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From: Sean Christopherson <seanjc@google.com>
To: Sean Christopherson <seanjc@google.com>,
	Paolo Bonzini <pbonzini@redhat.com>,
	 Vitaly Kuznetsov <vkuznets@redhat.com>,
	"K. Y. Srinivasan" <kys@microsoft.com>,
	 Haiyang Zhang <haiyangz@microsoft.com>,
	Wei Liu <wei.liu@kernel.org>,  Dexuan Cui <decui@microsoft.com>,
	Long Li <longli@microsoft.com>
Cc: kvm@vger.kernel.org, linux-hyperv@vger.kernel.org,
	 linux-kernel@vger.kernel.org, Jim Mattson <jmattson@google.com>,
	 Yosry Ahmed <yosry.ahmed@linux.dev>
Subject: [PATCH v2 3/8] KVM: SVM: Check for an unexpected VM-Exit after RETPOLINE "fast" handling
Date: Tue, 30 Dec 2025 13:13:42 -0800	[thread overview]
Message-ID: <20251230211347.4099600-4-seanjc@google.com> (raw)
In-Reply-To: <20251230211347.4099600-1-seanjc@google.com>

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@linux.dev>
Signed-off-by: Sean Christopherson <seanjc@google.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


  parent reply	other threads:[~2025-12-30 21:13 UTC|newest]

Thread overview: 13+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2025-12-30 21:13 [PATCH v2 0/8] KVM: SVM: Fix exit_code bugs Sean Christopherson
2025-12-30 21:13 ` [PATCH v2 1/8] KVM: SVM: Add a helper to detect VMRUN failures Sean Christopherson
2026-01-02 16:44   ` Yosry Ahmed
2025-12-30 21:13 ` [PATCH v2 2/8] KVM: SVM: Open code handling of unexpected exits in svm_invoke_exit_handler() Sean Christopherson
2026-01-02 11:41   ` Gupta, Pankaj
2025-12-30 21:13 ` Sean Christopherson [this message]
2025-12-30 21:13 ` [PATCH v2 4/8] KVM: SVM: Filter out 64-bit exit codes when invoking exit handlers on bare metal Sean Christopherson
2025-12-30 21:13 ` [PATCH v2 5/8] KVM: SVM: Treat exit_code as an unsigned 64-bit value through all of KVM Sean Christopherson
2025-12-30 21:13 ` [PATCH v2 6/8] KVM: SVM: Limit incorrect check on SVM_EXIT_ERR to running as a VM Sean Christopherson
2025-12-30 21:13 ` [PATCH v2 7/8] KVM: SVM: Harden exit_code against being used in Spectre-like attacks Sean Christopherson
2025-12-30 21:13 ` [PATCH v2 8/8] KVM: SVM: Assert that Hyper-V's HV_SVM_EXITCODE_ENL == SVM_EXIT_SW Sean Christopherson
2026-01-02  9:58   ` Vitaly Kuznetsov
2026-01-05 15:52     ` Sean Christopherson

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