linux-kernel - [PATCH 1/3] KVM: x86: Keep MSR_IA32

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Message-Id: <20220126172226.2298529-2-seanjc@google.com>
Date:   Wed, 26 Jan 2022 17:22:24 +0000
From:   Sean Christopherson <seanjc@...gle.com>
To:     Paolo Bonzini <pbonzini@...hat.com>
Cc:     Sean Christopherson <seanjc@...gle.com>,
        Vitaly Kuznetsov <vkuznets@...hat.com>,
        Wanpeng Li <wanpengli@...cent.com>,
        Jim Mattson <jmattson@...gle.com>,
        Joerg Roedel <joro@...tes.org>, kvm@...r.kernel.org,
        linux-kernel@...r.kernel.org, Xiaoyao Li <xiaoyao.li@...el.com>,
        Like Xu <likexu@...cent.com>
Subject: [PATCH 1/3] KVM: x86: Keep MSR_IA32_XSS unchanged for INIT

From: Xiaoyao Li <xiaoyao.li@...el.com>

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")
Cc: stable@...r.kernel.org
Signed-off-by: Xiaoyao Li <xiaoyao.li@...el.com>
Signed-off-by: Sean Christopherson <seanjc@...gle.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);
-- 
2.35.0.rc0.227.g00780c9af4-goog