linux-kernel - [PATCH 5.16 057/200] KVM: x86: Update vCPUs runtime CPUID on write to MSR_IA32

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Date:   Mon, 31 Jan 2022 11:55:20 +0100
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org, Like Xu <likexu@...cent.com>,
        Sean Christopherson <seanjc@...gle.com>,
        Paolo Bonzini <pbonzini@...hat.com>
Subject: [PATCH 5.16 057/200] KVM: x86: Update vCPUs runtime CPUID on write to MSR_IA32_XSS

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

commit 4c282e51e4450b94680d6ca3b10f830483b1f243 upstream.

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>
Message-Id: <20220126172226.2298529-3-seanjc@...gle.com>
Signed-off-by: Paolo Bonzini <pbonzini@...hat.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
---
 arch/x86/kvm/x86.c |    1 +
 1 file changed, 1 insertion(+)

--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -3508,6 +3508,7 @@ int kvm_set_msr_common(struct kvm_vcpu *
 		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)