From 1e663ed239923447a0217d78a96bcdc8729022e0 Mon Sep 17 00:00:00 2001 From: Sean Christopherson Date: Wed, 11 Jun 2025 15:45:26 -0700 Subject: [PATCH] KVM: SVM: Stop walking list of routing table entries when updating IRTE Now that KVM explicitly passes the new/current GSI routing to pi_update_irte(), simply use the provided routing entry and stop walking the routing table to find that entry. KVM, via setup_routing_entry() and sanity checked by kvm_get_msi_route(), disallows having a GSI configured to trigger multiple MSIs. I.e. this is subtly a glorified nop, as KVM allows at most one MSI per GSI, the for-loop can only ever process one entry, and that entry is the new/current entry (see the WARN_ON_ONCE() added by "KVM: x86: Pass new routing entries and irqfd when updating IRTEs" to ensure @new matches the entry found in the routing table). Tested-by: Sairaj Kodilkar Link: https://lore.kernel.org/r/20250611224604.313496-25-seanjc@google.com Signed-off-by: Sean Christopherson --- arch/x86/kvm/svm/avic.c | 107 ++++++++++++++++------------------------ 1 file changed, 43 insertions(+), 64 deletions(-) diff --git a/arch/x86/kvm/svm/avic.c b/arch/x86/kvm/svm/avic.c index e09722f5b5fab..a1a5b86a37fef 100644 --- a/arch/x86/kvm/svm/avic.c +++ b/arch/x86/kvm/svm/avic.c @@ -844,11 +844,10 @@ int avic_pi_update_irte(struct kvm_kernel_irqfd *irqfd, struct kvm *kvm, unsigned int host_irq, uint32_t guest_irq, struct kvm_kernel_irq_routing_entry *new) { - struct kvm_kernel_irq_routing_entry *e; - struct kvm_irq_routing_table *irq_rt; bool enable_remapped_mode = true; - bool set = !!new; - int idx, ret = 0; + struct vcpu_data vcpu_info; + struct vcpu_svm *svm = NULL; + int ret = 0; if (!kvm_arch_has_assigned_device(kvm) || !kvm_arch_has_irq_bypass()) return 0; @@ -860,72 +859,53 @@ int avic_pi_update_irte(struct kvm_kernel_irqfd *irqfd, struct kvm *kvm, svm_ir_list_del(irqfd); pr_debug("SVM: %s: host_irq=%#x, guest_irq=%#x, set=%#x\n", - __func__, host_irq, guest_irq, set); - - idx = srcu_read_lock(&kvm->irq_srcu); - irq_rt = srcu_dereference(kvm->irq_routing, &kvm->irq_srcu); - - if (guest_irq >= irq_rt->nr_rt_entries || - hlist_empty(&irq_rt->map[guest_irq])) { - pr_warn_once("no route for guest_irq %u/%u (broken user space?)\n", - guest_irq, irq_rt->nr_rt_entries); - goto out; - } - - hlist_for_each_entry(e, &irq_rt->map[guest_irq], link) { - struct vcpu_data vcpu_info; - struct vcpu_svm *svm = NULL; + __func__, host_irq, guest_irq, !!new); + + /** + * Here, we setup with legacy mode in the following cases: + * 1. When cannot target interrupt to a specific vcpu. + * 2. Unsetting posted interrupt. + * 3. APIC virtualization is disabled for the vcpu. + * 4. IRQ has incompatible delivery mode (SMI, INIT, etc) + */ + if (new && new->type == KVM_IRQ_ROUTING_MSI && + !get_pi_vcpu_info(kvm, new, &vcpu_info, &svm) && + kvm_vcpu_apicv_active(&svm->vcpu)) { + struct amd_iommu_pi_data pi; - if (e->type != KVM_IRQ_ROUTING_MSI) - continue; + enable_remapped_mode = false; - WARN_ON_ONCE(new && memcmp(e, new, sizeof(*new))); + /* + * Try to enable guest_mode in IRTE. Note, the address + * of the vCPU's AVIC backing page is passed to the + * IOMMU via vcpu_info->pi_desc_addr. + */ + pi.ga_tag = AVIC_GATAG(to_kvm_svm(kvm)->avic_vm_id, + svm->vcpu.vcpu_id); + pi.is_guest_mode = true; + pi.vcpu_data = &vcpu_info; + ret = irq_set_vcpu_affinity(host_irq, &pi); /** - * Here, we setup with legacy mode in the following cases: - * 1. When cannot target interrupt to a specific vcpu. - * 2. Unsetting posted interrupt. - * 3. APIC virtualization is disabled for the vcpu. - * 4. IRQ has incompatible delivery mode (SMI, INIT, etc) + * Here, we successfully setting up vcpu affinity in + * IOMMU guest mode. Now, we need to store the posted + * interrupt information in a per-vcpu ir_list so that + * we can reference to them directly when we update vcpu + * scheduling information in IOMMU irte. */ - if (!get_pi_vcpu_info(kvm, e, &vcpu_info, &svm) && set && - kvm_vcpu_apicv_active(&svm->vcpu)) { - struct amd_iommu_pi_data pi; - - enable_remapped_mode = false; - - /* - * Try to enable guest_mode in IRTE. Note, the address - * of the vCPU's AVIC backing page is passed to the - * IOMMU via vcpu_info->pi_desc_addr. - */ - pi.ga_tag = AVIC_GATAG(to_kvm_svm(kvm)->avic_vm_id, - svm->vcpu.vcpu_id); - pi.is_guest_mode = true; - pi.vcpu_data = &vcpu_info; - ret = irq_set_vcpu_affinity(host_irq, &pi); - - /** - * Here, we successfully setting up vcpu affinity in - * IOMMU guest mode. Now, we need to store the posted - * interrupt information in a per-vcpu ir_list so that - * we can reference to them directly when we update vcpu - * scheduling information in IOMMU irte. - */ - if (!ret && pi.is_guest_mode) - svm_ir_list_add(svm, irqfd, &pi); - } + if (!ret) + ret = svm_ir_list_add(svm, irqfd, &pi); + } - if (!ret && svm) { - trace_kvm_pi_irte_update(host_irq, svm->vcpu.vcpu_id, - e->gsi, vcpu_info.vector, - vcpu_info.pi_desc_addr, set); - } + if (!ret && svm) { + trace_kvm_pi_irte_update(host_irq, svm->vcpu.vcpu_id, + guest_irq, vcpu_info.vector, + vcpu_info.pi_desc_addr, !!new); + } - if (ret < 0) { - pr_err("%s: failed to update PI IRTE\n", __func__); - goto out; - } + if (ret < 0) { + pr_err("%s: failed to update PI IRTE\n", __func__); + goto out; } if (enable_remapped_mode) @@ -933,7 +913,6 @@ int avic_pi_update_irte(struct kvm_kernel_irqfd *irqfd, struct kvm *kvm, else ret = 0; out: - srcu_read_unlock(&kvm->irq_srcu, idx); return ret; } -- 2.47.2