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Olaf Hering

2011-Jul-15 15:38 UTC

[Xen-devel] [PATCH 0 of 4] xentrace fixes for xen-unstable

A few small changes and a new trace hypercall.

The hypercall patch is here for review, I''m open to suggestions for
better
naming for example.

I''m leaving the existing HVMOP_xentrace in place to not break the API,
even
if there are no users in the tree.

Olaf

 tools/libxc/xc_tbuf.c       |   46 ++++++++++++++++++++++++++++++++++++++++++++
 tools/libxc/xenctrl.h       |    2 +
 xen/arch/x86/hvm/hvm.c      |    3 --
 xen/arch/x86/irq.c          |   12 +++++++----
 xen/arch/x86/trace.c        |    3 ++
 xen/arch/x86/x86_32/entry.S |    2 +
 xen/arch/x86/x86_64/entry.S |    2 +
 xen/common/trace.c          |   21 +++++++++++++++++++-
 xen/include/public/trace.h  |   10 +++++++++
 xen/include/public/xen.h    |    1 
 xen/include/xen/hypercall.h |    5 ++++
 11 files changed, 100 insertions(+), 7 deletions(-)


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Olaf Hering

2011-Jul-15 15:38 UTC

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[Xen-devel] [PATCH 1 of 4] hvm: remove cast from trace_var call for HVMOP_xentrace

# HG changeset patch
# User Olaf Hering <olaf@aepfle.de>
# Date 1310741122 -7200
# Node ID d0dcdddf5285eba0605a95dfda79b794803fa733
# Parent  fbb448cf5cba5f441ad94f7783a0a1394fd638f9
hvm: remove cast from trace_var call for HVMOP_xentrace

trace_var() takes a void pointer, casting is not needed.

Signed-off-by: Olaf Hering <olaf@aepfle.de>

diff -r fbb448cf5cba -r d0dcdddf5285 xen/arch/x86/hvm/hvm.c
--- a/xen/arch/x86/hvm/hvm.c
+++ b/xen/arch/x86/hvm/hvm.c
@@ -3926,8 +3926,7 @@ long do_hvm_op(unsigned long op, XEN_GUE
 
         /* Cycles will be taken at the vmexit and vmenter */
         trace_var(tr.event | TRC_GUEST, 0 /*!cycles*/,
-                  tr.extra_bytes,
-                  (unsigned char *)tr.extra);
+                  tr.extra_bytes, tr.extra);
         break;
     }
 

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Olaf Hering

2011-Jul-15 15:38 UTC

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[Xen-devel] [PATCH 2 of 4] xentrace: replace ASSERT with printk in __trace_var

# HG changeset patch
# User Olaf Hering <olaf@aepfle.de>
# Date 1310741871 -7200
# Node ID e0ff4eea0432e0af3210e090a47414a0126e9904
# Parent  d0dcdddf5285eba0605a95dfda79b794803fa733
xentrace: replace ASSERT with printk in __trace_var

If trace_var gets called with large extra_data, do not crash the hypervisor.
Instead print a warning and truncate the buffer.

Signed-off-by: Olaf Hering <olaf@aepfle.de>

diff -r d0dcdddf5285 -r e0ff4eea0432 xen/common/trace.c
--- a/xen/common/trace.c
+++ b/xen/common/trace.c
@@ -683,7 +683,10 @@ void __trace_var(u32 event, bool_t cycle
     if ( (extra % sizeof(u32)) != 0 )
         extra_word++;
     
-    ASSERT(extra_word <= TRACE_EXTRA_MAX);
+    if ( unlikely(extra_word > TRACE_EXTRA_MAX) )
+        printk(XENLOG_WARNING "xentrace: event %x extra_data %u too
large.\n",
+                event, extra);
+
     extra_word = min_t(int, extra_word, TRACE_EXTRA_MAX);
 
     /* Round size up to nearest word */

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Olaf Hering

2011-Jul-15 15:38 UTC

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[Xen-devel] [PATCH 3 of 4] xentrace: reduce size of extradata in trace_irq_mask()

# HG changeset patch
# User Olaf Hering <olaf@aepfle.de>
# Date 1310743144 -7200
# Node ID 6e4aef7b5051e18f19f2367a4439bba8f495335c
# Parent  e0ff4eea0432e0af3210e090a47414a0126e9904
xentrace: reduce size of extradata in trace_irq_mask()

Reduce size of extra_data in to avoid possible crash in trace_var.

(XEN) Assertion ''extra_word <= TRACE_EXTRA_MAX'' failed at
trace.c:687
(XEN) Xen call trace:
(XEN)    [<ffff82c480128783>] __trace_var+0x4d/0x3b8
(XEN)    [<ffff82c480162172>] trace_irq_mask+0x49/0x4b
(XEN)    [<ffff82c4801631ae>] __assign_irq_vector+0x241/0x374
(XEN)    [<ffff82c48015d813>] set_desc_affinity+0x5d/0xd4
(XEN)    [<ffff82c480160708>] set_msi_affinity+0x44/0x1c1
(XEN)    [<ffff82c480162938>] move_masked_irq+0x9c/0xcd
(XEN)    [<ffff82c4801629a7>] move_native_irq+0x3e/0x53
(XEN)    [<ffff82c48015d969>] ack_msi_irq+0x2c/0x6e
(XEN)    [<ffff82c4801622e3>] do_IRQ+0x16f/0x66d

Signed-off-by: Olaf Hering <olaf@aepfle.de>

diff -r e0ff4eea0432 -r 6e4aef7b5051 xen/arch/x86/irq.c
--- a/xen/arch/x86/irq.c
+++ b/xen/arch/x86/irq.c
@@ -77,10 +77,14 @@ void unlock_vector_lock(void)
 static void trace_irq_mask(u32 event, int irq, int vector, cpumask_t *mask)
 {
     struct {
-        int irq, vec;
-        cpumask_t mask;
-    } d = { irq, vector, *mask };
-    trace_var(event, 1, sizeof(d), (unsigned char *)&d);
+        unsigned int irq:16, vec:16;
+        unsigned int mask[6];
+    } d;
+    d.irq = irq;
+    d.vec = vector;
+    memset(d.mask, 0, sizeof(d.mask));
+    memcpy(d.mask, mask, min(sizeof(d.mask), sizeof(cpumask_t)));
+    trace_var(event, 1, sizeof(d), &d);
 }
 
 static int __init __bind_irq_vector(int irq, int vector, cpumask_t cpu_mask)

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Olaf Hering

2011-Jul-15 15:38 UTC

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[Xen-devel] [PATCH 4 of 4] Add a trace hypercall to allow tracing from dom0 or domU

# HG changeset patch
# User Olaf Hering <olaf@aepfle.de>
# Date 1310744207 -7200
# Node ID f72dcd1b8bbdc7487d58702058983a5aa812a74e
# Parent  6e4aef7b5051e18f19f2367a4439bba8f495335c
Add a trace hypercall to allow tracing from dom0 or domU.

Mixing tracedata from Xen and dom0/domU events will help with debugging some
issues. Either the chain of events is nice to know, or there is no console
output available.

Signed-off-by: Olaf Hering <olaf@aepfle.de>

diff -r 6e4aef7b5051 -r f72dcd1b8bbd tools/libxc/xc_tbuf.c
--- a/tools/libxc/xc_tbuf.c
+++ b/tools/libxc/xc_tbuf.c
@@ -156,3 +156,49 @@ int xc_tbuf_set_evt_mask(xc_interface *x
     return do_sysctl(xch, &sysctl);
 }
 
+static void do_tbuf_trace(xc_interface *xch, xen_guest_xentrace_t *t_guest)
+{
+    DECLARE_HYPERCALL;
+    DECLARE_HYPERCALL_BOUNCE(t_guest, sizeof(*t_guest),
XC_HYPERCALL_BUFFER_BOUNCE_IN);
+
+    if ( xc_hypercall_bounce_pre(xch, t_guest) )
+    {
+        PERROR("Could not bounce buffer for xentrace hypercall");
+        return;
+    }
+
+    hypercall.op     = __HYPERVISOR_xentrace_op;
+    hypercall.arg[0] = HYPERCALL_BUFFER_AS_ARG(t_guest);
+    if ( do_xen_hypercall(xch, &hypercall) < 0 )
+    {
+        if ( errno == EACCES )
+            DPRINTF("sysctl operation failed -- need to"
+                    " rebuild the user-space tool set?\n");
+    }
+    xc_hypercall_bounce_post(xch, t_guest);
+}
+
+void xc_tbuf_trace(xc_interface *xch, uint16_t event, void *extra, size_t
extra_bytes)
+{
+    DECLARE_HYPERCALL_BUFFER(xen_guest_xentrace_t, t_guest);
+
+    t_guest = xc_hypercall_buffer_alloc(xch, t_guest,
sizeof(xen_guest_xentrace_t));
+    if ( !t_guest )
+    {
+        PERROR("Could not allocate memory for xentrace hypercall");
+        return ;
+    }
+
+    t_guest->event = event;
+    if ( extra_bytes )
+    {
+        if ( extra_bytes > sizeof(t_guest->extra) )
+            extra_bytes = sizeof(t_guest->extra);
+        memcpy(t_guest->extra, extra, extra_bytes);
+    }
+    t_guest->extra_bytes = extra_bytes;
+
+    do_tbuf_trace(xch, t_guest);
+
+    xc_hypercall_buffer_free(xch, t_guest);
+}
diff -r 6e4aef7b5051 -r f72dcd1b8bbd tools/libxc/xenctrl.h
--- a/tools/libxc/xenctrl.h
+++ b/tools/libxc/xenctrl.h
@@ -1269,6 +1269,8 @@ int xc_tbuf_set_cpu_mask(xc_interface *x
 
 int xc_tbuf_set_evt_mask(xc_interface *xch, uint32_t mask);
 
+void xc_tbuf_trace(xc_interface *xch, uint16_t event, void *extra, size_t
extra_bytes);
+
 int xc_domctl(xc_interface *xch, struct xen_domctl *domctl);
 int xc_sysctl(xc_interface *xch, struct xen_sysctl *sysctl);
 
diff -r 6e4aef7b5051 -r f72dcd1b8bbd xen/arch/x86/trace.c
--- a/xen/arch/x86/trace.c
+++ b/xen/arch/x86/trace.c
@@ -15,6 +15,9 @@ asmlinkage void trace_hypercall(void)
 {
     struct cpu_user_regs *regs = guest_cpu_user_regs();
 
+    if ( regs->eax == __HYPERVISOR_xentrace_op )
+        return;
+
 #ifdef __x86_64__
     if ( is_pv_32on64_vcpu(current) )
     {
diff -r 6e4aef7b5051 -r f72dcd1b8bbd xen/arch/x86/x86_32/entry.S
--- a/xen/arch/x86/x86_32/entry.S
+++ b/xen/arch/x86/x86_32/entry.S
@@ -699,6 +699,7 @@ ENTRY(hypercall_table)
         .long do_domctl
         .long do_kexec_op
         .long do_tmem_op
+        .long do_xentrace_op
         .rept __HYPERVISOR_arch_0-((.-hypercall_table)/4)
         .long do_ni_hypercall
         .endr
@@ -747,6 +748,7 @@ ENTRY(hypercall_args_table)
         .byte 1 /* do_domctl            */
         .byte 2 /* do_kexec_op          */
         .byte 1 /* do_tmem_op           */
+        .byte 0 /* do_xentrace_op       */
         .rept __HYPERVISOR_arch_0-(.-hypercall_args_table)
         .byte 0 /* do_ni_hypercall      */
         .endr
diff -r 6e4aef7b5051 -r f72dcd1b8bbd xen/arch/x86/x86_64/entry.S
--- a/xen/arch/x86/x86_64/entry.S
+++ b/xen/arch/x86/x86_64/entry.S
@@ -694,6 +694,7 @@ ENTRY(hypercall_table)
         .quad do_domctl
         .quad do_kexec_op
         .quad do_tmem_op
+        .quad do_xentrace_op
         .rept __HYPERVISOR_arch_0-((.-hypercall_table)/8)
         .quad do_ni_hypercall
         .endr
@@ -742,6 +743,7 @@ ENTRY(hypercall_args_table)
         .byte 1 /* do_domctl            */
         .byte 2 /* do_kexec             */
         .byte 1 /* do_tmem_op           */
+        .byte 0 /* do_xentrace_op       */
         .rept __HYPERVISOR_arch_0-(.-hypercall_args_table)
         .byte 0 /* do_ni_hypercall      */
         .endr
diff -r 6e4aef7b5051 -r f72dcd1b8bbd xen/common/trace.c
--- a/xen/common/trace.c
+++ b/xen/common/trace.c
@@ -31,6 +31,7 @@
 #include <xen/percpu.h>
 #include <xen/pfn.h>
 #include <xen/cpu.h>
+#include <xen/guest_access.h>
 #include <asm/atomic.h>
 #include <public/sysctl.h>
 
@@ -806,6 +807,21 @@ unlock:
         tasklet_schedule(&trace_notify_dom0_tasklet);
 }
 
+void do_xentrace_op(XEN_GUEST_HANDLE(xen_guest_xentrace_t) u_xentrace)
+{
+    xen_guest_xentrace_t tr;
+
+    if ( copy_from_guest(&tr, u_xentrace, 1 ) )
+        return;
+    if ( tr.event & ~((1u<<TRC_SUBCLS_SHIFT)-1) )
+        return;
+
+    if ( tr.extra_bytes > sizeof(tr.extra) )
+        tr.extra_bytes = sizeof(tr.extra);
+
+    __trace_var(tr.event | TRC_GUEST, 1, tr.extra_bytes, tr.extra);
+}
+
 /*
  * Local variables:
  * mode: C
diff -r 6e4aef7b5051 -r f72dcd1b8bbd xen/include/public/trace.h
--- a/xen/include/public/trace.h
+++ b/xen/include/public/trace.h
@@ -26,6 +26,8 @@
 #ifndef __XEN_PUBLIC_TRACE_H__
 #define __XEN_PUBLIC_TRACE_H__
 
+#include "xen.h"
+
 #define TRACE_EXTRA_MAX    7
 #define TRACE_EXTRA_SHIFT 28
 
@@ -65,6 +67,7 @@
 #define TRC_LOST_RECORDS        (TRC_GEN + 1)
 #define TRC_TRACE_WRAP_BUFFER  (TRC_GEN + 2)
 #define TRC_TRACE_CPU_CHANGE    (TRC_GEN + 3)
+#define TRC_TRACE_GUEST_HYPERCALL (TRC_GEN + 4)
 
 #define TRC_SCHED_RUNSTATE_CHANGE   (TRC_SCHED_MIN + 1)
 #define TRC_SCHED_CONTINUE_RUNNING  (TRC_SCHED_MIN + 2)
@@ -200,6 +203,13 @@ struct t_rec {
     } u;
 };
 
+struct xen_guest_xentrace {
+    uint16_t event, extra_bytes;
+    uint8_t extra[TRACE_EXTRA_MAX * sizeof(uint32_t)];
+};
+typedef struct xen_guest_xentrace xen_guest_xentrace_t;
+DEFINE_XEN_GUEST_HANDLE(xen_guest_xentrace_t);
+
 /*
  * This structure contains the metadata for a single trace buffer.  The head
  * field, indexes into an array of struct t_rec''s.
diff -r 6e4aef7b5051 -r f72dcd1b8bbd xen/include/public/xen.h
--- a/xen/include/public/xen.h
+++ b/xen/include/public/xen.h
@@ -94,6 +94,7 @@ DEFINE_XEN_GUEST_HANDLE(xen_pfn_t);
 #define __HYPERVISOR_kexec_op             37
 #define __HYPERVISOR_tmem_op              38
 #define __HYPERVISOR_xc_reserved_op       39 /* reserved for XenClient */
+#define __HYPERVISOR_xentrace_op          40
 
 /* Architecture-specific hypercall definitions. */
 #define __HYPERVISOR_arch_0               48
diff -r 6e4aef7b5051 -r f72dcd1b8bbd xen/include/xen/hypercall.h
--- a/xen/include/xen/hypercall.h
+++ b/xen/include/xen/hypercall.h
@@ -14,6 +14,7 @@
 #include <public/platform.h>
 #include <public/event_channel.h>
 #include <public/tmem.h>
+#include <public/trace.h>
 #include <asm/hypercall.h>
 #include <xsm/xsm.h>
 
@@ -43,6 +44,10 @@ extern long
 do_platform_op(
     XEN_GUEST_HANDLE(xen_platform_op_t) u_xenpf_op);
 
+extern void
+do_xentrace_op(
+    XEN_GUEST_HANDLE(xen_guest_xentrace_t) u_xentrace);
+
 /*
  * To allow safe resume of do_memory_op() after preemption, we need to know
  * at what point in the page list to resume. For this purpose I steal the

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George Dunlap

2011-Jul-15 15:48 UTC

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[Xen-devel] Re: [PATCH 1 of 4] hvm: remove cast from trace_var call for HVMOP_xentrace

Acked-by: George Dunlap <george.dunlap@eu.citrix.com>

On Fri, 2011-07-15 at 16:38 +0100, Olaf Hering wrote:> # HG changeset patch
> # User Olaf Hering <olaf@aepfle.de>
> # Date 1310741122 -7200
> # Node ID d0dcdddf5285eba0605a95dfda79b794803fa733
> # Parent  fbb448cf5cba5f441ad94f7783a0a1394fd638f9
> hvm: remove cast from trace_var call for HVMOP_xentrace
> 
> trace_var() takes a void pointer, casting is not needed.
> 
> Signed-off-by: Olaf Hering <olaf@aepfle.de>
> 
> diff -r fbb448cf5cba -r d0dcdddf5285 xen/arch/x86/hvm/hvm.c
> --- a/xen/arch/x86/hvm/hvm.c
> +++ b/xen/arch/x86/hvm/hvm.c
> @@ -3926,8 +3926,7 @@ long do_hvm_op(unsigned long op, XEN_GUE
>  
>          /* Cycles will be taken at the vmexit and vmenter */
>          trace_var(tr.event | TRC_GUEST, 0 /*!cycles*/,
> -                  tr.extra_bytes,
> -                  (unsigned char *)tr.extra);
> +                  tr.extra_bytes, tr.extra);
>          break;
>      }
>  


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George Dunlap

2011-Jul-15 16:28 UTC

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[Xen-devel] Re: [PATCH 3 of 4] xentrace: reduce size of extradata in trace_irq_mask()

Acked-by: George Dunlap <george.dunlap@eu.citrix.com>

On Fri, 2011-07-15 at 16:38 +0100, Olaf Hering wrote:> # HG changeset patch
> # User Olaf Hering <olaf@aepfle.de>
> # Date 1310743144 -7200
> # Node ID 6e4aef7b5051e18f19f2367a4439bba8f495335c
> # Parent  e0ff4eea0432e0af3210e090a47414a0126e9904
> xentrace: reduce size of extradata in trace_irq_mask()
> 
> Reduce size of extra_data in to avoid possible crash in trace_var.
> 
> (XEN) Assertion ''extra_word <= TRACE_EXTRA_MAX'' failed
at trace.c:687
> (XEN) Xen call trace:
> (XEN)    [<ffff82c480128783>] __trace_var+0x4d/0x3b8
> (XEN)    [<ffff82c480162172>] trace_irq_mask+0x49/0x4b
> (XEN)    [<ffff82c4801631ae>] __assign_irq_vector+0x241/0x374
> (XEN)    [<ffff82c48015d813>] set_desc_affinity+0x5d/0xd4
> (XEN)    [<ffff82c480160708>] set_msi_affinity+0x44/0x1c1
> (XEN)    [<ffff82c480162938>] move_masked_irq+0x9c/0xcd
> (XEN)    [<ffff82c4801629a7>] move_native_irq+0x3e/0x53
> (XEN)    [<ffff82c48015d969>] ack_msi_irq+0x2c/0x6e
> (XEN)    [<ffff82c4801622e3>] do_IRQ+0x16f/0x66d
> 
> Signed-off-by: Olaf Hering <olaf@aepfle.de>
> 
> diff -r e0ff4eea0432 -r 6e4aef7b5051 xen/arch/x86/irq.c
> --- a/xen/arch/x86/irq.c
> +++ b/xen/arch/x86/irq.c
> @@ -77,10 +77,14 @@ void unlock_vector_lock(void)
>  static void trace_irq_mask(u32 event, int irq, int vector, cpumask_t
*mask)
>  {
>      struct {
> -        int irq, vec;
> -        cpumask_t mask;
> -    } d = { irq, vector, *mask };
> -    trace_var(event, 1, sizeof(d), (unsigned char *)&d);
> +        unsigned int irq:16, vec:16;
> +        unsigned int mask[6];
> +    } d;
> +    d.irq = irq;
> +    d.vec = vector;
> +    memset(d.mask, 0, sizeof(d.mask));
> +    memcpy(d.mask, mask, min(sizeof(d.mask), sizeof(cpumask_t)));
> +    trace_var(event, 1, sizeof(d), &d);
>  }
>  
>  static int __init __bind_irq_vector(int irq, int vector, cpumask_t
cpu_mask)


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George Dunlap

2011-Jul-15 16:31 UTC

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[Xen-devel] Re: [PATCH 2 of 4] xentrace: replace ASSERT with printk in __trace_var

This seems likely to spam the console if there is a trace which violates
this; and this may happen in production environments if the loglevel is
increased.  I think putting in something to warn just once would be a
better idea.

 -George

On Fri, 2011-07-15 at 16:38 +0100, Olaf Hering wrote:> # HG changeset patch
> # User Olaf Hering <olaf@aepfle.de>
> # Date 1310741871 -7200
> # Node ID e0ff4eea0432e0af3210e090a47414a0126e9904
> # Parent  d0dcdddf5285eba0605a95dfda79b794803fa733
> xentrace: replace ASSERT with printk in __trace_var
> 
> If trace_var gets called with large extra_data, do not crash the
hypervisor.
> Instead print a warning and truncate the buffer.
> 
> Signed-off-by: Olaf Hering <olaf@aepfle.de>
> 
> diff -r d0dcdddf5285 -r e0ff4eea0432 xen/common/trace.c
> --- a/xen/common/trace.c
> +++ b/xen/common/trace.c
> @@ -683,7 +683,10 @@ void __trace_var(u32 event, bool_t cycle
>      if ( (extra % sizeof(u32)) != 0 )
>          extra_word++;
>      
> -    ASSERT(extra_word <= TRACE_EXTRA_MAX);
> +    if ( unlikely(extra_word > TRACE_EXTRA_MAX) )
> +        printk(XENLOG_WARNING "xentrace: event %x extra_data %u too
large.\n",
> +                event, extra);
> +
>      extra_word = min_t(int, extra_word, TRACE_EXTRA_MAX);
>  
>      /* Round size up to nearest word */


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George Dunlap

2011-Jul-15 16:49 UTC

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[Xen-devel] Re: [PATCH 4 of 4] Add a trace hypercall to allow tracing from dom0 or domU

On Fri, 2011-07-15 at 16:38 +0100, Olaf Hering wrote:> diff -r 6e4aef7b5051 -r f72dcd1b8bbd xen/include/public/trace.h
> --- a/xen/include/public/trace.h
> +++ b/xen/include/public/trace.h
> @@ -26,6 +26,8 @@
>  #ifndef __XEN_PUBLIC_TRACE_H__
>  #define __XEN_PUBLIC_TRACE_H__
>  
> +#include "xen.h"
> +
>  #define TRACE_EXTRA_MAX    7
>  #define TRACE_EXTRA_SHIFT 28
>  
> @@ -65,6 +67,7 @@
>  #define TRC_LOST_RECORDS        (TRC_GEN + 1)
>  #define TRC_TRACE_WRAP_BUFFER  (TRC_GEN + 2)
>  #define TRC_TRACE_CPU_CHANGE    (TRC_GEN + 3)
> +#define TRC_TRACE_GUEST_HYPERCALL (TRC_GEN + 4)
Looks like perhaps a leftover from an earlier patch? :-)
> diff -r 6e4aef7b5051 -r f72dcd1b8bbd xen/include/public/xen.h
> --- a/xen/include/public/xen.h
> +++ b/xen/include/public/xen.h
> @@ -94,6 +94,7 @@ DEFINE_XEN_GUEST_HANDLE(xen_pfn_t);
>  #define __HYPERVISOR_kexec_op             37
>  #define __HYPERVISOR_tmem_op              38
>  #define __HYPERVISOR_xc_reserved_op       39 /* reserved for XenClient */
> +#define __HYPERVISOR_xentrace_op          40
Seems unnecessary to make a whole hypercall just for this one thing, but
I''ll defer to Keir''s judgement on that.  At very least, it
should accept
an "op" command, of which "trace" is just one, so that
it''s expandable
in the future without breaking backwards compatibility.

Other than that, looks good -- thanks for doing this.

 -George


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Olaf Hering

2011-Jul-15 20:45 UTC

head link

[Xen-devel] Re: [PATCH 4 of 4] Add a trace hypercall to allow tracing from dom0 or domU

On Fri, Jul 15, George Dunlap wrote:
> On Fri, 2011-07-15 at 16:38 +0100, Olaf Hering wrote:
> > @@ -65,6 +67,7 @@
> >  #define TRC_LOST_RECORDS        (TRC_GEN + 1)
> >  #define TRC_TRACE_WRAP_BUFFER  (TRC_GEN + 2)
> >  #define TRC_TRACE_CPU_CHANGE    (TRC_GEN + 3)
> > +#define TRC_TRACE_GUEST_HYPERCALL (TRC_GEN + 4)
> 
> Looks like perhaps a leftover from an earlier patch? :-)
Yes, thats true. It was a domctrl a few weeks ago.
> > diff -r 6e4aef7b5051 -r f72dcd1b8bbd xen/include/public/xen.h
> > --- a/xen/include/public/xen.h
> > +++ b/xen/include/public/xen.h
> > @@ -94,6 +94,7 @@ DEFINE_XEN_GUEST_HANDLE(xen_pfn_t);
> >  #define __HYPERVISOR_kexec_op             37
> >  #define __HYPERVISOR_tmem_op              38
> >  #define __HYPERVISOR_xc_reserved_op       39 /* reserved for
XenClient */
> > +#define __HYPERVISOR_xentrace_op          40
> 
> Seems unnecessary to make a whole hypercall just for this one thing, but
> I''ll defer to Keir''s judgement on that.  At very least,
it should accept
> an "op" command, of which "trace" is just one, so that
it''s expandable
> in the future without breaking backwards compatibility.
One reason is that trace_hypercall() should not trace itself.

Olaf

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Keir Fraser

2011-Jul-16 08:20 UTC

head link

Re: [Xen-devel] Re: [PATCH 2 of 4] xentrace: replace ASSERT with printk in __trace_var

It''s not like we have dodgy third-party drivers to worry about. Just
fix the
code -- *which is in the tree!* -- that is making the bad calls! It was
correct to make this an assert/bug_on in the first place.

 -- Keir

On 15/07/2011 17:31, "George Dunlap" <george.dunlap@citrix.com>
wrote:
> This seems likely to spam the console if there is a trace which violates
> this; and this may happen in production environments if the loglevel is
> increased.  I think putting in something to warn just once would be a
> better idea.
> 
>  -George
> 
> On Fri, 2011-07-15 at 16:38 +0100, Olaf Hering wrote:
>> # HG changeset patch
>> # User Olaf Hering <olaf@aepfle.de>
>> # Date 1310741871 -7200
>> # Node ID e0ff4eea0432e0af3210e090a47414a0126e9904
>> # Parent  d0dcdddf5285eba0605a95dfda79b794803fa733
>> xentrace: replace ASSERT with printk in __trace_var
>> 
>> If trace_var gets called with large extra_data, do not crash the
hypervisor.
>> Instead print a warning and truncate the buffer.
>> 
>> Signed-off-by: Olaf Hering <olaf@aepfle.de>
>> 
>> diff -r d0dcdddf5285 -r e0ff4eea0432 xen/common/trace.c
>> --- a/xen/common/trace.c
>> +++ b/xen/common/trace.c
>> @@ -683,7 +683,10 @@ void __trace_var(u32 event, bool_t cycle
>>      if ( (extra % sizeof(u32)) != 0 )
>>          extra_word++;
>>      
>> -    ASSERT(extra_word <= TRACE_EXTRA_MAX);
>> +    if ( unlikely(extra_word > TRACE_EXTRA_MAX) )
>> +        printk(XENLOG_WARNING "xentrace: event %x extra_data %u
too
>> large.\n",
>> +                event, extra);
>> +
>>      extra_word = min_t(int, extra_word, TRACE_EXTRA_MAX);
>>  
>>      /* Round size up to nearest word */
> 
> 
> 
> _______________________________________________
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> Xen-devel@lists.xensource.com
> http://lists.xensource.com/xen-devel


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Keir Fraser

2011-Jul-16 08:25 UTC

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Re: [Xen-devel] [PATCH 3 of 4] xentrace: reduce size of extradata in trace_irq_mask()

On 15/07/2011 16:38, "Olaf Hering" <olaf@aepfle.de> wrote:
> # HG changeset patch
> # User Olaf Hering <olaf@aepfle.de>
> # Date 1310743144 -7200
> # Node ID 6e4aef7b5051e18f19f2367a4439bba8f495335c
> # Parent  e0ff4eea0432e0af3210e090a47414a0126e9904
> xentrace: reduce size of extradata in trace_irq_mask()
> 
> Reduce size of extra_data in to avoid possible crash in trace_var.
Ah, so the assertion did its job. :-)

 -- Keir
> (XEN) Assertion ''extra_word <= TRACE_EXTRA_MAX'' failed
at trace.c:687
> (XEN) Xen call trace:
> (XEN)    [<ffff82c480128783>] __trace_var+0x4d/0x3b8
> (XEN)    [<ffff82c480162172>] trace_irq_mask+0x49/0x4b
> (XEN)    [<ffff82c4801631ae>] __assign_irq_vector+0x241/0x374
> (XEN)    [<ffff82c48015d813>] set_desc_affinity+0x5d/0xd4
> (XEN)    [<ffff82c480160708>] set_msi_affinity+0x44/0x1c1
> (XEN)    [<ffff82c480162938>] move_masked_irq+0x9c/0xcd
> (XEN)    [<ffff82c4801629a7>] move_native_irq+0x3e/0x53
> (XEN)    [<ffff82c48015d969>] ack_msi_irq+0x2c/0x6e
> (XEN)    [<ffff82c4801622e3>] do_IRQ+0x16f/0x66d
> 
> Signed-off-by: Olaf Hering <olaf@aepfle.de>
> 
> diff -r e0ff4eea0432 -r 6e4aef7b5051 xen/arch/x86/irq.c
> --- a/xen/arch/x86/irq.c
> +++ b/xen/arch/x86/irq.c
> @@ -77,10 +77,14 @@ void unlock_vector_lock(void)
>  static void trace_irq_mask(u32 event, int irq, int vector, cpumask_t
*mask)
>  {
>      struct {
> -        int irq, vec;
> -        cpumask_t mask;
> -    } d = { irq, vector, *mask };
> -    trace_var(event, 1, sizeof(d), (unsigned char *)&d);
> +        unsigned int irq:16, vec:16;
> +        unsigned int mask[6];
> +    } d;
> +    d.irq = irq;
> +    d.vec = vector;
> +    memset(d.mask, 0, sizeof(d.mask));
> +    memcpy(d.mask, mask, min(sizeof(d.mask), sizeof(cpumask_t)));
> +    trace_var(event, 1, sizeof(d), &d);
>  }
>  
>  static int __init __bind_irq_vector(int irq, int vector, cpumask_t
cpu_mask)
> 
> _______________________________________________
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> Xen-devel@lists.xensource.com
> http://lists.xensource.com/xen-devel


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Tim Deegan

2011-Jul-18 08:56 UTC

head link

Re: [Xen-devel] [PATCH 4 of 4] Add a trace hypercall to allow tracing from dom0 or domU

Hi, 

At 17:38 +0200 on 15 Jul (1310751488), Olaf Hering
wrote:> diff -r 6e4aef7b5051 -r f72dcd1b8bbd xen/arch/x86/x86_32/entry.S
> --- a/xen/arch/x86/x86_32/entry.S
> +++ b/xen/arch/x86/x86_32/entry.S
> @@ -699,6 +699,7 @@ ENTRY(hypercall_table)
>          .long do_domctl
>          .long do_kexec_op
>          .long do_tmem_op
> +        .long do_xentrace_op
>          .rept __HYPERVISOR_arch_0-((.-hypercall_table)/4)
>          .long do_ni_hypercall
>          .endr
> @@ -747,6 +748,7 @@ ENTRY(hypercall_args_table)
>          .byte 1 /* do_domctl            */
>          .byte 2 /* do_kexec_op          */
>          .byte 1 /* do_tmem_op           */
> +        .byte 0 /* do_xentrace_op       */
>          .rept __HYPERVISOR_arch_0-(.-hypercall_args_table)
>          .byte 0 /* do_ni_hypercall      */
>          .endr
> diff -r 6e4aef7b5051 -r f72dcd1b8bbd xen/arch/x86/x86_64/entry.S
> --- a/xen/arch/x86/x86_64/entry.S
> +++ b/xen/arch/x86/x86_64/entry.S
> @@ -694,6 +694,7 @@ ENTRY(hypercall_table)
>          .quad do_domctl
>          .quad do_kexec_op
>          .quad do_tmem_op
> +        .quad do_xentrace_op
>          .rept __HYPERVISOR_arch_0-((.-hypercall_table)/8)
>          .quad do_ni_hypercall
>          .endr
> @@ -742,6 +743,7 @@ ENTRY(hypercall_args_table)
>          .byte 1 /* do_domctl            */
>          .byte 2 /* do_kexec             */
>          .byte 1 /* do_tmem_op           */
> +        .byte 0 /* do_xentrace_op       */
>          .rept __HYPERVISOR_arch_0-(.-hypercall_args_table)
>          .byte 0 /* do_ni_hypercall      */
>          .endr
You need to do the same in x86/x86_64/compat/entry.S for 32-on-64 guests
to be able to call it too.

Also, can you add some comments somewhere (say, public/trace.h) to say
exactly what the new hypercall does and how to use it?  A patch to
docs/src/interface.tex would be great too, even if the rest of that doc
is quite out of date. 

George, is it worth trying to merge this into the existing HVMOP that
does the same thing?

Cheers,

Tim.

-- 
Tim Deegan <Tim.Deegan@citrix.com>
Principal Software Engineer, Xen Platform Team
Citrix Systems UK Ltd.  (Company #02937203, SL9 0BG)

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Olaf Hering

2011-Jul-18 09:04 UTC

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Re: [Xen-devel] Re: [PATCH 2 of 4] xentrace: replace ASSERT with printk in __trace_var

On Sat, Jul 16, Keir Fraser wrote:
> It''s not like we have dodgy third-party drivers to worry about.
Just fix the
> code -- *which is in the tree!* -- that is making the bad calls! It was
> correct to make this an assert/bug_on in the first place.
trace_irq_mask() was the only function I found with a too large buffer.

Olaf

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Keir Fraser

2011-Jul-18 09:37 UTC

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Re: [Xen-devel] Re: [PATCH 2 of 4] xentrace: replace ASSERT with printk in __trace_var

On 18/07/2011 10:04, "Olaf Hering" <olaf@aepfle.de> wrote:
> On Sat, Jul 16, Keir Fraser wrote:
> 
>> It''s not like we have dodgy third-party drivers to worry
about. Just fix the
>> code -- *which is in the tree!* -- that is making the bad calls! It was
>> correct to make this an assert/bug_on in the first place.
> 
> trace_irq_mask() was the only function I found with a too large buffer.
Yes, the fix was the very next email I looked at. I''ve applied it.
Thanks!

 -- Keir
> Olaf


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George Dunlap

2011-Jul-18 10:41 UTC

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Re: [Xen-devel] Re: [PATCH 2 of 4] xentrace: replace ASSERT with printk in __trace_var

On Sat, 2011-07-16 at 09:20 +0100, Keir Fraser wrote:> It''s not like we have dodgy third-party drivers to worry about.
Just fix the
> code -- *which is in the tree!* -- that is making the bad calls! It was
> correct to make this an assert/bug_on in the first place.
I think Olaf was objecting to a relatively minor fault like this causing
a hypervisor crash (in debug builds only of course), and asked if it
could be changed to a warning instead.  

My personal preference would be to keep it an ASSERT, but I''m not
really
that fussed either way.  The main thing is to make sure that only debug
builds may have significant negative effects, and I think this patch
doesn''t satisfy that (as if you add loglvl=all on a production system,
you may get stuck sending significant output to the console).

 -George
> 
>  -- Keir
> 
> On 15/07/2011 17:31, "George Dunlap"
<george.dunlap@citrix.com> wrote:
> 
> > This seems likely to spam the console if there is a trace which
violates
> > this; and this may happen in production environments if the loglevel
is
> > increased.  I think putting in something to warn just once would be a
> > better idea.
> > 
> >  -George
> > 
> > On Fri, 2011-07-15 at 16:38 +0100, Olaf Hering wrote:
> >> # HG changeset patch
> >> # User Olaf Hering <olaf@aepfle.de>
> >> # Date 1310741871 -7200
> >> # Node ID e0ff4eea0432e0af3210e090a47414a0126e9904
> >> # Parent  d0dcdddf5285eba0605a95dfda79b794803fa733
> >> xentrace: replace ASSERT with printk in __trace_var
> >> 
> >> If trace_var gets called with large extra_data, do not crash the
hypervisor.
> >> Instead print a warning and truncate the buffer.
> >> 
> >> Signed-off-by: Olaf Hering <olaf@aepfle.de>
> >> 
> >> diff -r d0dcdddf5285 -r e0ff4eea0432 xen/common/trace.c
> >> --- a/xen/common/trace.c
> >> +++ b/xen/common/trace.c
> >> @@ -683,7 +683,10 @@ void __trace_var(u32 event, bool_t cycle
> >>      if ( (extra % sizeof(u32)) != 0 )
> >>          extra_word++;
> >>      
> >> -    ASSERT(extra_word <= TRACE_EXTRA_MAX);
> >> +    if ( unlikely(extra_word > TRACE_EXTRA_MAX) )
> >> +        printk(XENLOG_WARNING "xentrace: event %x extra_data
%u too
> >> large.\n",
> >> +                event, extra);
> >> +
> >>      extra_word = min_t(int, extra_word, TRACE_EXTRA_MAX);
> >>  
> >>      /* Round size up to nearest word */
> > 
> > 
> > 
> > _______________________________________________
> > Xen-devel mailing list
> > Xen-devel@lists.xensource.com
> > http://lists.xensource.com/xen-devel
> 
> 


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Keir Fraser

2011-Jul-18 11:12 UTC

head link

Re: [Xen-devel] Re: [PATCH 2 of 4] xentrace: replace ASSERT with printk in __trace_var

On 18/07/2011 11:41, "George Dunlap" <george.dunlap@citrix.com>
wrote:
> On Sat, 2011-07-16 at 09:20 +0100, Keir Fraser wrote:
>> It''s not like we have dodgy third-party drivers to worry
about. Just fix the
>> code -- *which is in the tree!* -- that is making the bad calls! It was
>> correct to make this an assert/bug_on in the first place.
> 
> I think Olaf was objecting to a relatively minor fault like this causing
> a hypervisor crash (in debug builds only of course), and asked if it
> could be changed to a warning instead.
> 
> My personal preference would be to keep it an ASSERT, but I''m not
really
> that fussed either way.  The main thing is to make sure that only debug
> builds may have significant negative effects, and I think this patch
> doesn''t satisfy that (as if you add loglvl=all on a production
system,
> you may get stuck sending significant output to the console).
It only has a negative effect if you have xentrace enabled. That''s
fine.

 -- Keir
>  -George
> 
>> 
>>  -- Keir
>> 
>> On 15/07/2011 17:31, "George Dunlap"
<george.dunlap@citrix.com> wrote:
>> 
>>> This seems likely to spam the console if there is a trace which
violates
>>> this; and this may happen in production environments if the
loglevel is
>>> increased.  I think putting in something to warn just once would be
a
>>> better idea.
>>> 
>>>  -George
>>> 
>>> On Fri, 2011-07-15 at 16:38 +0100, Olaf Hering wrote:
>>>> # HG changeset patch
>>>> # User Olaf Hering <olaf@aepfle.de>
>>>> # Date 1310741871 -7200
>>>> # Node ID e0ff4eea0432e0af3210e090a47414a0126e9904
>>>> # Parent  d0dcdddf5285eba0605a95dfda79b794803fa733
>>>> xentrace: replace ASSERT with printk in __trace_var
>>>> 
>>>> If trace_var gets called with large extra_data, do not crash
the
>>>> hypervisor.
>>>> Instead print a warning and truncate the buffer.
>>>> 
>>>> Signed-off-by: Olaf Hering <olaf@aepfle.de>
>>>> 
>>>> diff -r d0dcdddf5285 -r e0ff4eea0432 xen/common/trace.c
>>>> --- a/xen/common/trace.c
>>>> +++ b/xen/common/trace.c
>>>> @@ -683,7 +683,10 @@ void __trace_var(u32 event, bool_t cycle
>>>>      if ( (extra % sizeof(u32)) != 0 )
>>>>          extra_word++;
>>>>      
>>>> -    ASSERT(extra_word <= TRACE_EXTRA_MAX);
>>>> +    if ( unlikely(extra_word > TRACE_EXTRA_MAX) )
>>>> +        printk(XENLOG_WARNING "xentrace: event %x
extra_data %u too
>>>> large.\n",
>>>> +                event, extra);
>>>> +
>>>>      extra_word = min_t(int, extra_word, TRACE_EXTRA_MAX);
>>>>  
>>>>      /* Round size up to nearest word */
>>> 
>>> 
>>> 
>>> _______________________________________________
>>> Xen-devel mailing list
>>> Xen-devel@lists.xensource.com
>>> http://lists.xensource.com/xen-devel
>> 
>> 
> 
> 


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George Dunlap

2011-Jul-18 11:17 UTC

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Re: [Xen-devel] [PATCH 4 of 4] Add a trace hypercall to allow tracing from dom0 or domU

On Mon, 2011-07-18 at 09:56 +0100, Tim Deegan wrote:> Hi, 
> 
> At 17:38 +0200 on 15 Jul (1310751488), Olaf Hering wrote:
> > diff -r 6e4aef7b5051 -r f72dcd1b8bbd xen/arch/x86/x86_32/entry.S
> > --- a/xen/arch/x86/x86_32/entry.S
> > +++ b/xen/arch/x86/x86_32/entry.S
> > @@ -699,6 +699,7 @@ ENTRY(hypercall_table)
> >          .long do_domctl
> >          .long do_kexec_op
> >          .long do_tmem_op
> > +        .long do_xentrace_op
> >          .rept __HYPERVISOR_arch_0-((.-hypercall_table)/4)
> >          .long do_ni_hypercall
> >          .endr
> > @@ -747,6 +748,7 @@ ENTRY(hypercall_args_table)
> >          .byte 1 /* do_domctl            */
> >          .byte 2 /* do_kexec_op          */
> >          .byte 1 /* do_tmem_op           */
> > +        .byte 0 /* do_xentrace_op       */
> >          .rept __HYPERVISOR_arch_0-(.-hypercall_args_table)
> >          .byte 0 /* do_ni_hypercall      */
> >          .endr
> > diff -r 6e4aef7b5051 -r f72dcd1b8bbd xen/arch/x86/x86_64/entry.S
> > --- a/xen/arch/x86/x86_64/entry.S
> > +++ b/xen/arch/x86/x86_64/entry.S
> > @@ -694,6 +694,7 @@ ENTRY(hypercall_table)
> >          .quad do_domctl
> >          .quad do_kexec_op
> >          .quad do_tmem_op
> > +        .quad do_xentrace_op
> >          .rept __HYPERVISOR_arch_0-((.-hypercall_table)/8)
> >          .quad do_ni_hypercall
> >          .endr
> > @@ -742,6 +743,7 @@ ENTRY(hypercall_args_table)
> >          .byte 1 /* do_domctl            */
> >          .byte 2 /* do_kexec             */
> >          .byte 1 /* do_tmem_op           */
> > +        .byte 0 /* do_xentrace_op       */
> >          .rept __HYPERVISOR_arch_0-(.-hypercall_args_table)
> >          .byte 0 /* do_ni_hypercall      */
> >          .endr
> 
> You need to do the same in x86/x86_64/compat/entry.S for 32-on-64 guests
> to be able to call it too.
> 
> Also, can you add some comments somewhere (say, public/trace.h) to say
> exactly what the new hypercall does and how to use it?  A patch to
> docs/src/interface.tex would be great too, even if the rest of that doc
> is quite out of date. 
> 
> George, is it worth trying to merge this into the existing HVMOP that
> does the same thing?
I''m not sure what you mean by "merging this into the existing
HVMOP".
Do you mean just having dom0 (or whoever) call HVMOP_trace instead of
making a separate hypercall?

 -George



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Tim Deegan

2011-Jul-18 12:22 UTC

head link

Re: [Xen-devel] [PATCH 4 of 4] Add a trace hypercall to allow tracing from dom0 or domU

At 12:17 +0100 on 18 Jul (1310991456), George Dunlap
wrote:> > George, is it worth trying to merge this into the existing HVMOP that
> > does the same thing?
> 
> I''m not sure what you mean by "merging this into the existing
HVMOP".
> Do you mean just having dom0 (or whoever) call HVMOP_trace instead of
> making a separate hypercall?
No, I just meant sharing some code.  The new hypercall adds struct
xen_guest_xentrace, which is basically a dup of struct xen_hvm_xentrace,
and do_xentrace_op() looks very like the code in do_hvm_op().

Tim.

-- 
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Principal Software Engineer, Xen Platform Team
Citrix Systems UK Ltd.  (Company #02937203, SL9 0BG)

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Xen devel - Jul 2011 - [PATCH 0 of 4] xentrace fixes for xen-unstable

[Xen-devel] [PATCH 0 of 4] xentrace fixes for xen-unstable

[Xen-devel] [PATCH 1 of 4] hvm: remove cast from trace_var call for HVMOP_xentrace

[Xen-devel] [PATCH 2 of 4] xentrace: replace ASSERT with printk in __trace_var

[Xen-devel] [PATCH 3 of 4] xentrace: reduce size of extradata in trace_irq_mask()

[Xen-devel] [PATCH 4 of 4] Add a trace hypercall to allow tracing from dom0 or domU

[Xen-devel] Re: [PATCH 1 of 4] hvm: remove cast from trace_var call for HVMOP_xentrace

[Xen-devel] Re: [PATCH 3 of 4] xentrace: reduce size of extradata in trace_irq_mask()

[Xen-devel] Re: [PATCH 2 of 4] xentrace: replace ASSERT with printk in __trace_var

[Xen-devel] Re: [PATCH 4 of 4] Add a trace hypercall to allow tracing from dom0 or domU

[Xen-devel] Re: [PATCH 4 of 4] Add a trace hypercall to allow tracing from dom0 or domU

Re: [Xen-devel] Re: [PATCH 2 of 4] xentrace: replace ASSERT with printk in __trace_var

Re: [Xen-devel] [PATCH 3 of 4] xentrace: reduce size of extradata in trace_irq_mask()

Re: [Xen-devel] [PATCH 4 of 4] Add a trace hypercall to allow tracing from dom0 or domU

Re: [Xen-devel] Re: [PATCH 2 of 4] xentrace: replace ASSERT with printk in __trace_var

Re: [Xen-devel] Re: [PATCH 2 of 4] xentrace: replace ASSERT with printk in __trace_var

Re: [Xen-devel] Re: [PATCH 2 of 4] xentrace: replace ASSERT with printk in __trace_var

Re: [Xen-devel] Re: [PATCH 2 of 4] xentrace: replace ASSERT with printk in __trace_var

Re: [Xen-devel] [PATCH 4 of 4] Add a trace hypercall to allow tracing from dom0 or domU

Re: [Xen-devel] [PATCH 4 of 4] Add a trace hypercall to allow tracing from dom0 or domU