From 7ab62e3415fb59289ab6dea31f0cc0237b949200 Mon Sep 17 00:00:00 2001 From: Maxim Levitsky Date: Thu, 28 Sep 2023 20:33:51 +0300 Subject: [PATCH] x86: KVM: SVM: always update the x2avic msr interception commit b65235f6e102354ccafda601eaa1c5bef5284d21 upstream. The following problem exists since x2avic was enabled in the KVM: svm_set_x2apic_msr_interception is called to enable the interception of the x2apic msrs. In particular it is called at the moment the guest resets its apic. Assuming that the guest's apic was in x2apic mode, the reset will bring it back to the xapic mode. The svm_set_x2apic_msr_interception however has an erroneous check for '!apic_x2apic_mode()' which prevents it from doing anything in this case. As a result of this, all x2apic msrs are left unintercepted, and that exposes the bare metal x2apic (if enabled) to the guest. Oops. Remove the erroneous '!apic_x2apic_mode()' check to fix that. This fixes CVE-2023-5090 Fixes: 4d1d7942e36a ("KVM: SVM: Introduce logic to (de)activate x2AVIC mode") Cc: stable@vger.kernel.org Signed-off-by: Maxim Levitsky Reviewed-by: Suravee Suthikulpanit Tested-by: Suravee Suthikulpanit Reviewed-by: Sean Christopherson Message-Id: <20230928173354.217464-2-mlevitsk@redhat.com> Signed-off-by: Paolo Bonzini Signed-off-by: SeongJae Park Signed-off-by: Greg Kroah-Hartman --- arch/x86/kvm/svm/svm.c | 3 +-- 1 file changed, 1 insertion(+), 2 deletions(-) diff --git a/arch/x86/kvm/svm/svm.c b/arch/x86/kvm/svm/svm.c index c871a6d..4194aa4 100644 --- a/arch/x86/kvm/svm/svm.c +++ b/arch/x86/kvm/svm/svm.c @@ -822,8 +822,7 @@ void svm_set_x2apic_msr_interception(struct vcpu_svm *svm, bool intercept) if (intercept == svm->x2avic_msrs_intercepted) return; - if (avic_mode != AVIC_MODE_X2 || - !apic_x2apic_mode(svm->vcpu.arch.apic)) + if (avic_mode != AVIC_MODE_X2) return; for (i = 0; i < MAX_DIRECT_ACCESS_MSRS; i++) { -- 2.7.4