linux-kernel - Re: [PATCH] KVM: X86: Allow userspace to define the microcode version

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Message-ID: <20180226114409.GD4377@pd.tnic>
Date:   Mon, 26 Feb 2018 12:44:09 +0100
From:   Borislav Petkov <bp@...en8.de>
To:     Wanpeng Li <kernellwp@...il.com>
Cc:     LKML <linux-kernel@...r.kernel.org>, kvm <kvm@...r.kernel.org>,
        Paolo Bonzini <pbonzini@...hat.com>,
        Radim Krčmář <rkrcmar@...hat.com>
Subject: Re: [PATCH] KVM: X86: Allow userspace to define the microcode version

On Mon, Feb 26, 2018 at 07:37:32PM +0800, Wanpeng Li wrote:
> The guest write is ignored as the original kvm implementation before the patch.

That will never work because there's no virtualized microcode loader.
Which will be a dumb idea anyway.

Goes to show that dealing with microcode revisions for a guest is the
wrong approach.

> Hmm, the apic_check_deadline_errata() example can be referred to.

So that's basically what I'm saying - fix apic_check_deadline_errata()
to check whether the kernel runs as a guest.

-- 
Regards/Gruss,
    Boris.

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