From 39e9c35e447b8ab49ddbc826c40ca31a425e76b2 Mon Sep 17 00:00:00 2001 From: Sean Christopherson Date: Thu, 18 Jun 2026 11:57:45 -0700 Subject: [PATCH] KVM: x86: Replace BUG_ON() with WARN_ON_ONCE() on "bad" nested GPA translation If KVM attempts to translate what it thinks is an L2 GPA with a non-nested MMU, simply WARN and return the GPA, i.e. trust the MMU more than the caller, as there is zero reason to potentially panic the host kernel just because KVM misused an API. Signed-off-by: Sean Christopherson Reviewed-by: Kai Huang Message-ID: <20260618185746.2023283-1-seanjc@google.com> Signed-off-by: Paolo Bonzini --- arch/x86/kvm/svm/nested.c | 3 ++- arch/x86/kvm/vmx/nested.c | 3 ++- 2 files changed, 4 insertions(+), 2 deletions(-) diff --git a/arch/x86/kvm/svm/nested.c b/arch/x86/kvm/svm/nested.c index 9aedb88c832d..3e6c671a8dc2 100644 --- a/arch/x86/kvm/svm/nested.c +++ b/arch/x86/kvm/svm/nested.c @@ -2152,7 +2152,8 @@ static gpa_t svm_translate_nested_gpa(struct kvm_vcpu *vcpu, gpa_t gpa, struct vcpu_svm *svm = to_svm(vcpu); struct kvm_mmu *mmu = vcpu->arch.mmu; - BUG_ON(!mmu_is_nested(vcpu)); + if (WARN_ON_ONCE(!mmu_is_nested(vcpu))) + return gpa; /* Non-GMET walks are always user-walks */ if (!(svm->nested.ctl.misc_ctl & SVM_MISC_ENABLE_GMET)) diff --git a/arch/x86/kvm/vmx/nested.c b/arch/x86/kvm/vmx/nested.c index 3a293640d58c..6957bb6f5cf7 100644 --- a/arch/x86/kvm/vmx/nested.c +++ b/arch/x86/kvm/vmx/nested.c @@ -7470,7 +7470,8 @@ static gpa_t vmx_translate_nested_gpa(struct kvm_vcpu *vcpu, gpa_t gpa, { struct kvm_mmu *mmu = vcpu->arch.mmu; - BUG_ON(!mmu_is_nested(vcpu)); + if (WARN_ON_ONCE(!mmu_is_nested(vcpu))) + return gpa; /* * MBEC differentiates based on the effective U/S bit of