KVM: x86: Update vCPU's runtime CPUID on write to MSR_IA32_XSS

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@vger.kernel.org
Signed-off-by: Like Xu <likexu@tencent.com>
[sean: split out as a separate patch, adjust Fixes tag]
Signed-off-by: Sean Christopherson <seanjc@google.com>
Message-Id: <20220126172226.2298529-3-seanjc@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index b065e0cfa9985fbf532b235168498a7d8127d00b..4c27c179741fe3ac09d5e4fcdd0fcb37fb2114e1 100644 (file)
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -3453,6 +3453,7 @@ 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)