Jeremy Fitzhardinge
2009-Mar-23 18:09 UTC
[Xen-devel] [PATCH 14/15] paravirtualize IO permission bitmap
From: Christophe Saout <chtephan@leto.intern.saout.de>
Impact: make ioperm bitmap work under Xen
A PV Xen guest kernel has no TSS of its own, so the IO permission
bitmap must be paravirtualized. This patch adds set_io_bitmap
as a paravirt op, and defines a native version which updates the tss,
and a Xen version which uses a hypercall.
This is much easier now that 32 and 64-bit use the same code to
manage the IO bitmap.
Signed-off-by: Christophe Saout <chtephan@leto.intern.saout.de>
Signed-off-by: Jeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com>
---
arch/x86/include/asm/paravirt.h | 9 +++++++++
arch/x86/include/asm/processor.h | 4 ++++
arch/x86/kernel/ioport.c | 34 ++++++++++++++++++++++++++--------
arch/x86/kernel/paravirt.c | 1 +
arch/x86/kernel/process.c | 27 +++++++--------------------
arch/x86/xen/enlighten.c | 16 ++++++++++++++++
6 files changed, 63 insertions(+), 28 deletions(-)
diff --git a/arch/x86/include/asm/paravirt.h b/arch/x86/include/asm/paravirt.h
index bc384be..fd2c31b 100644
--- a/arch/x86/include/asm/paravirt.h
+++ b/arch/x86/include/asm/paravirt.h
@@ -156,6 +156,8 @@ struct pv_cpu_ops {
void (*load_sp0)(struct tss_struct *tss, struct thread_struct *t);
void (*set_iopl_mask)(unsigned mask);
+ void (*set_io_bitmap)(struct thread_struct *thread,
+ int changed, unsigned long bytes_updated);
void (*wbinvd)(void);
void (*io_delay)(void);
@@ -996,11 +998,18 @@ static inline void write_idt_entry(gate_desc *dt, int
entry, const gate_desc *g)
{
PVOP_VCALL3(pv_cpu_ops.write_idt_entry, dt, entry, g);
}
+
static inline void set_iopl_mask(unsigned mask)
{
PVOP_VCALL1(pv_cpu_ops.set_iopl_mask, mask);
}
+static inline void set_io_bitmap(struct thread_struct *thread,
+ int changed, unsigned long bytes_updated)
+{
+ PVOP_VCALL3(pv_cpu_ops.set_io_bitmap, thread, changed, bytes_updated);
+}
+
/* The paravirtualized I/O functions */
static inline void slow_down_io(void)
{
diff --git a/arch/x86/include/asm/processor.h b/arch/x86/include/asm/processor.h
index 34c5237..0ed4cba 100644
--- a/arch/x86/include/asm/processor.h
+++ b/arch/x86/include/asm/processor.h
@@ -538,6 +538,9 @@ static inline void native_set_iopl_mask(unsigned mask)
#endif
}
+extern void native_set_io_bitmap(struct thread_struct *thread,
+ int changed, unsigned long updated_bytes);
+
static inline void
native_load_sp0(struct tss_struct *tss, struct thread_struct *thread)
{
@@ -579,6 +582,7 @@ static inline void load_sp0(struct tss_struct *tss,
}
#define set_iopl_mask native_set_iopl_mask
+#define set_io_bitmap native_set_io_bitmap
#endif /* CONFIG_PARAVIRT */
/*
diff --git a/arch/x86/kernel/ioport.c b/arch/x86/kernel/ioport.c
index 99c4d30..5a12c9f 100644
--- a/arch/x86/kernel/ioport.c
+++ b/arch/x86/kernel/ioport.c
@@ -30,14 +30,31 @@ static void set_bitmap(unsigned long *bitmap, unsigned int
base,
}
}
+void native_set_io_bitmap(struct thread_struct *t,
+ int changed, unsigned long bytes_updated)
+{
+ struct tss_struct *tss;
+
+ if (!bytes_updated)
+ return;
+
+ tss = &__get_cpu_var(init_tss);
+
+ /* Update the TSS: */
+ if (t->io_bitmap_ptr)
+ memcpy(tss->io_bitmap, t->io_bitmap_ptr, bytes_updated);
+ else
+ memset(tss->io_bitmap, 0xff, bytes_updated);
+}
+
/*
* this changes the io permissions bitmap in the current task.
*/
asmlinkage long sys_ioperm(unsigned long from, unsigned long num, int turn_on)
{
struct thread_struct *t = ¤t->thread;
- struct tss_struct *tss;
unsigned int i, max_long, bytes, bytes_updated;
+ int changed;
if ((from + num <= from) || (from + num > IO_BITMAP_BITS))
return -EINVAL;
@@ -58,16 +75,18 @@ asmlinkage long sys_ioperm(unsigned long from, unsigned long
num, int turn_on)
memset(bitmap, 0xff, IO_BITMAP_BYTES);
t->io_bitmap_ptr = bitmap;
set_thread_flag(TIF_IO_BITMAP);
- }
+ changed = 1;
+ } else
+ changed = 0;
/*
- * do it in the per-thread copy and in the TSS ...
+ * do it in the per-thread copy
*
- * Disable preemption via get_cpu() - we must not switch away
+ * Disable preemption - we must not switch away
* because the ->io_bitmap_max value must match the bitmap
* contents:
*/
- tss = &per_cpu(init_tss, get_cpu());
+ preempt_disable();
set_bitmap(t->io_bitmap_ptr, from, num, !turn_on);
@@ -85,10 +104,9 @@ asmlinkage long sys_ioperm(unsigned long from, unsigned long
num, int turn_on)
t->io_bitmap_max = bytes;
- /* Update the TSS: */
- memcpy(tss->io_bitmap, t->io_bitmap_ptr, bytes_updated);
+ set_io_bitmap(t, changed, bytes_updated);
- put_cpu();
+ preempt_enable();
return 0;
}
diff --git a/arch/x86/kernel/paravirt.c b/arch/x86/kernel/paravirt.c
index aa34423..1c15178 100644
--- a/arch/x86/kernel/paravirt.c
+++ b/arch/x86/kernel/paravirt.c
@@ -398,6 +398,7 @@ struct pv_cpu_ops pv_cpu_ops = {
.swapgs = native_swapgs,
.set_iopl_mask = native_set_iopl_mask,
+ .set_io_bitmap = native_set_io_bitmap,
.io_delay = native_io_delay,
.start_context_switch = paravirt_nop,
diff --git a/arch/x86/kernel/process.c b/arch/x86/kernel/process.c
index ac25491..174ab04 100644
--- a/arch/x86/kernel/process.c
+++ b/arch/x86/kernel/process.c
@@ -71,16 +71,12 @@ void exit_thread(void)
unsigned long *bp = t->io_bitmap_ptr;
if (bp) {
- struct tss_struct *tss = &per_cpu(init_tss, get_cpu());
-
+ preempt_disable();
t->io_bitmap_ptr = NULL;
clear_thread_flag(TIF_IO_BITMAP);
- /*
- * Careful, clear this in the TSS too:
- */
- memset(tss->io_bitmap, 0xff, t->io_bitmap_max);
+ set_io_bitmap(t, 1, t->io_bitmap_max);
t->io_bitmap_max = 0;
- put_cpu();
+ preempt_enable();
kfree(bp);
}
@@ -211,19 +207,10 @@ void __switch_to_xtra(struct task_struct *prev_p, struct
task_struct *next_p,
hard_enable_TSC();
}
- if (test_tsk_thread_flag(next_p, TIF_IO_BITMAP)) {
- /*
- * Copy the relevant range of the IO bitmap.
- * Normally this is 128 bytes or less:
- */
- memcpy(tss->io_bitmap, next->io_bitmap_ptr,
- max(prev->io_bitmap_max, next->io_bitmap_max));
- } else if (test_tsk_thread_flag(prev_p, TIF_IO_BITMAP)) {
- /*
- * Clear any possible leftover bits:
- */
- memset(tss->io_bitmap, 0xff, prev->io_bitmap_max);
- }
+ if (test_tsk_thread_flag(next_p, TIF_IO_BITMAP) ||
+ test_tsk_thread_flag(prev_p, TIF_IO_BITMAP))
+ set_io_bitmap(next, 1,
+ max(prev->io_bitmap_max, next->io_bitmap_max));
}
int sys_fork(struct pt_regs *regs)
diff --git a/arch/x86/xen/enlighten.c b/arch/x86/xen/enlighten.c
index 213e1ba..61ce3ae 100644
--- a/arch/x86/xen/enlighten.c
+++ b/arch/x86/xen/enlighten.c
@@ -568,6 +568,21 @@ static void xen_set_iopl_mask(unsigned mask)
HYPERVISOR_physdev_op(PHYSDEVOP_set_iopl, &set_iopl);
}
+static void xen_set_io_bitmap(struct thread_struct *thread,
+ int changed, unsigned long bytes_updated)
+{
+ struct physdev_set_iobitmap set_iobitmap;
+
+ if (!changed)
+ return;
+
+ set_xen_guest_handle(set_iobitmap.bitmap,
+ (char *)thread->io_bitmap_ptr);
+ set_iobitmap.nr_ports = thread->io_bitmap_ptr ? IO_BITMAP_BITS : 0;
+ WARN_ON(HYPERVISOR_physdev_op(PHYSDEVOP_set_iobitmap,
+ &set_iobitmap));
+}
+
static void xen_io_delay(void)
{
}
@@ -861,6 +876,7 @@ static const struct pv_cpu_ops xen_cpu_ops __initdata = {
.load_sp0 = xen_load_sp0,
.set_iopl_mask = xen_set_iopl_mask,
+ .set_io_bitmap = xen_set_io_bitmap,
.io_delay = xen_io_delay,
/* Xen takes care of %gs when switching to usermode for us */
--
1.6.0.6
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