KVM: change the way how lowest priority vcpu is calculated

The new way does not require additional loop over vcpus to calculate
the one with lowest priority as one is chosen during delivery bitmap
construction.

Signed-off-by: Gleb Natapov <gleb@redhat.com>
Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com>

1 files changed, 11 insertions, 8 deletions

diff --git a/virt/kvm/irq_comm.c b/virt/kvm/irq_comm.c
index e43701c0a5c4..f5e059b67cd4 100644
--- a/virt/kvm/irq_comm.c
+++ b/virt/kvm/irq_comm.c
@@ -47,7 +47,7 @@ void kvm_get_intr_delivery_bitmask(struct kvm *kvm, struct kvm_lapic *src,
                 int dest_id, int dest_mode, bool low_prio, int short_hand,
                 unsigned long *deliver_bitmask)
 {
-        int i;
+        int i, lowest = -1;
         struct kvm_vcpu *vcpu;
 
         if (dest_mode == 0 && dest_id == 0xff && low_prio)
@@ -64,15 +64,18 @@ void kvm_get_intr_delivery_bitmask(struct kvm *kvm, struct kvm_lapic *src,
                                         dest_mode))
                         continue;
 
-                __set_bit(i, deliver_bitmask);
+                if (!low_prio) {
+                        __set_bit(i, deliver_bitmask);
+                } else {
+                        if (lowest < 0)
+                                lowest = i;
+                        if (kvm_apic_compare_prio(vcpu, kvm->vcpus[lowest]) < 0)
+                                lowest = i;
+                }
         }
 
-        if (low_prio) {
-                vcpu = kvm_get_lowest_prio_vcpu(kvm, 0, deliver_bitmask);
-                bitmap_zero(deliver_bitmask, KVM_MAX_VCPUS);
-                if (vcpu)
-                        __set_bit(vcpu->vcpu_id, deliver_bitmask);
-        }
+        if (lowest != -1)
+                __set_bit(lowest, deliver_bitmask);
 }
 
 static int kvm_set_msi(struct kvm_kernel_irq_routing_entry *e,