linux-kernel - Re: [PATCH v3 06/21] KVM:x86: Report XSS as to-be-saved if there are supported features

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Message-ID: <ZG23e/zYAiRlfrk9@chao-email>
Date:   Wed, 24 May 2023 15:06:35 +0800
From:   Chao Gao <chao.gao@...el.com>
To:     Yang Weijiang <weijiang.yang@...el.com>
CC:     <seanjc@...gle.com>, <pbonzini@...hat.com>, <kvm@...r.kernel.org>,
        <linux-kernel@...r.kernel.org>, <peterz@...radead.org>,
        <rppt@...nel.org>, <binbin.wu@...ux.intel.com>,
        <rick.p.edgecombe@...el.com>, <john.allen@....com>,
        Sean Christopherson <sean.j.christopherson@...el.com>
Subject: Re: [PATCH v3 06/21] KVM:x86: Report XSS as to-be-saved if there are
 supported features

On Thu, May 11, 2023 at 12:08:42AM -0400, Yang Weijiang wrote:
>From: Sean Christopherson <sean.j.christopherson@...el.com>
>
>Add MSR_IA32_XSS to the list of MSRs reported to userspace if
>supported_xss is non-zero, i.e. KVM supports at least one XSS based
>feature.

The changelog doesn't match what the patch does.

Do you need to check if supported_xss is non-zero in kvm_probe_msr_to_save(),
e.g.,
        case MSR_IA32_XSS:
                if (!kvm_caps.supported_xss)
                        return;
                break;

>
>Signed-off-by: Sean Christopherson <sean.j.christopherson@...el.com>
>Signed-off-by: Yang Weijiang <weijiang.yang@...el.com>
>---
> arch/x86/kvm/x86.c | 1 +
> 1 file changed, 1 insertion(+)
>
>diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
>index e7f78fe79b32..33a780fe820b 100644
>--- a/arch/x86/kvm/x86.c
>+++ b/arch/x86/kvm/x86.c
>@@ -1454,6 +1454,7 @@ static const u32 msrs_to_save_base[] = {
> 	MSR_IA32_UMWAIT_CONTROL,
> 
> 	MSR_IA32_XFD, MSR_IA32_XFD_ERR,
>+	MSR_IA32_XSS,
> };
> 
> static const u32 msrs_to_save_pmu[] = {
>-- 
>2.27.0
>