> -----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? Thanks, Feng -- 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
