Re: [Xen-devel] [PATCH 1/2] x86/vmx: Print the problematic MSR if a vmentry fails

[Andrew Cooper]

On 13/10/16 12:38, Jan Beulich wrote:
 On 13.10.16 at 13:15,  wrote:
>> Sample error looks like:
>>
>>   (XEN) Failed vm entry (exit reason 0x8022) caused by MSR loading 
>> (entry 13).
>>   (XEN)   msr 068a, val 1fff80102af0, (mbz 0)
>>   (XEN) * VMCS Area **
>>
>> Signed-off-by: Andrew Cooper 
> Reviewed-by: Jan Beulich 
> with
>
>> --- a/xen/arch/x86/hvm/vmx/vmx.c
>> +++ b/xen/arch/x86/hvm/vmx/vmx.c
>> @@ -3104,8 +3104,23 @@ static void vmx_failed_vmentry(unsigned int 
>> exit_reason,
>>  printk("caused by invalid guest state (%ld).\n", 
>> exit_qualification);
>>  break;
>>  case EXIT_REASON_MSR_LOADING:
>> -printk("caused by MSR entry %ld loading.\n", exit_qualification);
>> +{
>> +unsigned long idx = exit_qualification - 1;
>> +struct vmx_msr_entry *msr;
> ... preferably const here

Will do.

>  (and the declaration perhaps moved into
> the more narrow scope it's needed in), ...

Cant, due to its use in the sizeof() expression.  (I tried that first)

>
>> +printk("caused by MSR loading (entry %ld).\n", idx);
> ... %lu (plus ideally the full stop dropped) here, and ...

Ok for %lu.  The full stop is dealt with in the following patch, so will
leave this as-is for consistency of both patches.

>
>> +if ( idx > (PAGE_SIZE / sizeof(*msr)) )
> ... >= here.
>
>> +printk("  Entry out of range\n");
>> +else
>> +{
>> +msr = >arch.hvm_vmx.msr_area[idx];
>> +
>> +printk("  msr %08x, val %016"PRIx64", (mbz %#x)\n",
> I'm also unsure about the usefulness of the commas here - at least
> the second one seems a little strange with the value in parentheses.

Ok.

~Andrew

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Re: [Xen-devel] [PATCH 1/2] x86/vmx: Print the problematic MSR if a vmentry fails

[Jan Beulich]

>>> On 13.10.16 at 13:15,  wrote:
> Sample error looks like:
> 
>   (XEN) Failed vm entry (exit reason 0x8022) caused by MSR loading (entry 
> 13).
>   (XEN)   msr 068a, val 1fff80102af0, (mbz 0)
>   (XEN) * VMCS Area **
> 
> Signed-off-by: Andrew Cooper 

Reviewed-by: Jan Beulich 
with

> --- a/xen/arch/x86/hvm/vmx/vmx.c
> +++ b/xen/arch/x86/hvm/vmx/vmx.c
> @@ -3104,8 +3104,23 @@ static void vmx_failed_vmentry(unsigned int 
> exit_reason,
>  printk("caused by invalid guest state (%ld).\n", exit_qualification);
>  break;
>  case EXIT_REASON_MSR_LOADING:
> -printk("caused by MSR entry %ld loading.\n", exit_qualification);
> +{
> +unsigned long idx = exit_qualification - 1;
> +struct vmx_msr_entry *msr;

... preferably const here (and the declaration perhaps moved into
the more narrow scope it's needed in), ...

> +printk("caused by MSR loading (entry %ld).\n", idx);

... %lu (plus ideally the full stop dropped) here, and ...

> +if ( idx > (PAGE_SIZE / sizeof(*msr)) )

... >= here.

> +printk("  Entry out of range\n");
> +else
> +{
> +msr = >arch.hvm_vmx.msr_area[idx];
> +
> +printk("  msr %08x, val %016"PRIx64", (mbz %#x)\n",

I'm also unsure about the usefulness of the commas here - at least
the second one seems a little strange with the value in parentheses.

Jan


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[Xen-devel] [PATCH 1/2] x86/vmx: Print the problematic MSR if a vmentry fails

[Andrew Cooper]

Sample error looks like:

  (XEN) Failed vm entry (exit reason 0x8022) caused by MSR loading (entry 
13).
  (XEN)   msr 068a, val 1fff80102af0, (mbz 0)
  (XEN) * VMCS Area **

Signed-off-by: Andrew Cooper 
---
CC: Jan Beulich 
CC: Jun Nakajima 
CC: Kevin Tian 
---
 xen/arch/x86/hvm/vmx/vmx.c | 17 -
 1 file changed, 16 insertions(+), 1 deletion(-)

diff --git a/xen/arch/x86/hvm/vmx/vmx.c b/xen/arch/x86/hvm/vmx/vmx.c
index b9102ce..38cbcea 100644
--- a/xen/arch/x86/hvm/vmx/vmx.c
+++ b/xen/arch/x86/hvm/vmx/vmx.c
@@ -3104,8 +3104,23 @@ static void vmx_failed_vmentry(unsigned int exit_reason,
 printk("caused by invalid guest state (%ld).\n", exit_qualification);
 break;
 case EXIT_REASON_MSR_LOADING:
-printk("caused by MSR entry %ld loading.\n", exit_qualification);
+{
+unsigned long idx = exit_qualification - 1;
+struct vmx_msr_entry *msr;
+
+printk("caused by MSR loading (entry %ld).\n", idx);
+
+if ( idx > (PAGE_SIZE / sizeof(*msr)) )
+printk("  Entry out of range\n");
+else
+{
+msr = >arch.hvm_vmx.msr_area[idx];
+
+printk("  msr %08x, val %016"PRIx64", (mbz %#x)\n",
+   msr->index, msr->data, msr->mbz);
+}
 break;
+}
 case EXIT_REASON_MCE_DURING_VMENTRY:
 printk("caused by machine check.\n");
 HVMTRACE_0D(MCE);
-- 
2.1.4


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