linux-kernel - [PATCH v2 06/11] KVM: SVM: add wrappers to enable/disable IRET interception

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Date:   Tue, 29 Nov 2022 21:37:12 +0200
From:   Maxim Levitsky <mlevitsk@...hat.com>
To:     kvm@...r.kernel.org
Cc:     Sandipan Das <sandipan.das@....com>,
        Paolo Bonzini <pbonzini@...hat.com>,
        Jim Mattson <jmattson@...gle.com>,
        Peter Zijlstra <peterz@...radead.org>,
        Dave Hansen <dave.hansen@...ux.intel.com>,
        Borislav Petkov <bp@...en8.de>,
        Pawan Gupta <pawan.kumar.gupta@...ux.intel.com>,
        Thomas Gleixner <tglx@...utronix.de>,
        Ingo Molnar <mingo@...hat.com>,
        Josh Poimboeuf <jpoimboe@...nel.org>,
        Daniel Sneddon <daniel.sneddon@...ux.intel.com>,
        Jiaxi Chen <jiaxi.chen@...ux.intel.com>,
        Babu Moger <babu.moger@....com>, linux-kernel@...r.kernel.org,
        Jing Liu <jing2.liu@...el.com>,
        Wyes Karny <wyes.karny@....com>, x86@...nel.org,
        "H. Peter Anvin" <hpa@...or.com>,
        Sean Christopherson <seanjc@...gle.com>,
        Maxim Levitsky <mlevitsk@...hat.com>
Subject: [PATCH v2 06/11] KVM: SVM: add wrappers to enable/disable IRET interception

SEV-ES guests don't use IRET interception for the detection of
an end of a NMI.

Therefore it makes sense to create a wrapper to avoid repeating
the check for the SEV-ES.

No functional change is intended.

Suggested-by: Sean Christopherson <seanjc@...gle.com>
Signed-off-by: Maxim Levitsky <mlevitsk@...hat.com>
---
 arch/x86/kvm/svm/svm.c | 28 +++++++++++++++++++---------
 1 file changed, 19 insertions(+), 9 deletions(-)

diff --git a/arch/x86/kvm/svm/svm.c b/arch/x86/kvm/svm/svm.c
index 512b2aa21137e2..cfed6ab29c839a 100644
--- a/arch/x86/kvm/svm/svm.c
+++ b/arch/x86/kvm/svm/svm.c
@@ -2468,16 +2468,29 @@ static int task_switch_interception(struct kvm_vcpu *vcpu)
 			       has_error_code, error_code);
 }
 
+static void svm_disable_iret_interception(struct vcpu_svm *svm)
+{
+	if (!sev_es_guest(svm->vcpu.kvm))
+		svm_clr_intercept(svm, INTERCEPT_IRET);
+}
+
+static void svm_enable_iret_interception(struct vcpu_svm *svm)
+{
+	if (!sev_es_guest(svm->vcpu.kvm))
+		svm_set_intercept(svm, INTERCEPT_IRET);
+}
+
 static int iret_interception(struct kvm_vcpu *vcpu)
 {
 	struct vcpu_svm *svm = to_svm(vcpu);
 
 	++vcpu->stat.nmi_window_exits;
 	svm->awaiting_iret_completion = true;
-	if (!sev_es_guest(vcpu->kvm)) {
-		svm_clr_intercept(svm, INTERCEPT_IRET);
+
+	svm_disable_iret_interception(svm);
+	if (!sev_es_guest(vcpu->kvm))
 		svm->nmi_iret_rip = kvm_rip_read(vcpu);
-	}
+
 	kvm_make_request(KVM_REQ_EVENT, vcpu);
 	return 1;
 }
@@ -3470,8 +3483,7 @@ static void svm_inject_nmi(struct kvm_vcpu *vcpu)
 		return;
 
 	svm->nmi_masked = true;
-	if (!sev_es_guest(vcpu->kvm))
-		svm_set_intercept(svm, INTERCEPT_IRET);
+	svm_enable_iret_interception(svm);
 	++vcpu->stat.nmi_injections;
 }
 
@@ -3614,12 +3626,10 @@ static void svm_set_nmi_mask(struct kvm_vcpu *vcpu, bool masked)
 
 	if (masked) {
 		svm->nmi_masked = true;
-		if (!sev_es_guest(vcpu->kvm))
-			svm_set_intercept(svm, INTERCEPT_IRET);
+		svm_enable_iret_interception(svm);
 	} else {
 		svm->nmi_masked = false;
-		if (!sev_es_guest(vcpu->kvm))
-			svm_clr_intercept(svm, INTERCEPT_IRET);
+		svm_disable_iret_interception(svm);
 	}
 }
 
-- 
2.26.3