From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1758659AbcAUFXy (ORCPT ); Thu, 21 Jan 2016 00:23:54 -0500 Received: from mail-pf0-f193.google.com ([209.85.192.193]:36101 "EHLO mail-pf0-f193.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750788AbcAUFXv (ORCPT ); Thu, 21 Jan 2016 00:23:51 -0500 Subject: Re: [PATCH v3 2/4] KVM: x86: Use vector-hashing to deliver lowest-priority interrupts To: Feng Wu , pbonzini@redhat.com, rkrcmar@redhat.com References: <1453254177-103002-1-git-send-email-feng.wu@intel.com> <1453254177-103002-3-git-send-email-feng.wu@intel.com> Cc: linux-kernel@vger.kernel.org, kvm@vger.kernel.org From: Yang Zhang Message-ID: <56A06B60.5030501@gmail.com> Date: Thu, 21 Jan 2016 13:23:44 +0800 User-Agent: Mozilla/5.0 (Windows NT 6.1; WOW64; rv:38.0) Gecko/20100101 Thunderbird/38.5.1 MIME-Version: 1.0 In-Reply-To: <1453254177-103002-3-git-send-email-feng.wu@intel.com> Content-Type: text/plain; charset=windows-1252; format=flowed Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 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 > --- > v3: > - Fix a bug for sparse topologies, in that case, vcpu_id is not equal > to the return value got by kvm_get_vcpu(). > - Remove unnecessary check in fast irq delivery patch. > - print a error message only once for each guest when we find hardware > disabled LAPIC during interrupt injection. > > arch/x86/include/asm/kvm_host.h | 2 ++ > arch/x86/kvm/irq_comm.c | 27 +++++++++++++++++---- > arch/x86/kvm/lapic.c | 52 ++++++++++++++++++++++++++++++++++++++--- > arch/x86/kvm/lapic.h | 2 ++ > arch/x86/kvm/x86.c | 9 +++++++ > arch/x86/kvm/x86.h | 1 + > 6 files changed, 85 insertions(+), 8 deletions(-) > > diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h > index 44adbb8..5054810 100644 > --- a/arch/x86/include/asm/kvm_host.h > +++ b/arch/x86/include/asm/kvm_host.h > @@ -754,6 +754,8 @@ struct kvm_arch { > > bool irqchip_split; > u8 nr_reserved_ioapic_pins; > + > + int disabled_lapic_found; > }; > > struct kvm_vm_stat { > diff --git a/arch/x86/kvm/irq_comm.c b/arch/x86/kvm/irq_comm.c > index 8fc89ef..062e907 100644 > --- a/arch/x86/kvm/irq_comm.c > +++ b/arch/x86/kvm/irq_comm.c > @@ -34,6 +34,7 @@ > #include "lapic.h" > > #include "hyperv.h" > +#include "x86.h" > > static int kvm_set_pic_irq(struct kvm_kernel_irq_routing_entry *e, > struct kvm *kvm, int irq_source_id, int level, > @@ -55,8 +56,10 @@ static int kvm_set_ioapic_irq(struct kvm_kernel_irq_routing_entry *e, > int kvm_irq_delivery_to_apic(struct kvm *kvm, struct kvm_lapic *src, > struct kvm_lapic_irq *irq, unsigned long *dest_map) > { > - int i, r = -1; > + int i, r = -1, idx = 0; > struct kvm_vcpu *vcpu, *lowest = NULL; > + unsigned long dest_vcpu_bitmap[BITS_TO_LONGS(KVM_MAX_VCPUS)]; > + unsigned int dest_vcpus = 0; > > if (irq->dest_mode == 0 && irq->dest_id == 0xff && > kvm_lowest_prio_delivery(irq)) { > @@ -67,6 +70,8 @@ int kvm_irq_delivery_to_apic(struct kvm *kvm, struct kvm_lapic *src, > if (kvm_irq_delivery_to_apic_fast(kvm, src, irq, &r, dest_map)) > return r; > > + memset(dest_vcpu_bitmap, 0, sizeof(dest_vcpu_bitmap)); > + > kvm_for_each_vcpu(i, vcpu, kvm) { > if (!kvm_apic_present(vcpu)) > continue; > @@ -80,13 +85,25 @@ int kvm_irq_delivery_to_apic(struct kvm *kvm, struct kvm_lapic *src, > r = 0; > r += kvm_apic_set_irq(vcpu, irq, dest_map); > } else if (kvm_lapic_enabled(vcpu)) { > - if (!lowest) > - lowest = vcpu; > - else if (kvm_apic_compare_prio(vcpu, lowest) < 0) > - lowest = vcpu; > + if (!kvm_vector_hashing_enabled()) { > + if (!lowest) > + lowest = vcpu; > + else if (kvm_apic_compare_prio(vcpu, lowest) < 0) > + lowest = vcpu; > + } else { > + __set_bit(i, dest_vcpu_bitmap); > + dest_vcpus++; > + } > } > } > > + if (dest_vcpus != 0) { > + idx = kvm_vector_2_index(irq->vector, dest_vcpus, > + dest_vcpu_bitmap, KVM_MAX_VCPUS); > + > + lowest = kvm_get_vcpu(kvm, idx - 1); > + } > + > if (lowest) > r = kvm_apic_set_irq(lowest, irq, dest_map); > > diff --git a/arch/x86/kvm/lapic.c b/arch/x86/kvm/lapic.c > index 36591fa..e1a449da 100644 > --- a/arch/x86/kvm/lapic.c > +++ b/arch/x86/kvm/lapic.c > @@ -675,6 +675,22 @@ bool kvm_apic_match_dest(struct kvm_vcpu *vcpu, struct kvm_lapic *source, > } > } > > +int kvm_vector_2_index(u32 vector, u32 dest_vcpus, > + const unsigned long *bitmap, u32 bitmap_size) > +{ > + u32 mod; > + int i, idx = 0; > + > + mod = vector % dest_vcpus; > + > + for (i = 0; i <= mod; i++) { > + idx = find_next_bit(bitmap, bitmap_size, idx) + 1; > + BUG_ON(idx > bitmap_size); > + } > + > + return idx; > +} > + > 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. > + } > + > + bitmap = 0; > + __set_bit(idx-1, &bitmap); We can reuse the code like: bitmap = (idx > 0) ? 1 << (idx - 1) : 0; > } > } > > +set_irq: > for_each_set_bit(i, &bitmap, 16) { > if (!dst[i]) > continue; > diff --git a/arch/x86/kvm/lapic.h b/arch/x86/kvm/lapic.h > index 41bdb35..d864601 100644 > --- a/arch/x86/kvm/lapic.h > +++ b/arch/x86/kvm/lapic.h > @@ -175,4 +175,6 @@ void wait_lapic_expire(struct kvm_vcpu *vcpu); > > bool kvm_intr_is_single_vcpu_fast(struct kvm *kvm, struct kvm_lapic_irq *irq, > struct kvm_vcpu **dest_vcpu); > +int kvm_vector_2_index(u32 vector, u32 dest_vcpus, > + const unsigned long *bitmap, u32 bitmap_size); > #endif > diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c > index 4244c2b..47daf77 100644 > --- a/arch/x86/kvm/x86.c > +++ b/arch/x86/kvm/x86.c > @@ -123,6 +123,9 @@ module_param(tsc_tolerance_ppm, uint, S_IRUGO | S_IWUSR); > unsigned int __read_mostly lapic_timer_advance_ns = 0; > module_param(lapic_timer_advance_ns, uint, S_IRUGO | S_IWUSR); > > +bool __read_mostly enable_vector_hashing = 1; > +module_param(enable_vector_hashing, bool, S_IRUGO); > + > static bool __read_mostly backwards_tsc_observed = false; > > #define KVM_NR_SHARED_MSRS 16 > @@ -8370,6 +8373,12 @@ int kvm_arch_update_irqfd_routing(struct kvm *kvm, unsigned int host_irq, > return kvm_x86_ops->update_pi_irte(kvm, host_irq, guest_irq, set); > } > > +bool kvm_vector_hashing_enabled(void) > +{ > + return enable_vector_hashing; > +} > +EXPORT_SYMBOL_GPL(kvm_vector_hashing_enabled); > + > EXPORT_TRACEPOINT_SYMBOL_GPL(kvm_exit); > EXPORT_TRACEPOINT_SYMBOL_GPL(kvm_fast_mmio); > EXPORT_TRACEPOINT_SYMBOL_GPL(kvm_inj_virq); > diff --git a/arch/x86/kvm/x86.h b/arch/x86/kvm/x86.h > index f2afa5f..04bd0f9 100644 > --- a/arch/x86/kvm/x86.h > +++ b/arch/x86/kvm/x86.h > @@ -179,6 +179,7 @@ int kvm_mtrr_set_msr(struct kvm_vcpu *vcpu, u32 msr, u64 data); > int kvm_mtrr_get_msr(struct kvm_vcpu *vcpu, u32 msr, u64 *pdata); > bool kvm_mtrr_check_gfn_range_consistency(struct kvm_vcpu *vcpu, gfn_t gfn, > int page_num); > +bool kvm_vector_hashing_enabled(void); > > #define KVM_SUPPORTED_XCR0 (XFEATURE_MASK_FP | XFEATURE_MASK_SSE \ > | XFEATURE_MASK_YMM | XFEATURE_MASK_BNDREGS \ > -- best regards yang