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

[Andrew Cooper <andrew.cooper3@xxxxxxxxxx>]

On 13/10/16 12:38, Jan Beulich wrote:
>>>> On 13.10.16 at 13:15, <andrew.cooper3@xxxxxxxxxx> wrote:
>> Sample error looks like:
>>
>>   (XEN) Failed vm entry (exit reason 0x80000022) caused by MSR loading 
>> (entry 13).
>>   (XEN)   msr 0000068a, val 1fff800000102af0, (mbz 0)
>>   (XEN) ************* VMCS Area **************
>>
>> Signed-off-by: Andrew Cooper <andrew.cooper3@xxxxxxxxxx>
> Reviewed-by: Jan Beulich <jbeulich@xxxxxxxx>
> 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 = &curr->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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