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Subject: Re: [PATCH] KVM: X86: Fix SMRAM accessing even if VM is shutdown
To:     Xiao Guangrong <guangrong.xiao@gmail.com>,
        Wanpeng Li <kernellwp@gmail.com>, linux-kernel@vger.kernel.org,
        kvm@vger.kernel.org
Cc:     =?UTF-8?B?UmFkaW0gS3LEjW3DocWZ?= <rkrcmar@redhat.com>,
        Dmitry Vyukov <dvyukov@google.com>
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From:   Paolo Bonzini <pbonzini@redhat.com>
Message-ID: <0aedd0e5-f5eb-54d8-6f77-e7a12c65fed5@redhat.com>
Date:   Fri, 9 Feb 2018 13:42:51 +0100
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On 09/02/2018 04:22, Xiao Guangrong wrote:
>>
> 
> That is a good question... :)
> 
> This case (with KVM_MEMSLOT_INVALID is set) can be easily constructed,
> userspace should avoid this case by itself (avoiding vCPU accessing the
> memslot which is being updated). If it happens, it's a operation issue
> rather than INTERNAL ERROR.
> 
> Maybe treat it as MMIO accessing and return to userspace with MMIO_EXIT
> is a better solution...

Yeah, that's what emulation would do (except if it's an instruction
fetch, which will cause emulation to fail).  I think it's a bug in the
non-EPT #PF case that we return with -EFAULT.

Paolo