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From:   Wanpeng Li <kernellwp@gmail.com>
Date:   Tue, 24 Apr 2018 10:56:46 +0800
Message-ID: <CANRm+CwF+=MZK7a+emRbQuA4OueM3pf3ouo2hch9gnRwBLduUA@mail.gmail.com>
Subject: Re: [PATCH] KVM: X86: Allow userspace to define the microcode version
To:     Paolo Bonzini <pbonzini@redhat.com>
Cc:     Borislav Petkov <bp@alien8.de>,
        LKML <linux-kernel@vger.kernel.org>, kvm <kvm@vger.kernel.org>,
        =?UTF-8?B?UmFkaW0gS3LEjW3DocWZ?= <rkrcmar@redhat.com>
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2018-02-26 20:41 GMT+08:00 Paolo Bonzini <pbonzini@redhat.com>:
> On 26/02/2018 13:22, Borislav Petkov wrote:
>> On Mon, Feb 26, 2018 at 01:18:07PM +0100, Paolo Bonzini wrote:
>>>> In this context, "host-initiated" write means written by KVM userspace
>>>> with ioctl(KVM_SET_MSR).  It generally happens only on VM startup, reset
>>>> or live migration.
>>>
>>> To be clear, the target of the write is still the vCPU's emulated MSR.
>>
>> So how am I to imagine this as a user:
>>
>> qemu-system-x86_64 --microcode-revision=0xdeadbeef...
>
> More like "-cpu foo,ucode_rev=0xdeadbeef".  But in practice what would
> happen is one of the following:
>
> 1) "-cpu host" sets ucode_rev to the same value of the host, everyone

I found vmware on my macbook will also do this. :)

Regards,
Wanpeng Li