The patch below does not apply to the 6.1-stable tree. If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to <stable@xxxxxxxxxxxxxxx>. To reproduce the conflict and resubmit, you may use the following commands: git fetch https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/ linux-6.1.y git checkout FETCH_HEAD git cherry-pick -x b65235f6e102354ccafda601eaa1c5bef5284d21 # <resolve conflicts, build, test, etc.> git commit -s git send-email --to '<stable@xxxxxxxxxxxxxxx>' --in-reply-to '2023102017-human-marine-7125@gregkh' --subject-prefix 'PATCH 6.1.y' HEAD^.. Possible dependencies: thanks, greg k-h ------------------ original commit in Linus's tree ------------------ >From b65235f6e102354ccafda601eaa1c5bef5284d21 Mon Sep 17 00:00:00 2001 From: Maxim Levitsky <mlevitsk@xxxxxxxxxx> Date: Thu, 28 Sep 2023 20:33:51 +0300 Subject: [PATCH] x86: KVM: SVM: always update the x2avic msr interception 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@xxxxxxxxxxxxxxx Signed-off-by: Maxim Levitsky <mlevitsk@xxxxxxxxxx> Reviewed-by: Suravee Suthikulpanit <suravee.suthikulpanit@xxxxxxx> Tested-by: Suravee Suthikulpanit <suravee.suthikulpanit@xxxxxxx> Reviewed-by: Sean Christopherson <seanjc@xxxxxxxxxx> Message-Id: <20230928173354.217464-2-mlevitsk@xxxxxxxxxx> Signed-off-by: Paolo Bonzini <pbonzini@xxxxxxxxxx> diff --git a/arch/x86/kvm/svm/svm.c b/arch/x86/kvm/svm/svm.c index 9507df93f410..acdd0b89e471 100644 --- a/arch/x86/kvm/svm/svm.c +++ b/arch/x86/kvm/svm/svm.c @@ -913,8 +913,7 @@ void svm_set_x2apic_msr_interception(struct vcpu_svm *svm, bool intercept) if (intercept == svm->x2avic_msrs_intercepted) return; - if (!x2avic_enabled || - !apic_x2apic_mode(svm->vcpu.arch.apic)) + if (!x2avic_enabled) return; for (i = 0; i < MAX_DIRECT_ACCESS_MSRS; i++) {
