On 2016/1/21 13:33, Wu, Feng wrote:
-----Original Message-----
From: linux-kernel-owner@xxxxxxxxxxxxxxx [mailto:linux-kernel-
owner@xxxxxxxxxxxxxxx] On Behalf Of Yang Zhang
Sent: Thursday, January 21, 2016 1:24 PM
To: Wu, Feng <feng.wu@xxxxxxxxx>; pbonzini@xxxxxxxxxx;
rkrcmar@xxxxxxxxxx
Cc: linux-kernel@xxxxxxxxxxxxxxx; kvm@xxxxxxxxxxxxxxx
Subject: Re: [PATCH v3 2/4] KVM: x86: Use vector-hashing to deliver lowest-
priority interrupts
On 2016/1/20 9:42, Feng Wu wrote:
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@xxxxxxxxx>
---
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 +743,51 @@ bool kvm_irq_delivery_to_apic_fast(struct kvm
*kvm, struct kvm_lapic *src,
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 = 0;
+ unsigned int dest_vcpus = 0;
+
+ dest_vcpus = hweight16(bitmap);
+ if (dest_vcpus == 0)
+ goto out;
+
+ idx = kvm_vector_2_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-1] &&
+ (kvm->arch.disabled_lapic_found == 0)) {
+ kvm->arch.disabled_lapic_found = 1;
+ printk(KERN_ERR
+ "Disabled LAPIC found during irq
injection\n");
+ goto out;
What does "goto out" mean? Inject successfully or fail? According the
value of ret which is set to ture here, it means inject successfully but
i = -1.
Oh, I didn't notice 'ret' is initialized to true, I thought it was initialized
to false like another function, I should add a "ret = false' here. We should
failed to inject the interrupt since hardware disabled LAPIC is found.
I remember we have discussed that even the LAPIC is software disabled,
it still can respond to some interrupts like INIT, NMI, SMI, and SIPI
messages. Isn't current logic still problematically?
--
best regards
yang
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