linux-kernel - Re: [PATCH] KVM: X86: Fix SMRAM accessing even if VM is shutdown

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Date:   Sun, 11 Feb 2018 11:20:23 +0800
From:   Xiao Guangrong <guangrong.xiao@...il.com>
To:     Paolo Bonzini <pbonzini@...hat.com>,
        Wanpeng Li <kernellwp@...il.com>, linux-kernel@...r.kernel.org,
        kvm@...r.kernel.org
Cc:     Radim Krčmář <rkrcmar@...hat.com>,
        Dmitry Vyukov <dvyukov@...gle.com>
Subject: Re: [PATCH] KVM: X86: Fix SMRAM accessing even if VM is shutdown



On 02/09/2018 08:42 PM, Paolo Bonzini wrote:
> 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.

Wanpeng, could you please do it? :)