Re: [PATCH] KVM: x86: Keep MSR_IA32_XSS unchanged for INIT

From: Paolo Bonzini <pbonzini@redhat.com>
To: Xiaoyao Li <xiaoyao.li@intel.com>,
	Sean Christopherson <seanjc@google.com>,
	Wanpeng Li <wanpengli@tencent.com>,
	Vitaly Kuznetsov <vkuznets@redhat.com>,
	Jim Mattson <jmattson@google.com>
Cc: kvm@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH] KVM: x86: Keep MSR_IA32_XSS unchanged for INIT
Date: Wed, 26 Jan 2022 18:15:07 +0100	[thread overview]
Message-ID: <6decc356-b24b-583e-7a96-b221afd91af8@redhat.com> (raw)
In-Reply-To: <20220126034750.2495371-1-xiaoyao.li@intel.com>

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@intel.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