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>
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 5/9] KVM: SVM: Check for an unexpected VM-Exit after RETPOLINE "fast" handling
Date: Thu, 13 Nov 2025 14:56:17 -0800 [thread overview]
Message-ID: <20251113225621.1688428-6-seanjc@google.com> (raw)
In-Reply-To: <20251113225621.1688428-1-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.
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 638a67ef0c37..202a4d8088a2 100644
--- a/arch/x86/kvm/svm/svm.c
+++ b/arch/x86/kvm/svm/svm.c
@@ -3435,12 +3435,6 @@ 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);
@@ -3457,6 +3451,12 @@ 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.rc1.455.g30608eb744-goog
next prev parent reply other threads:[~2025-11-13 22:56 UTC|newest]
Thread overview: 31+ messages / expand[flat|nested] mbox.gz Atom feed top
2025-11-13 22:56 [PATCH 0/9] KVM: SVM: Fix (hilarious) exit_code bugs Sean Christopherson
2025-11-13 22:56 ` [PATCH 1/9] KVM: nSVM: Clear exit_code_hi in VMCB when synthesizing nested VM-Exits Sean Christopherson
2025-11-13 23:03 ` Yosry Ahmed
2025-11-13 22:56 ` [PATCH 2/9] KVM: nSVM: Set exit_code_hi to -1 when synthesizing SVM_EXIT_ERR (failed VMRUN) Sean Christopherson
2025-11-13 23:17 ` Yosry Ahmed
2025-11-13 23:28 ` Yosry Ahmed
2025-11-13 22:56 ` [PATCH 3/9] KVM: SVM: Add a helper to detect VMRUN failures Sean Christopherson
2025-11-13 23:30 ` Yosry Ahmed
2025-11-13 23:35 ` Sean Christopherson
2025-11-13 22:56 ` [PATCH 4/9] KVM: SVM: Open code handling of unexpected exits in svm_invoke_exit_handler() Sean Christopherson
2025-11-13 23:33 ` Yosry Ahmed
2025-11-13 22:56 ` Sean Christopherson [this message]
2025-11-14 0:04 ` [PATCH 5/9] KVM: SVM: Check for an unexpected VM-Exit after RETPOLINE "fast" handling Yosry Ahmed
2025-11-13 22:56 ` [PATCH 6/9] KVM: SVM: Filter out 64-bit exit codes when invoking exit handlers on bare metal Sean Christopherson
2025-11-14 0:06 ` Yosry Ahmed
2025-11-14 23:32 ` Paolo Bonzini
2025-11-19 22:05 ` Sean Christopherson
2025-11-13 22:56 ` [PATCH 7/9] KVM: SVM: Treat exit_code as an unsigned 64-bit value through all of KVM Sean Christopherson
2025-11-14 0:08 ` Yosry Ahmed
2025-11-14 5:26 ` Michael Kelley
2025-11-14 15:22 ` Sean Christopherson
2025-11-14 18:29 ` Wei Liu
2025-11-14 18:35 ` Sean Christopherson
2025-11-14 18:40 ` Wei Liu
2025-11-14 15:27 ` Sean Christopherson
2025-11-14 15:47 ` Sean Christopherson
2025-11-14 23:33 ` Paolo Bonzini
2025-11-13 22:56 ` [PATCH 8/9] KVM: SVM: Limit incorrect check on SVM_EXIT_ERR to running as a VM Sean Christopherson
2025-11-14 0:11 ` Yosry Ahmed
2025-11-13 22:56 ` [PATCH 9/9] KVM: SVM: Harden exit_code against being used in Spectre-like attacks Sean Christopherson
2025-12-05 16:59 ` [PATCH 0/9] KVM: SVM: Fix (hilarious) exit_code bugs Sean Christopherson
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