> -----Original Message-----
> From: Yang Zhang [mailto:yang.zhang...@gmail.com]
> Sent: Tuesday, December 22, 2015 2:49 PM
> To: Wu, Feng <feng...@intel.com>; pbonz...@redhat.com;
> rkrc...@redhat.com
> Cc: kvm@vger.kernel.org; linux-ker...@vger.kernel.org; Jiang Liu
> (jiang....@linux.intel.com) <jiang....@linux.intel.com>
> 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...@intel.com>
> >>>>> ---
> >>>>>     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?

Thanks,
Feng
--
To unsubscribe from this list: send the line "unsubscribe kvm" in
the body of a message to majord...@vger.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html

Reply via email to