linux-kernel - Re: [PATCH] KVM: x86: Keep MSR_IA32

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Message-ID: <6decc356-b24b-583e-7a96-b221afd91af8@redhat.com>
Date:   Wed, 26 Jan 2022 18:15:07 +0100
From:   Paolo Bonzini <pbonzini@...hat.com>
To:     Xiaoyao Li <xiaoyao.li@...el.com>,
        Sean Christopherson <seanjc@...gle.com>,
        Wanpeng Li <wanpengli@...cent.com>,
        Vitaly Kuznetsov <vkuznets@...hat.com>,
        Jim Mattson <jmattson@...gle.com>
Cc:     kvm@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] KVM: x86: Keep MSR_IA32_XSS unchanged for INIT

On 1/26/22 04:47, Xiaoyao Li wrote:
> It has been corrected from SDM version 075 that MSR_IA32_XSS is reset to
> zero on Power up and Reset but keeps unchanged on INIT.
> 
> Fixes: a554d207dc46 ("KVM: X86: Processor States following Reset or INIT")
> Signed-off-by: Xiaoyao Li <xiaoyao.li@...el.com>
> ---
>   arch/x86/kvm/x86.c | 3 +--
>   1 file changed, 1 insertion(+), 2 deletions(-)
> 
> diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
> index 55518b7d3b96..c0727939684e 100644
> --- a/arch/x86/kvm/x86.c
> +++ b/arch/x86/kvm/x86.c
> @@ -11257,6 +11257,7 @@ void kvm_vcpu_reset(struct kvm_vcpu *vcpu, bool init_event)
>   		vcpu->arch.msr_misc_features_enables = 0;
>   
>   		vcpu->arch.xcr0 = XFEATURE_MASK_FP;
> +		vcpu->arch.ia32_xss = 0;
>   	}
>   
>   	/* All GPRs except RDX (handled below) are zeroed on RESET/INIT. */
> @@ -11273,8 +11274,6 @@ void kvm_vcpu_reset(struct kvm_vcpu *vcpu, bool init_event)
>   	cpuid_0x1 = kvm_find_cpuid_entry(vcpu, 1, 0);
>   	kvm_rdx_write(vcpu, cpuid_0x1 ? cpuid_0x1->eax : 0x600);
>   
> -	vcpu->arch.ia32_xss = 0;
> -
>   	static_call(kvm_x86_vcpu_reset)(vcpu, init_event);
>   
>   	kvm_set_rflags(vcpu, X86_EFLAGS_FIXED);

Queued, thanks.

Paolo