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

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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: Sean Christopherson <seanjc@google.com>
This commit is contained in:
Sean Christopherson
2025-06-11 15:45:27 -07:00
parent 1e663ed239
commit 23ca102e6f
1 changed files with 28 additions and 62 deletions
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90
arch/x86/kvm/vmx/posted_intr.c
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@@ -302,78 +302,44 @@ 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;
}
/*
* VT-d PI cannot support posting multicast/broadcast
* interrupts to a vCPU, we still use interrupt remapping
* for these kind of interrupts.
*
* For lowest-priority interrupts, we only support
* those with single CPU as the destination, e.g. user
* configures the interrupts via /proc/irq or uses
* irqbalance to make the interrupts single-CPU.
*
* We will support full lowest-priority interrupt later.
*
* 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;
hlist_for_each_entry(e, &irq_rt->map[guest_irq], link) {
if (e->type != KVM_IRQ_ROUTING_MSI)
continue;
kvm_set_msi_irq(kvm, new, &irq);
WARN_ON_ONCE(new && memcmp(e, new, sizeof(*new)));
if (!kvm_intr_is_single_vcpu(kvm, &irq, &vcpu) ||
!kvm_irq_is_postable(&irq))
goto do_remapping;
/*
* VT-d PI cannot support posting multicast/broadcast
* interrupts to a vCPU, we still use interrupt remapping
* for these kind of interrupts.
*
* For lowest-priority interrupts, we only support
* those with single CPU as the destination, e.g. user
* configures the interrupts via /proc/irq or uses
* irqbalance to make the interrupts single-CPU.
*
* We will support full lowest-priority interrupt later.
*
* In addition, we can only inject generic interrupts using
* the PI mechanism, refuse to route others through it.
*/
vcpu_info.pi_desc_addr = __pa(vcpu_to_pi_desc(vcpu));
vcpu_info.vector = irq.vector;
kvm_set_msi_irq(kvm, e, &irq);
if (!kvm_intr_is_single_vcpu(kvm, &irq, &vcpu) ||
!kvm_irq_is_postable(&irq))
continue;
trace_kvm_pi_irte_update(host_irq, vcpu->vcpu_id, guest_irq,
vcpu_info.vector, vcpu_info.pi_desc_addr, true);
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);
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);
}