linux-kernel - [PATCH v2 34/46] KVM: VMX: Refresh list of user return MSRs after setting guest CPUID

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Date:   Tue, 13 Jul 2021 09:33:12 -0700
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, Reiji Watanabe <reijiw@...gle.com>
Subject: [PATCH v2 34/46] KVM: VMX: Refresh list of user return MSRs after
 setting guest CPUID

After a CPUID update, refresh the list of user return MSRs that are
loaded into hardware when running the vCPU.  This is necessary to handle
the oddball case where userspace exposes X86_FEATURE_RDTSCP to the guest
after the vCPU is running.

Fixes: 0023ef39dc35 ("kvm: vmx: Set IA32_TSC_AUX for legacy mode guests")
Fixes: 4e47c7a6d714 ("KVM: VMX: Add instruction rdtscp support for guest")
Reviewed-by: Reiji Watanabe <reijiw@...gle.com>
Signed-off-by: Sean Christopherson <seanjc@...gle.com>
---
 arch/x86/kvm/vmx/vmx.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/arch/x86/kvm/vmx/vmx.c b/arch/x86/kvm/vmx/vmx.c
index d7a4db15a169..3045daa3ec30 100644
--- a/arch/x86/kvm/vmx/vmx.c
+++ b/arch/x86/kvm/vmx/vmx.c
@@ -7159,6 +7159,8 @@ static void vmx_vcpu_after_set_cpuid(struct kvm_vcpu *vcpu)
 	/* xsaves_enabled is recomputed in vmx_compute_secondary_exec_control(). */
 	vcpu->arch.xsaves_enabled = false;
 
+	vmx_setup_uret_msrs(vmx);
+
 	if (cpu_has_secondary_exec_ctrls()) {
 		vmx_compute_secondary_exec_control(vmx);
 		vmcs_set_secondary_exec_control(vmx);
-- 
2.32.0.93.g670b81a890-goog