From: Sean Christopherson Date: Tue, 3 Feb 2026 19:07:09 +0000 (-0800) Subject: KVM: SVM: Initialize AVIC VMCB fields if AVIC is enabled with in-kernel APIC X-Git-Tag: v7.0-rc4~4^2~8 X-Git-Url: http://git.ipfire.org/gitweb.cgi?a=commitdiff_plain;h=3989a6d036c8ec82c0de3614bed23a1dacd45de5;p=thirdparty%2Flinux.git KVM: SVM: Initialize AVIC VMCB fields if AVIC is enabled with in-kernel APIC Initialize all per-vCPU AVIC control fields in the VMCB if AVIC is enabled in KVM and the VM has an in-kernel local APIC, i.e. if it's _possible_ the vCPU could activate AVIC at any point in its lifecycle. Configuring the VMCB if and only if AVIC is active "works" purely because of optimizations in kvm_create_lapic() to speculatively set apicv_active if AVIC is enabled *and* to defer updates until the first KVM_RUN. In quotes because KVM likely won't do the right thing if kvm_apicv_activated() is false, i.e. if a vCPU is created while APICv is inhibited at the VM level for whatever reason. E.g. if the inhibit is *removed* before KVM_REQ_APICV_UPDATE is handled in KVM_RUN, then __kvm_vcpu_update_apicv() will elide calls to vendor code due to seeing "apicv_active == activate". Cleaning up the initialization code will also allow fixing a bug where KVM incorrectly leaves CR8 interception enabled when AVIC is activated without creating a mess with respect to whether AVIC is activated or not. Cc: stable@vger.kernel.org Fixes: 67034bb9dd5e ("KVM: SVM: Add irqchip_split() checks before enabling AVIC") Fixes: 6c3e4422dd20 ("svm: Add support for dynamic APICv") Reviewed-by: Naveen N Rao (AMD) Reviewed-by: Jim Mattson Link: https://patch.msgid.link/20260203190711.458413-2-seanjc@google.com Signed-off-by: Sean Christopherson Signed-off-by: Paolo Bonzini --- diff --git a/arch/x86/kvm/svm/avic.c b/arch/x86/kvm/svm/avic.c index f92214b1a938..44e07c27b190 100644 --- a/arch/x86/kvm/svm/avic.c +++ b/arch/x86/kvm/svm/avic.c @@ -368,7 +368,7 @@ void avic_init_vmcb(struct vcpu_svm *svm, struct vmcb *vmcb) vmcb->control.avic_physical_id = __sme_set(__pa(kvm_svm->avic_physical_id_table)); vmcb->control.avic_vapic_bar = APIC_DEFAULT_PHYS_BASE; - if (kvm_apicv_activated(svm->vcpu.kvm)) + if (kvm_vcpu_apicv_active(&svm->vcpu)) avic_activate_vmcb(svm); else avic_deactivate_vmcb(svm); diff --git a/arch/x86/kvm/svm/svm.c b/arch/x86/kvm/svm/svm.c index 8f8bc863e214..7806321c37bc 100644 --- a/arch/x86/kvm/svm/svm.c +++ b/arch/x86/kvm/svm/svm.c @@ -1189,7 +1189,7 @@ static void init_vmcb(struct kvm_vcpu *vcpu, bool init_event) if (guest_cpu_cap_has(vcpu, X86_FEATURE_ERAPS)) svm->vmcb->control.erap_ctl |= ERAP_CONTROL_ALLOW_LARGER_RAP; - if (kvm_vcpu_apicv_active(vcpu)) + if (enable_apicv && irqchip_in_kernel(vcpu->kvm)) avic_init_vmcb(svm, vmcb); if (vnmi)