linux-kernel - [PATCH v2 2/3] KVM: SVM: Fix TSC_AUX virtualization intercept update logic

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Date:   Fri, 15 Sep 2023 15:54:31 -0500
From:   Tom Lendacky <thomas.lendacky@....com>
To:     <kvm@...r.kernel.org>, <linux-kernel@...r.kernel.org>,
        <x86@...nel.org>
CC:     Paolo Bonzini <pbonzini@...hat.com>,
        Sean Christopherson <seanjc@...gle.com>,
        Borislav Petkov <bp@...en8.de>,
        Dave Hansen <dave.hansen@...ux.intel.com>,
        Ingo Molnar <mingo@...hat.com>,
        "Thomas Gleixner" <tglx@...utronix.de>,
        Babu Moger <babu.moger@....com>
Subject: [PATCH v2 2/3] KVM: SVM: Fix TSC_AUX virtualization intercept update logic

With the TSC_AUX virtualization support now in the vcpu_set_after_cpuid()
path, the intercepts must be either cleared or set based on the guest
CPUID input. Currently the support only clears the intercepts.

Also, vcpu_set_after_cpuid() calls svm_recalc_instruction_intercepts() as
part of the processing, so the setting or clearing of the RDTSCP intercept
can be dropped from the TSC_AUX virtualization support.

Update the support to always set or clear the TSC_AUX MSR intercept based
on the virtualization requirements.

Fixes: 296d5a17e793 ("KVM: SEV-ES: Use V_TSC_AUX if available instead of RDTSC/MSR_TSC_AUX intercepts")
Signed-off-by: Tom Lendacky <thomas.lendacky@....com>
---
 arch/x86/kvm/svm/sev.c | 11 +++++------
 1 file changed, 5 insertions(+), 6 deletions(-)

diff --git a/arch/x86/kvm/svm/sev.c b/arch/x86/kvm/svm/sev.c
index 4ac01f338903..4900c078045a 100644
--- a/arch/x86/kvm/svm/sev.c
+++ b/arch/x86/kvm/svm/sev.c
@@ -2966,12 +2966,11 @@ static void sev_es_vcpu_after_set_cpuid(struct vcpu_svm *svm)
 {
 	struct kvm_vcpu *vcpu = &svm->vcpu;
 
-	if (boot_cpu_has(X86_FEATURE_V_TSC_AUX) &&
-	    (guest_cpuid_has(vcpu, X86_FEATURE_RDTSCP) ||
-	     guest_cpuid_has(vcpu, X86_FEATURE_RDPID))) {
-		set_msr_interception(vcpu, svm->msrpm, MSR_TSC_AUX, 1, 1);
-		if (guest_cpuid_has(vcpu, X86_FEATURE_RDTSCP))
-			svm_clr_intercept(svm, INTERCEPT_RDTSCP);
+	if (boot_cpu_has(X86_FEATURE_V_TSC_AUX)) {
+		bool v_tsc_aux = guest_cpuid_has(vcpu, X86_FEATURE_RDTSCP) ||
+				 guest_cpuid_has(vcpu, X86_FEATURE_RDPID);
+
+		set_msr_interception(vcpu, svm->msrpm, MSR_TSC_AUX, v_tsc_aux, v_tsc_aux);
 	}
 }
 
-- 
2.41.0