Re: [PATCH RFC 3/5] x86: KVM: svm: clear interrupt shadow on all paths in skip_emulated_instruction()

Paolo Bonzini
2019-07-31T16:37:19Z

On 31/07/19 15:50, Vitaly Kuznetsov wrote:
> Jim Mattson <jmattson@google.com> writes:
>
>> On Thu, Jun 20, 2019 at 4:02 AM Vitaly Kuznetsov <vkuznets@redhat.com> wrote:
>>>
>>> Regardless of the way how we skip instruction, interrupt shadow needs to be
>>> cleared.
>>
>> This change is definitely an improvement, but the existing code seems
>> to assume that we never call skip_emulated_instruction on a
>> POP-SS/MOV-to-SS/STI. Is that enforced anywhere?
>
> (before I send v1 of the series) I looked at the current code and I
> don't think it is enforced, however, VMX version does the same and
> honestly I can't think of a situation when we would be doing 'skip' for
> such an instruction.... and there's nothing we can easily enforce from
> skip_emulated_instruction() as we have no idea what the instruction
> is...

I agree, I think a comment is worthwhile but we can live with the
limitation.

Paolo