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

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Message-ID: <5664ca7f-f391-0301-3a0d-666b73f17b15@redhat.com>
Date:   Thu, 8 Feb 2018 11:31:12 +0100
From:   Paolo Bonzini <pbonzini@...hat.com>
To:     Xiao Guangrong <guangrong.xiao@...il.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 08/02/2018 09:57, Xiao Guangrong wrote:
>> Maybe it should return RET_PF_EMULATE, which would cause an emulation
>> failure and then an exit with KVM_EXIT_INTERNAL_ERROR.
> 
> So the root cause is that a running vCPU accessing the memory whose memslot
> is being updated (met the condition KVM_MEMSLOT_INVALID is set on the its
> memslot).
> 
> The normal #PF handler breaks KVM_RUN and returns -EFAULT to userspace,
> we'd better to make ept-misconfig's handler follow this style as well.

Why return -EFAULT and not attempt emulation (which will fail)?

Paolo