From: Sean Christopherson Date: Tue, 1 Apr 2025 16:18:03 +0000 (-0700) Subject: KVM: SVM: Don't update IRTEs if APICv/AVIC is disabled X-Git-Tag: v6.15-rc4~17^2~10 X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=6560aff981ada9aec8163509a59d8f48283263d6;p=thirdparty%2Fkernel%2Fstable.git KVM: SVM: Don't update IRTEs if APICv/AVIC is disabled Skip IRTE updates if AVIC is disabled/unsupported, as forcing the IRTE into remapped mode (kvm_vcpu_apicv_active() will never be true) is unnecessary and wasteful. The IOMMU driver is responsible for putting IRTEs into remapped mode when an IRQ is allocated by a device, long before that device is assigned to a VM. I.e. the kernel as a whole has major issues if the IRTE isn't already in remapped mode. Opportunsitically kvm_arch_has_irq_bypass() to query for APICv/AVIC, so so that all checks in KVM x86 incorporate the same information. Cc: Yosry Ahmed Cc: Jim Mattson Signed-off-by: Sean Christopherson Message-ID: <20250401161804.842968-3-seanjc@google.com> Signed-off-by: Paolo Bonzini --- diff --git a/arch/x86/kvm/svm/avic.c b/arch/x86/kvm/svm/avic.c index 65fd245a9953c..901d8d2dc1691 100644 --- a/arch/x86/kvm/svm/avic.c +++ b/arch/x86/kvm/svm/avic.c @@ -898,8 +898,7 @@ int avic_pi_update_irte(struct kvm *kvm, unsigned int host_irq, struct kvm_irq_routing_table *irq_rt; int idx, ret = 0; - if (!kvm_arch_has_assigned_device(kvm) || - !irq_remapping_cap(IRQ_POSTING_CAP)) + if (!kvm_arch_has_assigned_device(kvm) || !kvm_arch_has_irq_bypass()) return 0; pr_debug("SVM: %s: host_irq=%#x, guest_irq=%#x, set=%#x\n",