linux-kernel - Re: [PATCH 1/2] kvm/x86: Move MSR_K7

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Date:   Mon, 25 Mar 2019 20:38:49 +0100
From:   Borislav Petkov <bp@...en8.de>
To:     Sean Christopherson <sean.j.christopherson@...el.com>
Cc:     KVM <kvm@...r.kernel.org>, Joerg Roedel <joro@...tes.org>,
        Paolo Bonzini <pbonzini@...hat.com>,
        Radim Krčmář <rkrcmar@...hat.com>,
        Tom Lendacky <thomas.lendacky@....com>,
        Tony Luck <tony.luck@...el.com>,
        Yazen Ghannam <Yazen.Ghannam@....com>,
        LKML <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH 1/2] kvm/x86: Move MSR_K7_HWCR to svm.c

On Mon, Mar 25, 2019 at 12:21:11PM -0700, Sean Christopherson wrote:
> Generally speaking, the goal is to support cross-vendor VMs without having
> to modify the guest kernel, i.e. exact emulation is out of scope.  This
> means "emulating" cross-vendor MSRs that the guest expects to exist to the
> point where the guest won't explode, e.g. in the case of MSR_K7_HWCR, Linux
> expects the MSR to exist on all AMD platforms and AFAICT will die during
> boot if it doesn't.
> 
> The rule of thumb for "what MSRs can a guest reasonably expect to exist"
> is fluid.

Ok, I'll keep it in the common MSR accessors in the next version.

Thx for confirming what I was suspecting.

-- 
Regards/Gruss,
    Boris.

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