Commit 23ca102e authored by Sean Christopherson's avatar Sean Christopherson
Browse files

KVM: VMX: Stop walking list of routing table entries when updating IRTE 

Now that KVM provides the to-be-updated routing entry, 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. the for-loop can only process one entry.

Link: https://lore.kernel.org/r/20250611224604.313496-26-seanjc@google.com


Signed-off-by: default avatarSean Christopherson <seanjc@google.com>
parent 1e663ed2

arch/x86/kvm/vmx/posted_intr.c

+28 −62
Original line number Diff line number Diff line
@@ -302,33 +302,13 @@ int vmx_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;

	struct kvm_lapic_irq irq;

	struct kvm_vcpu *vcpu;

	struct vcpu_data vcpu_info;

	bool set = !!new;

	int idx, ret = 0;



	if (!vmx_can_use_vtd_pi(kvm))

		return 0;



	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) {

		if (e->type != KVM_IRQ_ROUTING_MSI)

			continue;



		WARN_ON_ONCE(new && memcmp(e, new, sizeof(*new)));



	/*

	 * VT-d PI cannot support posting multicast/broadcast

	 * interrupts to a vCPU, we still use interrupt remapping
@@ -344,36 +324,22 @@ int vmx_pi_update_irte(struct kvm_kernel_irqfd *irqfd, struct kvm *kvm, 
	 * In addition, we can only inject generic interrupts using

	 * the PI mechanism, refuse to route others through it.

	 */

	if (!new || new->type != KVM_IRQ_ROUTING_MSI)

		goto do_remapping;



	kvm_set_msi_irq(kvm, new, &irq);



		kvm_set_msi_irq(kvm, e, &irq);

	if (!kvm_intr_is_single_vcpu(kvm, &irq, &vcpu) ||

	    !kvm_irq_is_postable(&irq))

			continue;

		goto do_remapping;



	vcpu_info.pi_desc_addr = __pa(vcpu_to_pi_desc(vcpu));

	vcpu_info.vector = irq.vector;



		trace_kvm_pi_irte_update(host_irq, vcpu->vcpu_id, e->gsi,

				vcpu_info.vector, vcpu_info.pi_desc_addr, set);



		if (!set)

			continue;



		enable_remapped_mode = false;



		ret = irq_set_vcpu_affinity(host_irq, &vcpu_info);

		if (ret < 0) {

			printk(KERN_INFO "%s: failed to update PI IRTE\n",

					__func__);

			goto out;

		}

	}



	if (enable_remapped_mode)

		ret = irq_set_vcpu_affinity(host_irq, NULL);

	trace_kvm_pi_irte_update(host_irq, vcpu->vcpu_id, guest_irq,

				 vcpu_info.vector, vcpu_info.pi_desc_addr, true);



	ret = 0;

out:

	srcu_read_unlock(&kvm->irq_srcu, idx);

	return ret;

	return irq_set_vcpu_affinity(host_irq, &vcpu_info);

do_remapping:

	return irq_set_vcpu_affinity(host_irq, NULL);

}