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

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Message-ID: <CANRm+CxEB3S26qK1OjeN4E4MYC-fVW4MCEEgKi7nJcsCwi4BQA@mail.gmail.com>
Date:   Sun, 11 Feb 2018 18:57:37 +0800
From:   Wanpeng Li <kernellwp@...il.com>
To:     Paolo Bonzini <pbonzini@...hat.com>
Cc:     Xiao Guangrong <guangrong.xiao@...il.com>,
        LKML <linux-kernel@...r.kernel.org>, kvm <kvm@...r.kernel.org>,
        Radim Krčmář <rkrcmar@...hat.com>,
        Dmitry Vyukov <dvyukov@...gle.com>
Subject: Re: [PATCH] KVM: X86: Fix SMRAM accessing even if VM is shutdown

2018-02-09 20:42 GMT+08:00 Paolo Bonzini <pbonzini@...hat.com>:
> 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

After patch v2, I found that instruction fetch causes emulation to
fail since KVM_MEMSLOT_INVALID.

Regards,
Wanpeng Li