linux-kernel - [PATCH v2 3/8] KVM: SVM: Check for an unexpected VM-Exit after RETPOLINE "fast" handling

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Message-ID: <20251230211347.4099600-4-seanjc@google.com>
Date: Tue, 30 Dec 2025 13:13:42 -0800
From: Sean Christopherson <seanjc@...gle.com>
To: Sean Christopherson <seanjc@...gle.com>, Paolo Bonzini <pbonzini@...hat.com>, 
	Vitaly Kuznetsov <vkuznets@...hat.com>, "K. Y. Srinivasan" <kys@...rosoft.com>, 
	Haiyang Zhang <haiyangz@...rosoft.com>, Wei Liu <wei.liu@...nel.org>, 
	Dexuan Cui <decui@...rosoft.com>, Long Li <longli@...rosoft.com>
Cc: kvm@...r.kernel.org, linux-hyperv@...r.kernel.org, 
	linux-kernel@...r.kernel.org, Jim Mattson <jmattson@...gle.com>, 
	Yosry Ahmed <yosry.ahmed@...ux.dev>
Subject: [PATCH v2 3/8] KVM: SVM: Check for an unexpected VM-Exit after
 RETPOLINE "fast" handling

Check for an unexpected/unhandled VM-Exit after the manual RETPOLINE=y
handling.  The entire point of the RETPOLINE checks is to optimize for
common VM-Exits, i.e. checking for the rare case of an unsupported
VM-Exit is counter-productive.  This also aligns SVM and VMX exit handling.

No functional change intended.

Reviewed-by: Yosry Ahmed <yosry.ahmed@...ux.dev>
Signed-off-by: Sean Christopherson <seanjc@...gle.com>
---
 arch/x86/kvm/svm/svm.c | 12 ++++++------
 1 file changed, 6 insertions(+), 6 deletions(-)

diff --git a/arch/x86/kvm/svm/svm.c b/arch/x86/kvm/svm/svm.c
index a523011f0923..e24bedf1fc81 100644
--- a/arch/x86/kvm/svm/svm.c
+++ b/arch/x86/kvm/svm/svm.c
@@ -3445,12 +3445,6 @@ static void dump_vmcb(struct kvm_vcpu *vcpu)
 
 int svm_invoke_exit_handler(struct kvm_vcpu *vcpu, u64 exit_code)
 {
-	if (exit_code >= ARRAY_SIZE(svm_exit_handlers))
-		goto unexpected_vmexit;
-
-	if (!svm_exit_handlers[exit_code])
-		goto unexpected_vmexit;
-
 #ifdef CONFIG_MITIGATION_RETPOLINE
 	if (exit_code == SVM_EXIT_MSR)
 		return msr_interception(vcpu);
@@ -3467,6 +3461,12 @@ int svm_invoke_exit_handler(struct kvm_vcpu *vcpu, u64 exit_code)
 		return sev_handle_vmgexit(vcpu);
 #endif
 #endif
+	if (exit_code >= ARRAY_SIZE(svm_exit_handlers))
+		goto unexpected_vmexit;
+
+	if (!svm_exit_handlers[exit_code])
+		goto unexpected_vmexit;
+
 	return svm_exit_handlers[exit_code](vcpu);
 
 unexpected_vmexit:
-- 
2.52.0.351.gbe84eed79e-goog