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

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Message-ID: <CALMp9eTX5x9vchMje6J-Fji6jGfHnz=sPVmSKwO-3zdChAZz=g@mail.gmail.com>
Date:   Mon, 25 Mar 2019 11:05:48 -0700
From:   Jim Mattson <jmattson@...gle.com>
To:     Borislav Petkov <bp@...en8.de>
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 10:17 AM Borislav Petkov <bp@...en8.de> wrote:
>
> From: Borislav Petkov <bp@...e.de>
>
> This is an AMD-specific MSR. Put it where it belongs.
>
> Signed-off-by: Borislav Petkov <bp@...e.de>
> Tested-by: Yazen Ghannam <yazen.ghannam@....com>
> ---
>  arch/x86/kvm/svm.c | 14 ++++++++++++++
>  arch/x86/kvm/x86.c | 12 ------------
>  2 files changed, 14 insertions(+), 12 deletions(-)
>
> diff --git a/arch/x86/kvm/svm.c b/arch/x86/kvm/svm.c
> index b5b128a0a051..00eb44a2a377 100644
> --- a/arch/x86/kvm/svm.c
> +++ b/arch/x86/kvm/svm.c
> @@ -4201,6 +4201,9 @@ static int svm_get_msr(struct kvm_vcpu *vcpu, struct msr_data *msr_info)
>         case MSR_F10H_DECFG:
>                 msr_info->data = svm->msr_decfg;
>                 break;
> +       case MSR_K7_HWCR:
> +               msr_info->data = 0;
> +               break;

If the guest has written a non-zero value to this MSR, shouldn't it be
able to read that value back?