ -1563,6 +1563,7 @@ void xen_irq_resume(void)
 
 	/* New event-channel space is not ''live'' yet. */
 	xen_evtchn_mask_all();
+	xen_evtchn_resume();
 
 	/* No IRQ <-> event-channel mappings. */
 	list_for_each_entry(info, &xen_irq_list_head, list)
@@ -1659,9 +1660,20 @@ void xen_callback_vector(void)
 void xen_callback_vector(void) {}
 #endif
 
+#undef MODULE_PARAM_PREFIX
+#define MODULE_PARAM_PREFIX "xen."
+
+static bool fifo_events = true;
+module_param(fifo_events, bool, 0);
+
 void __init xen_init_IRQ(void)
 {
-	xen_evtchn_2l_init();
+	int ret = -EINVAL;
+
+	if (fifo_events)
+		ret = xen_evtchn_fifo_init();
+	if (ret < 0)
+		xen_evtchn_2l_init();
 
 	evtchn_to_irq = kcalloc(EVTCHN_ROW(xen_evtchn_max_channels()),
 				sizeof(*evtchn_to_irq), GFP_KERNEL);
diff --git a/drivers/xen/events/events_fifo.c b/drivers/xen/events/events_fifo.c
new file mode 100644
index 0000000..cb47b43
--- /dev/null
+++ b/drivers/xen/events/events_fifo.c
@@ -0,0 +1,410 @@
+/*
+ * Xen event channels (FIFO-based ABI)
+ *
+ * Copyright (C) 2013 Citrix Systems R&D ltd.
+ *
+ * This source code is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License as
+ * published by the Free Software Foundation; either version 2 of the
+ * License, or (at your option) any later version.
+ *
+ * Or, when distributed separately from the Linux kernel or
+ * incorporated into other software packages, subject to the following
+ * license:
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this source file (the "Software"), to deal in the Software
without
+ * restriction, including without limitation the rights to use, copy, modify,
+ * merge, publish, distribute, sublicense, and/or sell copies of the Software,
+ * and to permit persons to whom the Software is furnished to do so, subject to
+ * the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
+ * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS
+ * IN THE SOFTWARE.
+ */
+
+#define pr_fmt(fmt) "xen:" KBUILD_MODNAME ": " fmt
+
+#include <linux/linkage.h>
+#include <linux/interrupt.h>
+#include <linux/irq.h>
+#include <linux/module.h>
+#include <linux/smp.h>
+#include <linux/percpu.h>
+#include <linux/cpu.h>
+
+#include <asm/sync_bitops.h>
+#include <asm/xen/hypercall.h>
+#include <asm/xen/hypervisor.h>
+#include <asm/xen/page.h>
+
+#include <xen/xen.h>
+#include <xen/xen-ops.h>
+#include <xen/events.h>
+#include <xen/interface/xen.h>
+#include <xen/interface/event_channel.h>
+
+#include "events_internal.h"
+
+#define EVENT_WORDS_PER_PAGE (PAGE_SIZE / sizeof(event_word_t))
+#define MAX_EVENT_ARRAY_PAGES (EVTCHN_FIFO_NR_CHANNELS / EVENT_WORDS_PER_PAGE)
+
+struct evtchn_fifo_queue {
+	uint32_t head[EVTCHN_FIFO_MAX_QUEUES];
+};
+
+static DEFINE_PER_CPU(struct evtchn_fifo_control_block *, cpu_control_block);
+static DEFINE_PER_CPU(struct evtchn_fifo_queue, cpu_queue);
+static event_word_t *event_array[MAX_EVENT_ARRAY_PAGES] __read_mostly;
+static unsigned event_array_pages __read_mostly;
+
+#define BM(w) ((unsigned long *)(w))
+
+static inline event_word_t *event_word_from_port(unsigned port)
+{
+	unsigned i = port / EVENT_WORDS_PER_PAGE;
+
+	return event_array[i] + port % EVENT_WORDS_PER_PAGE;
+}
+
+static unsigned evtchn_fifo_max_channels(void)
+{
+	return EVTCHN_FIFO_NR_CHANNELS;
+}
+
+static unsigned evtchn_fifo_nr_channels(void)
+{
+	return event_array_pages * EVENT_WORDS_PER_PAGE;
+}
+
+static void free_unused_array_pages(void)
+{
+	unsigned i;
+
+	for (i = event_array_pages; i < MAX_EVENT_ARRAY_PAGES; i++) {
+		if (!event_array[i])
+			break;
+		free_page((unsigned long)event_array[i]);
+		event_array[i] = NULL;
+	}
+}
+
+static void init_array_page(event_word_t *array_page)
+{
+	unsigned i;
+
+	for (i = 0; i < EVENT_WORDS_PER_PAGE; i++)
+		array_page[i] = 1 << EVTCHN_FIFO_MASKED;
+}
+
+static int evtchn_fifo_setup(struct irq_info *info)
+{
+	unsigned port = info->evtchn;
+	unsigned new_array_pages;
+	int ret = -ENOMEM;
+
+	new_array_pages = port / EVENT_WORDS_PER_PAGE + 1;
+
+	if (new_array_pages > MAX_EVENT_ARRAY_PAGES)
+		return -EINVAL;
+
+	while (event_array_pages < new_array_pages) {
+		void *array_page;
+		struct evtchn_expand_array expand_array;
+
+		/* Might already have a page if we''ve resumed. */
+		array_page = event_array[event_array_pages];
+		if (!array_page) {
+			array_page = (void *)__get_free_page(GFP_KERNEL);
+			if (array_page == NULL)
+				goto error;
+			event_array[event_array_pages] = array_page;
+		}
+
+		/* Mask all events in this page before adding it. */
+		init_array_page(array_page);
+
+		expand_array.array_gfn = virt_to_mfn(array_page);
+
+		ret = HYPERVISOR_event_channel_op(EVTCHNOP_expand_array, &expand_array);
+		if (ret < 0)
+			goto error;
+
+		event_array_pages++;
+	}
+	return 0;
+
+  error:
+	if (event_array_pages == 0)
+		panic("xen: unable to expand event array with initial page (%d)\n",
ret);
+	else
+		pr_err("unable to expand event array (%d)\n", ret);
+	free_unused_array_pages();
+	return ret;
+}
+
+static void evtchn_fifo_bind_to_cpu(struct irq_info *info, unsigned cpu)
+{
+	/* no-op */
+}
+
+static void evtchn_fifo_clear_pending(unsigned port)
+{
+	event_word_t *word = event_word_from_port(port);
+	sync_clear_bit(EVTCHN_FIFO_PENDING, BM(word));
+}
+
+static void evtchn_fifo_set_pending(unsigned port)
+{
+	event_word_t *word = event_word_from_port(port);
+	sync_set_bit(EVTCHN_FIFO_PENDING, BM(word));
+}
+
+static bool evtchn_fifo_is_pending(unsigned port)
+{
+	event_word_t *word = event_word_from_port(port);
+	return sync_test_bit(EVTCHN_FIFO_PENDING, BM(word));
+}
+
+static bool evtchn_fifo_test_and_set_mask(unsigned port)
+{
+	event_word_t *word = event_word_from_port(port);
+	return sync_test_and_set_bit(EVTCHN_FIFO_MASKED, BM(word));
+}
+
+static void evtchn_fifo_mask(unsigned port)
+{
+	event_word_t *word = event_word_from_port(port);
+	sync_set_bit(EVTCHN_FIFO_MASKED, BM(word));
+}
+
+static void evtchn_fifo_unmask(unsigned port)
+{
+	event_word_t *word = event_word_from_port(port);
+
+	BUG_ON(!irqs_disabled());
+
+	sync_clear_bit(EVTCHN_FIFO_MASKED, BM(word));
+	if (sync_test_bit(EVTCHN_FIFO_PENDING, BM(word))) {
+		struct evtchn_unmask unmask = { .port = port };
+		(void)HYPERVISOR_event_channel_op(EVTCHNOP_unmask, &unmask);
+	}
+}
+
+static uint32_t clear_linked(volatile event_word_t *word)
+{
+	event_word_t new, old, w;
+
+	w = *word;
+
+	do {
+		old = w;
+		new = (w & ~((1 << EVTCHN_FIFO_LINKED)
+			     | EVTCHN_FIFO_LINK_MASK));
+	} while ((w = sync_cmpxchg(word, old, new)) != old);
+
+	return w & EVTCHN_FIFO_LINK_MASK;
+}
+
+static void handle_irq_for_port(unsigned port)
+{
+	int irq;
+	struct irq_desc *desc;
+
+	irq = get_evtchn_to_irq(port);
+	if (irq != -1) {
+		desc = irq_to_desc(irq);
+		if (desc)
+			generic_handle_irq_desc(irq, desc);
+	}
+}
+
+static void consume_one_event(unsigned cpu,
+			      struct evtchn_fifo_control_block *control_block,
+			      unsigned priority, uint32_t *ready)
+{
+	struct evtchn_fifo_queue *q = &per_cpu(cpu_queue, cpu);
+	uint32_t head;
+	unsigned port;
+	event_word_t *word;
+
+	head = q->head[priority];
+
+	/*
+	 * Reached the tail last time?  Read the new HEAD from the
+	 * control block.
+	 */
+	if (head == 0) {
+		rmb(); /* Ensure word is up-to-date before reading head. */
+		head = control_block->head[priority];
+	}
+
+	port = head;
+	word = event_word_from_port(port);
+	head = clear_linked(word);
+
+	/*
+	 * If the link is non-zero, there are more events in the
+	 * queue, otherwise the queue is empty.
+	 *
+	 * If the queue is empty, clear this priority from our local
+	 * copy of the ready word.
+	 */
+	if (head == 0)
+		clear_bit(priority, BM(ready));
+
+	if (sync_test_bit(EVTCHN_FIFO_PENDING, BM(word))
+	    && !sync_test_bit(EVTCHN_FIFO_MASKED, BM(word)))
+		handle_irq_for_port(port);
+
+	q->head[priority] = head;
+}
+
+static void evtchn_fifo_handle_events(unsigned cpu)
+{
+	struct evtchn_fifo_control_block *control_block;
+	uint32_t ready;
+	unsigned q;
+
+	control_block = per_cpu(cpu_control_block, cpu);
+
+	ready = xchg(&control_block->ready, 0);
+
+	while (ready) {
+		q = find_first_bit(BM(&ready), EVTCHN_FIFO_MAX_QUEUES);
+		consume_one_event(cpu, control_block, q, &ready);
+		ready |= xchg(&control_block->ready, 0);
+	}
+}
+
+static void evtchn_fifo_resume(void)
+{
+	unsigned cpu;
+
+	for_each_possible_cpu(cpu) {
+		void *control_block = per_cpu(cpu_control_block, cpu);
+		struct evtchn_init_control init_control;
+		int ret;
+
+		if (!control_block)
+			continue;
+
+		/*
+		 * If this CPU is offline, take the opportunity to
+		 * free the control block while it is not being
+		 * used.
+		 */
+		if (!cpu_online(cpu)) {
+			free_page((unsigned long)control_block);
+			per_cpu(cpu_control_block, cpu) = NULL;
+			continue;
+		}
+
+		init_control.control_gfn = virt_to_mfn(control_block);
+		init_control.offset = 0;
+		init_control.vcpu = cpu;
+
+		ret = HYPERVISOR_event_channel_op(EVTCHNOP_init_control,
+						  &init_control);
+		if (ret < 0)
+			BUG();
+	}
+
+	/*
+	 * The event array starts out as empty again and is extended
+	 * as normal when events are bound.  The existing pages will
+	 * be reused.
+	 */
+	event_array_pages = 0;
+}
+
+static const struct evtchn_ops evtchn_ops_fifo = {
+	.max_channels      = evtchn_fifo_max_channels,
+	.nr_channels       = evtchn_fifo_nr_channels,
+	.setup             = evtchn_fifo_setup,
+	.bind_to_cpu       = evtchn_fifo_bind_to_cpu,
+	.clear_pending     = evtchn_fifo_clear_pending,
+	.set_pending       = evtchn_fifo_set_pending,
+	.is_pending        = evtchn_fifo_is_pending,
+	.test_and_set_mask = evtchn_fifo_test_and_set_mask,
+	.mask              = evtchn_fifo_mask,
+	.unmask            = evtchn_fifo_unmask,
+	.handle_events     = evtchn_fifo_handle_events,
+	.resume            = evtchn_fifo_resume,
+};
+
+static int __cpuinit evtchn_fifo_init_control_block(unsigned cpu)
+{
+	struct page *control_block = NULL;
+	struct evtchn_init_control init_control;
+	int ret = -ENOMEM;
+
+	control_block = alloc_page(GFP_KERNEL|__GFP_ZERO);
+	if (control_block == NULL)
+		goto error;
+
+	init_control.control_gfn = virt_to_mfn(page_address(control_block));
+	init_control.offset      = 0;
+	init_control.vcpu        = cpu;
+
+	ret = HYPERVISOR_event_channel_op(EVTCHNOP_init_control, &init_control);
+	if (ret < 0)
+		goto error;
+
+	per_cpu(cpu_control_block, cpu) = page_address(control_block);
+
+	return 0;
+
+  error:
+	__free_page(control_block);
+	return ret;
+}
+
+static int __cpuinit evtchn_fifo_cpu_notification(struct notifier_block *self,
+						  unsigned long action,
+						  void *hcpu)
+{
+	int cpu = (long)hcpu;
+	int ret = 0;
+
+	switch (action) {
+	case CPU_UP_PREPARE:
+		if (!per_cpu(cpu_control_block, cpu))
+			ret = evtchn_fifo_init_control_block(cpu);
+		break;
+	default:
+		break;
+	}
+	return ret < 0 ? NOTIFY_BAD : NOTIFY_OK;
+}
+
+static struct notifier_block evtchn_fifo_cpu_notifier __cpuinitdata = {
+	.notifier_call	= evtchn_fifo_cpu_notification,
+};
+
+int __init xen_evtchn_fifo_init(void)
+{
+	int cpu = get_cpu();
+	int ret;
+
+	ret = evtchn_fifo_init_control_block(cpu);
+	if (ret < 0)
+		goto out;
+
+	pr_info("Using FIFO-based ABI\n");
+
+	evtchn_ops = &evtchn_ops_fifo;
+
+	register_cpu_notifier(&evtchn_fifo_cpu_notifier);
+out:
+	put_cpu();
+	return ret;
+}
diff --git a/drivers/xen/events/events_internal.h
b/drivers/xen/events/events_internal.h
index 2862e1c..677f41a 100644
--- a/drivers/xen/events/events_internal.h
+++ b/drivers/xen/events/events_internal.h
@@ -69,6 +69,7 @@ struct evtchn_ops {
 	void (*unmask)(unsigned port);
 
 	void (*handle_events)(unsigned cpu);
+	void (*resume)(void);
 };
 
 extern const struct evtchn_ops *evtchn_ops;
@@ -137,6 +138,13 @@ static inline void xen_evtchn_handle_events(unsigned cpu)
 	return evtchn_ops->handle_events(cpu);
 }
 
+static inline void xen_evtchn_resume(void)
+{
+	if (evtchn_ops->resume)
+		evtchn_ops->resume();
+}
+
 void xen_evtchn_2l_init(void);
+int xen_evtchn_fifo_init(void);
 
 #endif /* #ifndef __EVENTS_INTERNAL_H__ */
-- 
1.7.2.5

On 10/18/2013 10:23 AM, David Vrabel wrote:
> From: David Vrabel <david.vrabel@citrix.com>
>
> In preparation for alternative event channel ABIs, move all the
> functions accessing the shared data structures into their own file.
>
> Signed-off-by: David Vrabel <david.vrabel@citrix.com>
> ---
>   drivers/xen/events/Makefile          |    1 +
>   drivers/xen/events/events_2l.c       |  348
+++++++++++++++++++++++++++++++
>   drivers/xen/events/events_base.c     |  379
++--------------------------------
>   drivers/xen/events/events_internal.h |   74 +++++++
>   include/xen/events.h                 |    2 +
>   5 files changed, 442 insertions(+), 362 deletions(-)
>   create mode 100644 drivers/xen/events/events_2l.c
>   create mode 100644 drivers/xen/events/events_internal.h
I am not sure I see what the point is for adding irq_from_virq() --- it 
is only used once (I didn''t see it anywhere in subsequent patches but I
may have missed it). There is also no complementary set_virq_to_irq() 
(or some such) so per_cpu(virq_to_irq) is still being used explicitly, 
if that was the idea for irq_from_virq().

Other than that

Reviewed-by: Boris Ostrovsky <boris.ostrovsky@oracle.com>

-boris
>
> diff --git a/drivers/xen/events/Makefile b/drivers/xen/events/Makefile
> index f0bc607..08179fe 100644
> --- a/drivers/xen/events/Makefile
> +++ b/drivers/xen/events/Makefile
> @@ -1,3 +1,4 @@
>   obj-y += events.o
>   
>   events-y += events_base.o
> +events-y += events_2l.o
> diff --git a/drivers/xen/events/events_2l.c
b/drivers/xen/events/events_2l.c
> new file mode 100644
> index 0000000..a77e98d
> --- /dev/null
> +++ b/drivers/xen/events/events_2l.c
> @@ -0,0 +1,348 @@
> +/*
> + * Xen event channels (2-level ABI)
> + *
> + * Jeremy Fitzhardinge <jeremy@xensource.com>, XenSource Inc, 2007
> + */
> +
> +#define pr_fmt(fmt) "xen:" KBUILD_MODNAME ": " fmt
> +
> +#include <linux/linkage.h>
> +#include <linux/interrupt.h>
> +#include <linux/irq.h>
> +#include <linux/module.h>
> +
> +#include <asm/sync_bitops.h>
> +#include <asm/xen/hypercall.h>
> +#include <asm/xen/hypervisor.h>
> +
> +#include <xen/xen.h>
> +#include <xen/xen-ops.h>
> +#include <xen/events.h>
> +#include <xen/interface/xen.h>
> +#include <xen/interface/event_channel.h>
> +
> +#include "events_internal.h"
> +
> +/*
> + * Note sizeof(xen_ulong_t) can be more than sizeof(unsigned long). Be
> + * careful to only use bitops which allow for this (e.g
> + * test_bit/find_first_bit and friends but not __ffs) and to pass
> + * BITS_PER_EVTCHN_WORD as the bitmask length.
> + */
> +#define BITS_PER_EVTCHN_WORD (sizeof(xen_ulong_t)*8)
> +/*
> + * Make a bitmask (i.e. unsigned long *) of a xen_ulong_t
> + * array. Primarily to avoid long lines (hence the terse name).
> + */
> +#define BM(x) (unsigned long *)(x)
> +/* Find the first set bit in a evtchn mask */
> +#define EVTCHN_FIRST_BIT(w) find_first_bit(BM(&(w)),
BITS_PER_EVTCHN_WORD)
> +
> +static DEFINE_PER_CPU(xen_ulong_t
[NR_EVENT_CHANNELS/BITS_PER_EVTCHN_WORD],
> +		      cpu_evtchn_mask);
> +
> +void xen_evtchn_port_bind_to_cpu(struct irq_info *info, int cpu)
> +{
> +	clear_bit(info->evtchn, BM(per_cpu(cpu_evtchn_mask, info->cpu)));
> +	set_bit(info->evtchn, BM(per_cpu(cpu_evtchn_mask, cpu)));
> +}
> +
> +void clear_evtchn(int port)
> +{
> +	struct shared_info *s = HYPERVISOR_shared_info;
> +	sync_clear_bit(port, BM(&s->evtchn_pending[0]));
> +}
> +
> +void set_evtchn(int port)
> +{
> +	struct shared_info *s = HYPERVISOR_shared_info;
> +	sync_set_bit(port, BM(&s->evtchn_pending[0]));
> +}
> +
> +int test_evtchn(int port)
> +{
> +	struct shared_info *s = HYPERVISOR_shared_info;
> +	return sync_test_bit(port, BM(&s->evtchn_pending[0]));
> +}
> +
> +int test_and_set_mask(int port)
> +{
> +	struct shared_info *s = HYPERVISOR_shared_info;
> +	return sync_test_and_set_bit(port, BM(&s->evtchn_mask[0]));
> +}
> +
> +void mask_evtchn(int port)
> +{
> +	struct shared_info *s = HYPERVISOR_shared_info;
> +	sync_set_bit(port, BM(&s->evtchn_mask[0]));
> +}
> +
> +void unmask_evtchn(int port)
> +{
> +	struct shared_info *s = HYPERVISOR_shared_info;
> +	unsigned int cpu = get_cpu();
> +	int do_hypercall = 0, evtchn_pending = 0;
> +
> +	BUG_ON(!irqs_disabled());
> +
> +	if (unlikely((cpu != cpu_from_evtchn(port))))
> +		do_hypercall = 1;
> +	else {
> +		/*
> +		 * Need to clear the mask before checking pending to
> +		 * avoid a race with an event becoming pending.
> +		 *
> +		 * EVTCHNOP_unmask will only trigger an upcall if the
> +		 * mask bit was set, so if a hypercall is needed
> +		 * remask the event.
> +		 */
> +		sync_clear_bit(port, BM(&s->evtchn_mask[0]));
> +		evtchn_pending = sync_test_bit(port, BM(&s->evtchn_pending[0]));
> +
> +		if (unlikely(evtchn_pending && xen_hvm_domain())) {
> +			sync_set_bit(port, BM(&s->evtchn_mask[0]));
> +			do_hypercall = 1;
> +		}
> +	}
> +
> +	/* Slow path (hypercall) if this is a non-local port or if this is
> +	 * an hvm domain and an event is pending (hvm domains don''t have
> +	 * their own implementation of irq_enable). */
> +	if (do_hypercall) {
> +		struct evtchn_unmask unmask = { .port = port };
> +		(void)HYPERVISOR_event_channel_op(EVTCHNOP_unmask, &unmask);
> +	} else {
> +		struct vcpu_info *vcpu_info = __this_cpu_read(xen_vcpu);
> +
> +		/*
> +		 * The following is basically the equivalent of
> +		 * ''hw_resend_irq''. Just like a real IO-APIC we
''lose
> +		 * the interrupt edge'' if the channel is masked.
> +		 */
> +		if (evtchn_pending &&
> +		    !sync_test_and_set_bit(port / BITS_PER_EVTCHN_WORD,
> +					   BM(&vcpu_info->evtchn_pending_sel)))
> +			vcpu_info->evtchn_upcall_pending = 1;
> +	}
> +
> +	put_cpu();
> +}
> +
> +static DEFINE_PER_CPU(unsigned int, current_word_idx);
> +static DEFINE_PER_CPU(unsigned int, current_bit_idx);
> +
> +/*
> + * Mask out the i least significant bits of w
> + */
> +#define MASK_LSBS(w, i) (w & ((~((xen_ulong_t)0UL)) << i))
> +
> +static inline xen_ulong_t active_evtchns(unsigned int cpu,
> +					 struct shared_info *sh,
> +					 unsigned int idx)
> +{
> +	return sh->evtchn_pending[idx] &
> +		per_cpu(cpu_evtchn_mask, cpu)[idx] &
> +		~sh->evtchn_mask[idx];
> +}
> +
> +/*
> + * Search the CPU''s pending events bitmasks.  For each one found,
map
> + * the event number to an irq, and feed it into do_IRQ() for handling.
> + *
> + * Xen uses a two-level bitmap to speed searching.  The first level is
> + * a bitset of words which contain pending event bits.  The second
> + * level is a bitset of pending events themselves.
> + */
> +void xen_evtchn_handle_events(int cpu)
> +{
> +	int irq;
> +	xen_ulong_t pending_words;
> +	xen_ulong_t pending_bits;
> +	int start_word_idx, start_bit_idx;
> +	int word_idx, bit_idx;
> +	int i;
> +	struct irq_desc *desc;
> +	struct shared_info *s = HYPERVISOR_shared_info;
> +	struct vcpu_info *vcpu_info = __this_cpu_read(xen_vcpu);
> +
> +	/* Timer interrupt has highest priority. */
> +	irq = irq_from_virq(cpu, VIRQ_TIMER);
> +	if (irq != -1) {
> +		unsigned int evtchn = evtchn_from_irq(irq);
> +		word_idx = evtchn / BITS_PER_LONG;
> +		bit_idx = evtchn % BITS_PER_LONG;
> +		if (active_evtchns(cpu, s, word_idx) & (1ULL << bit_idx)) {
> +			desc = irq_to_desc(irq);
> +			if (desc)
> +				generic_handle_irq_desc(irq, desc);
> +		}
> +	}
> +
> +	/*
> +	 * Master flag must be cleared /before/ clearing
> +	 * selector flag. xchg_xen_ulong must contain an
> +	 * appropriate barrier.
> +	 */
> +	pending_words = xchg_xen_ulong(&vcpu_info->evtchn_pending_sel, 0);
> +
> +	start_word_idx = __this_cpu_read(current_word_idx);
> +	start_bit_idx = __this_cpu_read(current_bit_idx);
> +
> +	word_idx = start_word_idx;
> +
> +	for (i = 0; pending_words != 0; i++) {
> +		xen_ulong_t words;
> +
> +		words = MASK_LSBS(pending_words, word_idx);
> +
> +		/*
> +		 * If we masked out all events, wrap to beginning.
> +		 */
> +		if (words == 0) {
> +			word_idx = 0;
> +			bit_idx = 0;
> +			continue;
> +		}
> +		word_idx = EVTCHN_FIRST_BIT(words);
> +
> +		pending_bits = active_evtchns(cpu, s, word_idx);
> +		bit_idx = 0; /* usually scan entire word from start */
> +		/*
> +		 * We scan the starting word in two parts.
> +		 *
> +		 * 1st time: start in the middle, scanning the
> +		 * upper bits.
> +		 *
> +		 * 2nd time: scan the whole word (not just the
> +		 * parts skipped in the first pass) -- if an
> +		 * event in the previously scanned bits is
> +		 * pending again it would just be scanned on
> +		 * the next loop anyway.
> +		 */
> +		if (word_idx == start_word_idx) {
> +			if (i == 0)
> +				bit_idx = start_bit_idx;
> +		}
> +
> +		do {
> +			xen_ulong_t bits;
> +			int port;
> +
> +			bits = MASK_LSBS(pending_bits, bit_idx);
> +
> +			/* If we masked out all events, move on. */
> +			if (bits == 0)
> +				break;
> +
> +			bit_idx = EVTCHN_FIRST_BIT(bits);
> +
> +			/* Process port. */
> +			port = (word_idx * BITS_PER_EVTCHN_WORD) + bit_idx;
> +			irq = evtchn_to_irq[port];
> +
> +			if (irq != -1) {
> +				desc = irq_to_desc(irq);
> +				if (desc)
> +					generic_handle_irq_desc(irq, desc);
> +			}
> +
> +			bit_idx = (bit_idx + 1) % BITS_PER_EVTCHN_WORD;
> +
> +			/* Next caller starts at last processed + 1 */
> +			__this_cpu_write(current_word_idx,
> +					 bit_idx ? word_idx :
> +					 (word_idx+1) % BITS_PER_EVTCHN_WORD);
> +			__this_cpu_write(current_bit_idx, bit_idx);
> +		} while (bit_idx != 0);
> +
> +		/* Scan start_l1i twice; all others once. */
> +		if ((word_idx != start_word_idx) || (i != 0))
> +			pending_words &= ~(1UL << word_idx);
> +
> +		word_idx = (word_idx + 1) % BITS_PER_EVTCHN_WORD;
> +	}
> +}
> +
> +irqreturn_t xen_debug_interrupt(int irq, void *dev_id)
> +{
> +	struct shared_info *sh = HYPERVISOR_shared_info;
> +	int cpu = smp_processor_id();
> +	xen_ulong_t *cpu_evtchn = per_cpu(cpu_evtchn_mask, cpu);
> +	int i;
> +	unsigned long flags;
> +	static DEFINE_SPINLOCK(debug_lock);
> +	struct vcpu_info *v;
> +
> +	spin_lock_irqsave(&debug_lock, flags);
> +
> +	printk("\nvcpu %d\n  ", cpu);
> +
> +	for_each_online_cpu(i) {
> +		int pending;
> +		v = per_cpu(xen_vcpu, i);
> +		pending = (get_irq_regs() && i == cpu)
> +			? xen_irqs_disabled(get_irq_regs())
> +			: v->evtchn_upcall_mask;
> +		printk("%d: masked=%d pending=%d event_sel
%0*"PRI_xen_ulong"\n  ", i,
> +		       pending, v->evtchn_upcall_pending,
> +		       (int)(sizeof(v->evtchn_pending_sel)*2),
> +		       v->evtchn_pending_sel);
> +	}
> +	v = per_cpu(xen_vcpu, cpu);
> +
> +	printk("\npending:\n   ");
> +	for (i = ARRAY_SIZE(sh->evtchn_pending)-1; i >= 0; i--)
> +		printk("%0*"PRI_xen_ulong"%s",
> +		       (int)sizeof(sh->evtchn_pending[0])*2,
> +		       sh->evtchn_pending[i],
> +		       i % 8 == 0 ? "\n   " : " ");
> +	printk("\nglobal mask:\n   ");
> +	for (i = ARRAY_SIZE(sh->evtchn_mask)-1; i >= 0; i--)
> +		printk("%0*"PRI_xen_ulong"%s",
> +		       (int)(sizeof(sh->evtchn_mask[0])*2),
> +		       sh->evtchn_mask[i],
> +		       i % 8 == 0 ? "\n   " : " ");
> +
> +	printk("\nglobally unmasked:\n   ");
> +	for (i = ARRAY_SIZE(sh->evtchn_mask)-1; i >= 0; i--)
> +		printk("%0*"PRI_xen_ulong"%s",
> +		       (int)(sizeof(sh->evtchn_mask[0])*2),
> +		       sh->evtchn_pending[i] & ~sh->evtchn_mask[i],
> +		       i % 8 == 0 ? "\n   " : " ");
> +
> +	printk("\nlocal cpu%d mask:\n   ", cpu);
> +	for (i = (NR_EVENT_CHANNELS/BITS_PER_EVTCHN_WORD)-1; i >= 0; i--)
> +		printk("%0*"PRI_xen_ulong"%s",
(int)(sizeof(cpu_evtchn[0])*2),
> +		       cpu_evtchn[i],
> +		       i % 8 == 0 ? "\n   " : " ");
> +
> +	printk("\nlocally unmasked:\n   ");
> +	for (i = ARRAY_SIZE(sh->evtchn_mask)-1; i >= 0; i--) {
> +		xen_ulong_t pending = sh->evtchn_pending[i]
> +			& ~sh->evtchn_mask[i]
> +			& cpu_evtchn[i];
> +		printk("%0*"PRI_xen_ulong"%s",
> +		       (int)(sizeof(sh->evtchn_mask[0])*2),
> +		       pending, i % 8 == 0 ? "\n   " : " ");
> +	}
> +
> +	printk("\npending list:\n");
> +	for (i = 0; i < NR_EVENT_CHANNELS; i++) {
> +		if (sync_test_bit(i, BM(sh->evtchn_pending))) {
> +			int word_idx = i / BITS_PER_EVTCHN_WORD;
> +			printk("  %d: event %d -> irq %d%s%s%s\n",
> +			       cpu_from_evtchn(i), i,
> +			       evtchn_to_irq[i],
> +			       sync_test_bit(word_idx, BM(&v->evtchn_pending_sel))
> +			       ? "" : " l2-clear",
> +			       !sync_test_bit(i, BM(sh->evtchn_mask))
> +			       ? "" : " globally-masked",
> +			       sync_test_bit(i, BM(cpu_evtchn))
> +			       ? "" : " locally-masked");
> +		}
> +	}
> +
> +	spin_unlock_irqrestore(&debug_lock, flags);
> +
> +	return IRQ_HANDLED;
> +}
> diff --git a/drivers/xen/events/events_base.c
b/drivers/xen/events/events_base.c
> index fec5da4..8771b74 100644
> --- a/drivers/xen/events/events_base.c
> +++ b/drivers/xen/events/events_base.c
> @@ -59,6 +59,8 @@
>   #include <xen/interface/vcpu.h>
>   #include <asm/hw_irq.h>
>   
> +#include "events_internal.h"
> +
>   /*
>    * This lock protects updates to the following mapping and
reference-count
>    * arrays. The lock does not need to be acquired to read the mapping
tables.
> @@ -73,72 +75,12 @@ static DEFINE_PER_CPU(int [NR_VIRQS], virq_to_irq) =
{[0 ... NR_VIRQS-1] = -1};
>   /* IRQ <-> IPI mapping */
>   static DEFINE_PER_CPU(int [XEN_NR_IPIS], ipi_to_irq) = {[0 ...
XEN_NR_IPIS-1] = -1};
>   
> -/* Interrupt types. */
> -enum xen_irq_type {
> -	IRQT_UNBOUND = 0,
> -	IRQT_PIRQ,
> -	IRQT_VIRQ,
> -	IRQT_IPI,
> -	IRQT_EVTCHN
> -};
> -
> -/*
> - * Packed IRQ information:
> - * type - enum xen_irq_type
> - * event channel - irq->event channel mapping
> - * cpu - cpu this event channel is bound to
> - * index - type-specific information:
> - *    PIRQ - physical IRQ, GSI, flags, and owner domain
> - *    VIRQ - virq number
> - *    IPI - IPI vector
> - *    EVTCHN -
> - */
> -struct irq_info {
> -	struct list_head list;
> -	int refcnt;
> -	enum xen_irq_type type;	/* type */
> -	unsigned irq;
> -	unsigned short evtchn;	/* event channel */
> -	unsigned short cpu;	/* cpu bound */
> -
> -	union {
> -		unsigned short virq;
> -		enum ipi_vector ipi;
> -		struct {
> -			unsigned short pirq;
> -			unsigned short gsi;
> -			unsigned char flags;
> -			uint16_t domid;
> -		} pirq;
> -	} u;
> -};
> -#define PIRQ_NEEDS_EOI	(1 << 0)
> -#define PIRQ_SHAREABLE	(1 << 1)
> -
> -static int *evtchn_to_irq;
> +int *evtchn_to_irq;
>   #ifdef CONFIG_X86
>   static unsigned long *pirq_eoi_map;
>   #endif
>   static bool (*pirq_needs_eoi)(unsigned irq);
>   
> -/*
> - * Note sizeof(xen_ulong_t) can be more than sizeof(unsigned long). Be
> - * careful to only use bitops which allow for this (e.g
> - * test_bit/find_first_bit and friends but not __ffs) and to pass
> - * BITS_PER_EVTCHN_WORD as the bitmask length.
> - */
> -#define BITS_PER_EVTCHN_WORD (sizeof(xen_ulong_t)*8)
> -/*
> - * Make a bitmask (i.e. unsigned long *) of a xen_ulong_t
> - * array. Primarily to avoid long lines (hence the terse name).
> - */
> -#define BM(x) (unsigned long *)(x)
> -/* Find the first set bit in a evtchn mask */
> -#define EVTCHN_FIRST_BIT(w) find_first_bit(BM(&(w)),
BITS_PER_EVTCHN_WORD)
> -
> -static DEFINE_PER_CPU(xen_ulong_t
[NR_EVENT_CHANNELS/BITS_PER_EVTCHN_WORD],
> -		      cpu_evtchn_mask);
> -
>   /* Xen will never allocate port zero for any purpose. */
>   #define VALID_EVTCHN(chn)	((chn) != 0)
>   
> @@ -149,7 +91,7 @@ static void enable_dynirq(struct irq_data *data);
>   static void disable_dynirq(struct irq_data *data);
>   
>   /* Get info for IRQ */
> -static struct irq_info *info_for_irq(unsigned irq)
> +struct irq_info *info_for_irq(unsigned irq)
>   {
>   	return irq_get_handler_data(irq);
>   }
> @@ -230,7 +172,7 @@ static void xen_irq_info_pirq_init(unsigned irq,
>   /*
>    * Accessors for packed IRQ information.
>    */
> -static unsigned int evtchn_from_irq(unsigned irq)
> +unsigned int evtchn_from_irq(unsigned irq)
>   {
>   	if (unlikely(WARN(irq < 0 || irq >= nr_irqs, "Invalid irq
%d!\n", irq)))
>   		return 0;
> @@ -244,6 +186,11 @@ unsigned irq_from_evtchn(unsigned int evtchn)
>   }
>   EXPORT_SYMBOL_GPL(irq_from_evtchn);
>   
> +int irq_from_virq(unsigned int cpu, unsigned int virq)
> +{
> +	return per_cpu(virq_to_irq, cpu)[virq];
> +}
> +
>   static enum ipi_vector ipi_from_irq(unsigned irq)
>   {
>   	struct irq_info *info = info_for_irq(irq);
> @@ -279,12 +226,12 @@ static enum xen_irq_type type_from_irq(unsigned irq)
>   	return info_for_irq(irq)->type;
>   }
>   
> -static unsigned cpu_from_irq(unsigned irq)
> +unsigned cpu_from_irq(unsigned irq)
>   {
>   	return info_for_irq(irq)->cpu;
>   }
>   
> -static unsigned int cpu_from_evtchn(unsigned int evtchn)
> +unsigned int cpu_from_evtchn(unsigned int evtchn)
>   {
>   	int irq = evtchn_to_irq[evtchn];
>   	unsigned ret = 0;
> @@ -310,55 +257,21 @@ static bool pirq_needs_eoi_flag(unsigned irq)
>   	return info->u.pirq.flags & PIRQ_NEEDS_EOI;
>   }
>   
> -static inline xen_ulong_t active_evtchns(unsigned int cpu,
> -					 struct shared_info *sh,
> -					 unsigned int idx)
> -{
> -	return sh->evtchn_pending[idx] &
> -		per_cpu(cpu_evtchn_mask, cpu)[idx] &
> -		~sh->evtchn_mask[idx];
> -}
> -
>   static void bind_evtchn_to_cpu(unsigned int chn, unsigned int cpu)
>   {
>   	int irq = evtchn_to_irq[chn];
> +	struct irq_info *info = info_for_irq(irq);
>   
>   	BUG_ON(irq == -1);
>   #ifdef CONFIG_SMP
>   	cpumask_copy(irq_to_desc(irq)->irq_data.affinity, cpumask_of(cpu));
>   #endif
>   
> -	clear_bit(chn, BM(per_cpu(cpu_evtchn_mask, cpu_from_irq(irq))));
> -	set_bit(chn, BM(per_cpu(cpu_evtchn_mask, cpu)));
> +	xen_evtchn_port_bind_to_cpu(info, cpu);
>   
> -	info_for_irq(irq)->cpu = cpu;
> -}
> -
> -static inline void clear_evtchn(int port)
> -{
> -	struct shared_info *s = HYPERVISOR_shared_info;
> -	sync_clear_bit(port, BM(&s->evtchn_pending[0]));
> -}
> -
> -static inline void set_evtchn(int port)
> -{
> -	struct shared_info *s = HYPERVISOR_shared_info;
> -	sync_set_bit(port, BM(&s->evtchn_pending[0]));
> -}
> -
> -static inline int test_evtchn(int port)
> -{
> -	struct shared_info *s = HYPERVISOR_shared_info;
> -	return sync_test_bit(port, BM(&s->evtchn_pending[0]));
> -}
> -
> -static inline int test_and_set_mask(int port)
> -{
> -	struct shared_info *s = HYPERVISOR_shared_info;
> -	return sync_test_and_set_bit(port, BM(&s->evtchn_mask[0]));
> +	info->cpu = cpu;
>   }
>   
> -
>   /**
>    * notify_remote_via_irq - send event to remote end of event channel via
irq
>    * @irq: irq of event channel to send event to
> @@ -376,63 +289,6 @@ void notify_remote_via_irq(int irq)
>   }
>   EXPORT_SYMBOL_GPL(notify_remote_via_irq);
>   
> -static void mask_evtchn(int port)
> -{
> -	struct shared_info *s = HYPERVISOR_shared_info;
> -	sync_set_bit(port, BM(&s->evtchn_mask[0]));
> -}
> -
> -static void unmask_evtchn(int port)
> -{
> -	struct shared_info *s = HYPERVISOR_shared_info;
> -	unsigned int cpu = get_cpu();
> -	int do_hypercall = 0, evtchn_pending = 0;
> -
> -	BUG_ON(!irqs_disabled());
> -
> -	if (unlikely((cpu != cpu_from_evtchn(port))))
> -		do_hypercall = 1;
> -	else {
> -		/*
> -		 * Need to clear the mask before checking pending to
> -		 * avoid a race with an event becoming pending.
> -		 *
> -		 * EVTCHNOP_unmask will only trigger an upcall if the
> -		 * mask bit was set, so if a hypercall is needed
> -		 * remask the event.
> -		 */
> -		sync_clear_bit(port, BM(&s->evtchn_mask[0]));
> -		evtchn_pending = sync_test_bit(port, BM(&s->evtchn_pending[0]));
> -
> -		if (unlikely(evtchn_pending && xen_hvm_domain())) {
> -			sync_set_bit(port, BM(&s->evtchn_mask[0]));
> -			do_hypercall = 1;
> -		}
> -	}
> -
> -	/* Slow path (hypercall) if this is a non-local port or if this is
> -	 * an hvm domain and an event is pending (hvm domains don''t have
> -	 * their own implementation of irq_enable). */
> -	if (do_hypercall) {
> -		struct evtchn_unmask unmask = { .port = port };
> -		(void)HYPERVISOR_event_channel_op(EVTCHNOP_unmask, &unmask);
> -	} else {
> -		struct vcpu_info *vcpu_info = __this_cpu_read(xen_vcpu);
> -
> -		/*
> -		 * The following is basically the equivalent of
> -		 * ''hw_resend_irq''. Just like a real IO-APIC we
''lose
> -		 * the interrupt edge'' if the channel is masked.
> -		 */
> -		if (evtchn_pending &&
> -		    !sync_test_and_set_bit(port / BITS_PER_EVTCHN_WORD,
> -					   BM(&vcpu_info->evtchn_pending_sel)))
> -			vcpu_info->evtchn_upcall_pending = 1;
> -	}
> -
> -	put_cpu();
> -}
> -
>   static void xen_irq_init(unsigned irq)
>   {
>   	struct irq_info *info;
> @@ -1216,222 +1072,21 @@ void xen_send_IPI_one(unsigned int cpu, enum
ipi_vector vector)
>   	notify_remote_via_irq(irq);
>   }
>   
> -irqreturn_t xen_debug_interrupt(int irq, void *dev_id)
> -{
> -	struct shared_info *sh = HYPERVISOR_shared_info;
> -	int cpu = smp_processor_id();
> -	xen_ulong_t *cpu_evtchn = per_cpu(cpu_evtchn_mask, cpu);
> -	int i;
> -	unsigned long flags;
> -	static DEFINE_SPINLOCK(debug_lock);
> -	struct vcpu_info *v;
> -
> -	spin_lock_irqsave(&debug_lock, flags);
> -
> -	printk("\nvcpu %d\n  ", cpu);
> -
> -	for_each_online_cpu(i) {
> -		int pending;
> -		v = per_cpu(xen_vcpu, i);
> -		pending = (get_irq_regs() && i == cpu)
> -			? xen_irqs_disabled(get_irq_regs())
> -			: v->evtchn_upcall_mask;
> -		printk("%d: masked=%d pending=%d event_sel
%0*"PRI_xen_ulong"\n  ", i,
> -		       pending, v->evtchn_upcall_pending,
> -		       (int)(sizeof(v->evtchn_pending_sel)*2),
> -		       v->evtchn_pending_sel);
> -	}
> -	v = per_cpu(xen_vcpu, cpu);
> -
> -	printk("\npending:\n   ");
> -	for (i = ARRAY_SIZE(sh->evtchn_pending)-1; i >= 0; i--)
> -		printk("%0*"PRI_xen_ulong"%s",
> -		       (int)sizeof(sh->evtchn_pending[0])*2,
> -		       sh->evtchn_pending[i],
> -		       i % 8 == 0 ? "\n   " : " ");
> -	printk("\nglobal mask:\n   ");
> -	for (i = ARRAY_SIZE(sh->evtchn_mask)-1; i >= 0; i--)
> -		printk("%0*"PRI_xen_ulong"%s",
> -		       (int)(sizeof(sh->evtchn_mask[0])*2),
> -		       sh->evtchn_mask[i],
> -		       i % 8 == 0 ? "\n   " : " ");
> -
> -	printk("\nglobally unmasked:\n   ");
> -	for (i = ARRAY_SIZE(sh->evtchn_mask)-1; i >= 0; i--)
> -		printk("%0*"PRI_xen_ulong"%s",
> -		       (int)(sizeof(sh->evtchn_mask[0])*2),
> -		       sh->evtchn_pending[i] & ~sh->evtchn_mask[i],
> -		       i % 8 == 0 ? "\n   " : " ");
> -
> -	printk("\nlocal cpu%d mask:\n   ", cpu);
> -	for (i = (NR_EVENT_CHANNELS/BITS_PER_EVTCHN_WORD)-1; i >= 0; i--)
> -		printk("%0*"PRI_xen_ulong"%s",
(int)(sizeof(cpu_evtchn[0])*2),
> -		       cpu_evtchn[i],
> -		       i % 8 == 0 ? "\n   " : " ");
> -
> -	printk("\nlocally unmasked:\n   ");
> -	for (i = ARRAY_SIZE(sh->evtchn_mask)-1; i >= 0; i--) {
> -		xen_ulong_t pending = sh->evtchn_pending[i]
> -			& ~sh->evtchn_mask[i]
> -			& cpu_evtchn[i];
> -		printk("%0*"PRI_xen_ulong"%s",
> -		       (int)(sizeof(sh->evtchn_mask[0])*2),
> -		       pending, i % 8 == 0 ? "\n   " : " ");
> -	}
> -
> -	printk("\npending list:\n");
> -	for (i = 0; i < NR_EVENT_CHANNELS; i++) {
> -		if (sync_test_bit(i, BM(sh->evtchn_pending))) {
> -			int word_idx = i / BITS_PER_EVTCHN_WORD;
> -			printk("  %d: event %d -> irq %d%s%s%s\n",
> -			       cpu_from_evtchn(i), i,
> -			       evtchn_to_irq[i],
> -			       sync_test_bit(word_idx, BM(&v->evtchn_pending_sel))
> -					     ? "" : " l2-clear",
> -			       !sync_test_bit(i, BM(sh->evtchn_mask))
> -					     ? "" : " globally-masked",
> -			       sync_test_bit(i, BM(cpu_evtchn))
> -					     ? "" : " locally-masked");
> -		}
> -	}
> -
> -	spin_unlock_irqrestore(&debug_lock, flags);
> -
> -	return IRQ_HANDLED;
> -}
> -
>   static DEFINE_PER_CPU(unsigned, xed_nesting_count);
> -static DEFINE_PER_CPU(unsigned int, current_word_idx);
> -static DEFINE_PER_CPU(unsigned int, current_bit_idx);
>   
> -/*
> - * Mask out the i least significant bits of w
> - */
> -#define MASK_LSBS(w, i) (w & ((~((xen_ulong_t)0UL)) << i))
> -
> -/*
> - * Search the CPUs pending events bitmasks.  For each one found, map
> - * the event number to an irq, and feed it into do_IRQ() for
> - * handling.
> - *
> - * Xen uses a two-level bitmap to speed searching.  The first level is
> - * a bitset of words which contain pending event bits.  The second
> - * level is a bitset of pending events themselves.
> - */
>   static void __xen_evtchn_do_upcall(void)
>   {
> -	int start_word_idx, start_bit_idx;
> -	int word_idx, bit_idx;
> -	int i, irq;
> -	int cpu = get_cpu();
> -	struct shared_info *s = HYPERVISOR_shared_info;
>   	struct vcpu_info *vcpu_info = __this_cpu_read(xen_vcpu);
> +	int cpu = get_cpu();
>   	unsigned count;
>   
>   	do {
> -		xen_ulong_t pending_words;
> -		xen_ulong_t pending_bits;
> -		struct irq_desc *desc;
> -
>   		vcpu_info->evtchn_upcall_pending = 0;
>   
>   		if (__this_cpu_inc_return(xed_nesting_count) - 1)
>   			goto out;
>   
> -		/*
> -		 * Master flag must be cleared /before/ clearing
> -		 * selector flag. xchg_xen_ulong must contain an
> -		 * appropriate barrier.
> -		 */
> -		if ((irq = per_cpu(virq_to_irq, cpu)[VIRQ_TIMER]) != -1) {
> -			int evtchn = evtchn_from_irq(irq);
> -			word_idx = evtchn / BITS_PER_LONG;
> -			pending_bits = evtchn % BITS_PER_LONG;
> -			if (active_evtchns(cpu, s, word_idx) & (1ULL <<
pending_bits)) {
> -				desc = irq_to_desc(irq);
> -				if (desc)
> -					generic_handle_irq_desc(irq, desc);
> -			}
> -		}
> -
> -		pending_words = xchg_xen_ulong(&vcpu_info->evtchn_pending_sel,
0);
> -
> -		start_word_idx = __this_cpu_read(current_word_idx);
> -		start_bit_idx = __this_cpu_read(current_bit_idx);
> -
> -		word_idx = start_word_idx;
> -
> -		for (i = 0; pending_words != 0; i++) {
> -			xen_ulong_t words;
> -
> -			words = MASK_LSBS(pending_words, word_idx);
> -
> -			/*
> -			 * If we masked out all events, wrap to beginning.
> -			 */
> -			if (words == 0) {
> -				word_idx = 0;
> -				bit_idx = 0;
> -				continue;
> -			}
> -			word_idx = EVTCHN_FIRST_BIT(words);
> -
> -			pending_bits = active_evtchns(cpu, s, word_idx);
> -			bit_idx = 0; /* usually scan entire word from start */
> -			/*
> -			 * We scan the starting word in two parts.
> -			 *
> -			 * 1st time: start in the middle, scanning the
> -			 * upper bits.
> -			 *
> -			 * 2nd time: scan the whole word (not just the
> -			 * parts skipped in the first pass) -- if an
> -			 * event in the previously scanned bits is
> -			 * pending again it would just be scanned on
> -			 * the next loop anyway.
> -			 */
> -			if (word_idx == start_word_idx) {
> -				if (i == 0)
> -					bit_idx = start_bit_idx;
> -			}
> -
> -			do {
> -				xen_ulong_t bits;
> -				int port;
> -
> -				bits = MASK_LSBS(pending_bits, bit_idx);
> -
> -				/* If we masked out all events, move on. */
> -				if (bits == 0)
> -					break;
> -
> -				bit_idx = EVTCHN_FIRST_BIT(bits);
> -
> -				/* Process port. */
> -				port = (word_idx * BITS_PER_EVTCHN_WORD) + bit_idx;
> -				irq = evtchn_to_irq[port];
> -
> -				if (irq != -1) {
> -					desc = irq_to_desc(irq);
> -					if (desc)
> -						generic_handle_irq_desc(irq, desc);
> -				}
> -
> -				bit_idx = (bit_idx + 1) % BITS_PER_EVTCHN_WORD;
> -
> -				/* Next caller starts at last processed + 1 */
> -				__this_cpu_write(current_word_idx,
> -						 bit_idx ? word_idx :
> -						 (word_idx+1) % BITS_PER_EVTCHN_WORD);
> -				__this_cpu_write(current_bit_idx, bit_idx);
> -			} while (bit_idx != 0);
> -
> -			/* Scan start_l1i twice; all others once. */
> -			if ((word_idx != start_word_idx) || (i != 0))
> -				pending_words &= ~(1UL << word_idx);
> -
> -			word_idx = (word_idx + 1) % BITS_PER_EVTCHN_WORD;
> -		}
> +		xen_evtchn_handle_events(cpu);
>   
>   		BUG_ON(!irqs_disabled());
>   
> diff --git a/drivers/xen/events/events_internal.h
b/drivers/xen/events/events_internal.h
> new file mode 100644
> index 0000000..79ac70b
> --- /dev/null
> +++ b/drivers/xen/events/events_internal.h
> @@ -0,0 +1,74 @@
> +/*
> + * Xen Event Channels (internal header)
> + *
> + * Copyright (C) 2013 Citrix Systems R&D Ltd.
> + *
> + * This source code is licensed under the GNU General Public License,
> + * Version 2 or later.  See the file COPYING for more details.
> + */
> +#ifndef __EVENTS_INTERNAL_H__
> +#define __EVENTS_INTERNAL_H__
> +
> +/* Interrupt types. */
> +enum xen_irq_type {
> +	IRQT_UNBOUND = 0,
> +	IRQT_PIRQ,
> +	IRQT_VIRQ,
> +	IRQT_IPI,
> +	IRQT_EVTCHN
> +};
> +
> +/*
> + * Packed IRQ information:
> + * type - enum xen_irq_type
> + * event channel - irq->event channel mapping
> + * cpu - cpu this event channel is bound to
> + * index - type-specific information:
> + *    PIRQ - vector, with MSB being "needs EIO", or physical IRQ
of the HVM
> + *           guest, or GSI (real passthrough IRQ) of the device.
> + *    VIRQ - virq number
> + *    IPI - IPI vector
> + *    EVTCHN -
> + */
> +struct irq_info {
> +	struct list_head list;
> +	int refcnt;
> +	enum xen_irq_type type;	/* type */
> +	unsigned irq;
> +	unsigned short evtchn;	/* event channel */
> +	unsigned short cpu;	/* cpu bound */
> +
> +	union {
> +		unsigned short virq;
> +		enum ipi_vector ipi;
> +		struct {
> +			unsigned short pirq;
> +			unsigned short gsi;
> +			unsigned char vector;
> +			unsigned char flags;
> +			uint16_t domid;
> +		} pirq;
> +	} u;
> +};
> +
> +#define PIRQ_NEEDS_EOI	(1 << 0)
> +#define PIRQ_SHAREABLE	(1 << 1)
> +
> +extern int *evtchn_to_irq;
> +
> +struct irq_info *info_for_irq(unsigned irq);
> +unsigned cpu_from_irq(unsigned irq);
> +unsigned cpu_from_evtchn(unsigned int evtchn);
> +
> +void xen_evtchn_port_bind_to_cpu(struct irq_info *info, int cpu);
> +
> +void clear_evtchn(int port);
> +void set_evtchn(int port);
> +int test_evtchn(int port);
> +int test_and_set_mask(int port);
> +void mask_evtchn(int port);
> +void unmask_evtchn(int port);
> +
> +void xen_evtchn_handle_events(int cpu);
> +
> +#endif /* #ifndef __EVENTS_INTERNAL_H__ */
> diff --git a/include/xen/events.h b/include/xen/events.h
> index c9ea10e..32ae0f2 100644
> --- a/include/xen/events.h
> +++ b/include/xen/events.h
> @@ -73,6 +73,8 @@ void xen_poll_irq_timeout(int irq, u64 timeout);
>   
>   /* Determine the IRQ which is bound to an event channel */
>   unsigned irq_from_evtchn(unsigned int evtchn);
> +int irq_from_virq(unsigned int cpu, unsigned int virq);
> +unsigned int evtchn_from_irq(unsigned irq);
>   
>   /* Xen HVM evtchn vector callback */
>   void xen_hvm_callback_vector(void);

On 10/18/2013 10:23 AM, David Vrabel wrote:
> This is the complete Linux guest-side implementation of the FIFO-based
> event channel ABI described in this design document:
With one more comment for 06/16,

Reviewed-by: Boris Ostrovsky <boris.ostrovsky@oracle.com>
>
>    http://xenbits.xen.org/people/dvrabel/event-channels-F.pdf
>
> The Xen implementation is now available in xen-unstable.
>
> Note that __startup_pirq() was never ideal as failure when binding a
> PIRQ to an event channel cannot be propagated to the calling driver
> since the irq_startup callback cannot return an error.  This series
> adds another (very unlikely) failure point to __startup_pirq().
>
> I have a half-bakedpatch series to refactor when PIRQs are setup and
> torn down but this won''t be ready for a while and I do not think
this
> is a prerequisite for applying the FIFO-based ABI series.
>
> Patch 1 is a obvious refactoring of common code.
>
> Patch 2-6 prepare for supporting multiple ABIs.
>
> Patch 7 adds the low-level evtchn_ops hooks.
>
> Patch 8-9 add an additional hook for ABI-specific per-port setup
> (used for expanding the event array as more event are bound).
>
> Patch 10 allows many more event channels to be supported by altering
> how the event channel to irq map is allocated.  Note that other
> factors limit the number of supported IRQs (IRQs is 8192 + 64 *
> NR_CPUS).
>
> Patch 11 is some trival refactoring.
>
> Patch 12 removes a limit on the number of event channels supported by
> the xen-evtchn driver.
>
> Patch 13 adds the hypervisor ABI.
>
> Patches 14-15 Set the priority of VIRQ_TIMER events to the highest.
>
> Patch 16 adds the FIFO-based ABI implementation.
>
> Changes in v7:
>
> - Add xen.fifo_events command line option (defaults to true).
> - Use xen_evtchn_nr_channels() in xen_evtchn driver.
> - Drop unnecessary test in evtchn_fifo_unmask()
> - Refactor irq_info setup/cleanup a bit.
>
> Changes in v6:
>
> - nlevel -> 2l to match naming in Xen.
>
> Changes in v5 (v4 not posted):
>
> - Set priority of VIRQ_TIMER.
> - Remove NR_EVENT_CHANNELS limit from xen-evtchn driver.
> - Licence drivers/xen/events/fifo.c under a dual MIT/GPLv2.
>
> Changes in v3:
>
> - Support suspend/resume by reinitializing the control blocks on resume.
> - Only init control block if one does not exist (should fix CPU
>    hotplug).
>

On Fri, Oct 18, 2013 at 03:23:10PM +0100, David Vrabel
wrote:
> This is the complete Linux guest-side implementation of the FIFO-based
> event channel ABI described in this design document:
> 
>   http://xenbits.xen.org/people/dvrabel/event-channels-F.pdf
> 
> The Xen implementation is now available in xen-unstable.
All patches here look good to me. Aka: Reviewed-by: Konrad Rzeszutek
Wilk <konrad.wilk@oracle.com>

Please if you could either provide me with a git tree with the
correct tags (so also Boris''s tags) and mine that would be the best.

Or I can slurp them one by one - but please repost with the tags.

Thanks!

On 25/10/13 14:06, Konrad Rzeszutek Wilk wrote:
> On Fri, Oct 18, 2013 at 03:23:10PM +0100, David Vrabel wrote:
>> This is the complete Linux guest-side implementation of the FIFO-based
>> event channel ABI described in this design document:
>>
>>    http://xenbits.xen.org/people/dvrabel/event-channels-F.pdf
>>
>> The Xen implementation is now available in xen-unstable.
>
> All patches here look good to me. Aka: Reviewed-by: Konrad Rzeszutek
> Wilk <konrad.wilk@oracle.com>
>
> Please if you could either provide me with a git tree with the
> correct tags (so also Boris''s tags) and mine that would be the
best.
There needs to be a revision of the ABI to correct a critical design 
flaw.  Until this is addressed this isn''t ready to be merged.

David

On Sat, Oct 26, 2013 at 12:02:13AM +0100, David Vrabel
wrote:
> On 25/10/13 14:06, Konrad Rzeszutek Wilk wrote:
> >On Fri, Oct 18, 2013 at 03:23:10PM +0100, David Vrabel wrote:
> >>This is the complete Linux guest-side implementation of the
FIFO-based
> >>event channel ABI described in this design document:
> >>
> >>   http://xenbits.xen.org/people/dvrabel/event-channels-F.pdf
> >>
> >>The Xen implementation is now available in xen-unstable.
> >
> >All patches here look good to me. Aka: Reviewed-by: Konrad Rzeszutek
> >Wilk <konrad.wilk@oracle.com>
> >
> >Please if you could either provide me with a git tree with the
> >correct tags (so also Boris''s tags) and mine that would be the
best.
> 
> There needs to be a revision of the ABI to correct a critical design
> flaw.  Until this is addressed this isn''t ready to be merged.
Could you point out what is the design flaw? Thanks.
> 
> David