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Subject: Re: [PATCH RFC 3/5] x86: KVM: svm: clear interrupt shadow on all
 paths in skip_emulated_instruction()
To:     Vitaly Kuznetsov <vkuznets@redhat.com>,
        Jim Mattson <jmattson@google.com>
Cc:     kvm list <kvm@vger.kernel.org>,
        LKML <linux-kernel@vger.kernel.org>,
        =?UTF-8?B?UmFkaW0gS3LEjW3DocWZ?= <rkrcmar@redhat.com>,
        Joerg Roedel <joro@8bytes.org>
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From:   Paolo Bonzini <pbonzini@redhat.com>
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Date:   Wed, 31 Jul 2019 18:37:14 +0200
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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