When allocating the AVIC backing page, only check one of the max AVIC vs. x2AVIC ID based on whether or not x2AVIC is enabled. Doing so fixes a bug where KVM incorrectly inhibits AVIC if x2AVIC is _disabled_ and any vCPU with a non-zero APIC ID is created, as x2avic_max_physical_id is left '0' when x2AVIC is disabled. Fixes: 940fc47cfb0d ("KVM: SVM: Add AVIC support for 4k vCPUs in x2AVIC mode") Cc: stable@vger.kernel.org Cc: Naveen N Rao (AMD) Cc: Suravee Suthikulpanit Signed-off-by: Sean Christopherson --- arch/x86/kvm/svm/avic.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/arch/x86/kvm/svm/avic.c b/arch/x86/kvm/svm/avic.c index 6b77b2033208..0f6c8596719b 100644 --- a/arch/x86/kvm/svm/avic.c +++ b/arch/x86/kvm/svm/avic.c @@ -376,6 +376,7 @@ void avic_init_vmcb(struct vcpu_svm *svm, struct vmcb *vmcb) static int avic_init_backing_page(struct kvm_vcpu *vcpu) { + u32 max_id = x2avic_enabled ? x2avic_max_physical_id : AVIC_MAX_PHYSICAL_ID; struct kvm_svm *kvm_svm = to_kvm_svm(vcpu->kvm); struct vcpu_svm *svm = to_svm(vcpu); u32 id = vcpu->vcpu_id; @@ -388,8 +389,7 @@ static int avic_init_backing_page(struct kvm_vcpu *vcpu) * avic_vcpu_load() expects to be called if and only if the vCPU has * fully initialized AVIC. */ - if ((!x2avic_enabled && id > AVIC_MAX_PHYSICAL_ID) || - (id > x2avic_max_physical_id)) { + if (id > max_id) { kvm_set_apicv_inhibit(vcpu->kvm, APICV_INHIBIT_REASON_PHYSICAL_ID_TOO_BIG); vcpu->arch.apic->apicv_active = false; return 0; base-commit: 9448598b22c50c8a5bb77a9103e2d49f134c9578 -- 2.52.0.457.g6b5491de43-goog