linux-kernel - [PATCH 2/3] KVM: x86: Update vCPU's runtime CPUID on write to MSR_IA32

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Message-Id: <20220126172226.2298529-3-seanjc@google.com>
Date:   Wed, 26 Jan 2022 17:22:25 +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 2/3] KVM: x86: Update vCPU's runtime CPUID on write to MSR_IA32_XSS

From: Like Xu <likexu@...cent.com>

Do a runtime CPUID update for a vCPU if MSR_IA32_XSS is written, as the
size in bytes of the XSAVE area is affected by the states enabled in XSS.

Fixes: 203000993de5 ("kvm: vmx: add MSR logic for XSAVES")
Cc: stable@...r.kernel.org
Signed-off-by: Like Xu <likexu@...cent.com>
[sean: split out as a separate patch, adjust Fixes tag]
Signed-off-by: Sean Christopherson <seanjc@...gle.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 c0727939684e..13793582f26d 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -3535,6 +3535,7 @@ int kvm_set_msr_common(struct kvm_vcpu *vcpu, struct msr_data *msr_info)
 		if (data & ~supported_xss)
 			return 1;
 		vcpu->arch.ia32_xss = data;
+		kvm_update_cpuid_runtime(vcpu);
 		break;
 	case MSR_SMI_COUNT:
 		if (!msr_info->host_initiated)
-- 
2.35.0.rc0.227.g00780c9af4-goog