Re: [Xen-devel] [PATCH 5/8] x86/hvm: Don't raise #GP behind the emulators back for MSR accesses

["Jan Beulich" <JBeulich@xxxxxxxx>]

>>> On 05.12.16 at 17:29, <andrew.cooper3@xxxxxxxxxx> wrote:
> On 05/12/16 12:10, Jan Beulich wrote:
>>>>> On 05.12.16 at 11:09, <andrew.cooper3@xxxxxxxxxx> wrote:
>>> --- a/xen/arch/x86/hvm/hvm.c
>>> +++ b/xen/arch/x86/hvm/hvm.c
>>> @@ -509,7 +509,11 @@ void hvm_do_resume(struct vcpu *v)
>>>  
>>>          if ( w->do_write.msr )
>>>          {
>>> -            hvm_msr_write_intercept(w->msr, w->value, 0);
>>> +            int rc = hvm_msr_write_intercept(w->msr, w->value, 0);
>>> +
>>> +            if ( rc == X86EMUL_EXCEPTION )
>>> +                hvm_inject_hw_exception(TRAP_gp_fault, 0);
>> The use of a local variable looks kind of pointless here.
> 
> The first version had
> 
> if ( hvm_msr_write_intercept(w->msr, w->value, 0) ==
>      X86EMUL_EXCEPTION )
> 
> but this looked rather ugly to read.  I prefer the version as submitted,
> but am not too fussed if you insist for the latter?

I won't insist, it was just a suggestion to make the code look better
to my eyes. If you like it better as is, keep it.

Jan


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