> -----Original Message----- > From: linux-kernel-owner@xxxxxxxxxxxxxxx [mailto:linux-kernel- > owner@xxxxxxxxxxxxxxx] On Behalf Of Yang Zhang > Sent: Monday, December 21, 2015 10:06 AM > To: Wu, Feng <feng.wu@xxxxxxxxx>; pbonzini@xxxxxxxxxx; > rkrcmar@xxxxxxxxxx > Cc: kvm@xxxxxxxxxxxxxxx; linux-kernel@xxxxxxxxxxxxxxx > Subject: Re: [PATCH v2 1/2] KVM: x86: Use vector-hashing to deliver lowest- > priority interrupts > > On 2015/12/21 9:50, Wu, Feng wrote: > > > > > >> -----Original Message----- > >> From: Yang Zhang [mailto:yang.zhang.wz@xxxxxxxxx] > >> Sent: Monday, December 21, 2015 9:46 AM > >> To: Wu, Feng <feng.wu@xxxxxxxxx>; pbonzini@xxxxxxxxxx; > >> rkrcmar@xxxxxxxxxx > >> Cc: kvm@xxxxxxxxxxxxxxx; linux-kernel@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? 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
