On 2015/12/22 14:59, Wu, Feng wrote:
-----Original Message-----
From: Yang Zhang [mailto:yang.zhang.wz@xxxxxxxxx]
Sent: Tuesday, December 22, 2015 2:49 PM
To: Wu, Feng <feng.wu@xxxxxxxxx>; pbonzini@xxxxxxxxxx;
rkrcmar@xxxxxxxxxx
Cc: kvm@xxxxxxxxxxxxxxx; linux-kernel@xxxxxxxxxxxxxxx; Jiang Liu
(jiang.liu@xxxxxxxxxxxxxxx) <jiang.liu@xxxxxxxxxxxxxxx>
Subject: Re: [PATCH v2 1/2] KVM: x86: Use vector-hashing to deliver lowest-
priority interrupts
On 2015/12/16 9:37, 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>
---
arch/x86/kvm/irq_comm.c | 27 ++++++++++++++++++-----
arch/x86/kvm/lapic.c | 57
++++++++++++++++++++++++++++++++++++++++---------
arch/x86/kvm/lapic.h | 2 ++
arch/x86/kvm/x86.c | 9 ++++++++
arch/x86/kvm/x86.h | 1 +
5 files changed, 81 insertions(+), 15 deletions(-)
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)
{
@@ -731,17 +747,38 @@ 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)) {
- 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)
- l = i;
+ 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)
+ l = i;
+ }
+ bitmap = (l >= 0) ? 1 << l : 0;
+ } else {
+ int idx = 0;
+ unsigned int dest_vcpus = 0;
+
+ for_each_set_bit(i, &bitmap, 16) {
+ if (!dst[i]
&& !kvm_lapic_enabled(dst[i]->vcpu)) {
It should be or(||) not and (&&).
Oh, you are right! My negligence! Thanks for pointing this out, Yang!
btw, i think the kvm_lapic_enabled check is wrong here? Why need it here?
If the lapic is not enabled, I think we cannot recognize it as a candidate, can
we?
Maybe Radim can confirm this, Radim, what is your option?
Lapic can be disable by hw or sw. Here we only need to check the hw is
enough which is already covered while injecting the interrupt into
guest. I remember we(Glab, Macelo and me) have discussed it several ago,
but i cannot find the mail thread.
But if the lapic is disabled by software, we cannot still inject interrupts to
it, can we?
Yes, We cannot inject the normal interrupt. But this already covered by
current logic and add a check here seems meaningless. Conversely, it may
do bad thing..
--
best regards
yang
--
To unsubscribe from this list: send the line "unsubscribe kvm" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
