KVM: x86: Use vector-hashing to deliver lowest-priority interrupts
Use vector-hashing to deliver lowest-priority interrupts, As an
example, modern Intel CPUs in server platform use this method to
handle lowest-priority interrupts.
Signed-off-by: Feng Wu <feng.wu@intel.com>
Reviewed-by: Radim Krčmář <rkrcmar@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
diff --git a/arch/x86/kvm/lapic.c b/arch/x86/kvm/lapic.c
index 36591fa..1a4ca1d 100644
--- a/arch/x86/kvm/lapic.c
+++ b/arch/x86/kvm/lapic.c
@@ -675,6 +675,22 @@
}
}
+int kvm_vector_to_index(u32 vector, u32 dest_vcpus,
+ const unsigned long *bitmap, u32 bitmap_size)
+{
+ u32 mod;
+ int i, idx = -1;
+
+ mod = vector % dest_vcpus;
+
+ for (i = 0; i <= mod; i++) {
+ idx = find_next_bit(bitmap, bitmap_size, idx + 1);
+ BUG_ON(idx == bitmap_size);
+ }
+
+ return idx;
+}
+
bool kvm_irq_delivery_to_apic_fast(struct kvm *kvm, struct kvm_lapic *src,
struct kvm_lapic_irq *irq, int *r, unsigned long *dest_map)
{
@@ -727,21 +743,49 @@
dst = map->logical_map[cid];
- if (kvm_lowest_prio_delivery(irq)) {
+ if (!kvm_lowest_prio_delivery(irq))
+ goto set_irq;
+
+ if (!kvm_vector_hashing_enabled()) {
int l = -1;
for_each_set_bit(i, &bitmap, 16) {
if (!dst[i])
continue;
if (l < 0)
l = i;
- else if (kvm_apic_compare_prio(dst[i]->vcpu, dst[l]->vcpu) < 0)
+ else if (kvm_apic_compare_prio(dst[i]->vcpu,
+ dst[l]->vcpu) < 0)
l = i;
}
-
bitmap = (l >= 0) ? 1 << l : 0;
+ } else {
+ int idx;
+ unsigned int dest_vcpus;
+
+ dest_vcpus = hweight16(bitmap);
+ if (dest_vcpus == 0)
+ goto out;
+
+ idx = kvm_vector_to_index(irq->vector,
+ dest_vcpus, &bitmap, 16);
+
+ /*
+ * We may find a hardware disabled LAPIC here, if that
+ * is the case, print out a error message once for each
+ * guest and return.
+ */
+ if (!dst[idx] && !kvm->arch.disabled_lapic_found) {
+ kvm->arch.disabled_lapic_found = true;
+ printk(KERN_INFO
+ "Disabled LAPIC found during irq injection\n");
+ goto out;
+ }
+
+ bitmap = (idx >= 0) ? 1 << idx : 0;
}
}
+set_irq:
for_each_set_bit(i, &bitmap, 16) {
if (!dst[i])
continue;
