Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752694AbbKIDDq (ORCPT ); Sun, 8 Nov 2015 22:03:46 -0500 Received: from mga09.intel.com ([134.134.136.24]:52897 "EHLO mga09.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752478AbbKIDDm (ORCPT ); Sun, 8 Nov 2015 22:03:42 -0500 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.20,264,1444719600"; d="scan'208";a="831217035" From: Feng Wu To: pbonzini@redhat.com Cc: kvm@vger.kernel.org, linux-kernel@vger.kernel.org, Feng Wu Subject: [PATCH] KVM: x86: Add lowest-priority support for vt-d posted-interrupts Date: Mon, 9 Nov 2015 10:46:48 +0800 Message-Id: <1447037208-75615-1-git-send-email-feng.wu@intel.com> X-Mailer: git-send-email 2.1.0 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 6054 Lines: 208 Use vector-hashing to handle lowest-priority interrupts for posted-interrupts. As an example, modern Intel CPUs use this method to handle lowest-priority interrupts. Signed-off-by: Feng Wu --- arch/x86/include/asm/kvm_host.h | 2 ++ arch/x86/kvm/irq_comm.c | 52 +++++++++++++++++++++++++++++++++++++ arch/x86/kvm/lapic.c | 57 +++++++++++++++++++++++++++++++++++++++++ arch/x86/kvm/lapic.h | 2 ++ arch/x86/kvm/vmx.c | 14 ++++++++-- 5 files changed, 125 insertions(+), 2 deletions(-) diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h index 9265196..e225106 100644 --- a/arch/x86/include/asm/kvm_host.h +++ b/arch/x86/include/asm/kvm_host.h @@ -1258,6 +1258,8 @@ bool kvm_vcpu_is_bsp(struct kvm_vcpu *vcpu); bool kvm_intr_is_single_vcpu(struct kvm *kvm, struct kvm_lapic_irq *irq, struct kvm_vcpu **dest_vcpu); +struct kvm_vcpu *kvm_intr_vector_hashing_dest(struct kvm *kvm, + struct kvm_lapic_irq *irq); void kvm_set_msi_irq(struct kvm_kernel_irq_routing_entry *e, struct kvm_lapic_irq *irq); diff --git a/arch/x86/kvm/irq_comm.c b/arch/x86/kvm/irq_comm.c index 84b96d3..8156e45 100644 --- a/arch/x86/kvm/irq_comm.c +++ b/arch/x86/kvm/irq_comm.c @@ -266,6 +266,58 @@ out: return r; } +/* + * This routine handles lowest-priority interrupts using vector-hashing + * mechanism. As an example, modern Intel CPUs use this method to handle + * lowest-priority interrupts. + * + * Here is the details about the vector-hashing mechanism: + * 1. For lowest-priority interrupts, store all the possible destination + * vCPUs in an array. + * 2. Use "guest vector % max number of destination vCPUs" to find the right + * destination vCPU in the array for the lowest-priority interrupt. + */ +struct kvm_vcpu *kvm_intr_vector_hashing_dest(struct kvm *kvm, + struct kvm_lapic_irq *irq) + +{ + unsigned long dest_vcpu_bitmap[BITS_TO_LONGS(KVM_MAX_VCPUS)]; + unsigned int dest_vcpus = 0; + struct kvm_vcpu *vcpu; + unsigned int i, mod, idx = 0; + + vcpu = kvm_intr_vector_hashing_dest_fast(kvm, irq); + if (vcpu) + return vcpu; + + memset(dest_vcpu_bitmap, 0, sizeof(dest_vcpu_bitmap)); + + kvm_for_each_vcpu(i, vcpu, kvm) { + if (!kvm_apic_present(vcpu)) + continue; + + if (!kvm_apic_match_dest(vcpu, NULL, irq->shorthand, + irq->dest_id, irq->dest_mode)) + continue; + + __set_bit(vcpu->vcpu_id, dest_vcpu_bitmap); + dest_vcpus++; + } + + if (dest_vcpus == 0) + return NULL; + + mod = irq->vector % dest_vcpus; + + for (i = 0; i <= mod; i++) { + idx = find_next_bit(dest_vcpu_bitmap, KVM_MAX_VCPUS, idx) + 1; + BUG_ON(idx >= KVM_MAX_VCPUS); + } + + return kvm_get_vcpu(kvm, idx - 1); +} +EXPORT_SYMBOL_GPL(kvm_intr_vector_hashing_dest); + bool kvm_intr_is_single_vcpu(struct kvm *kvm, struct kvm_lapic_irq *irq, struct kvm_vcpu **dest_vcpu) { diff --git a/arch/x86/kvm/lapic.c b/arch/x86/kvm/lapic.c index ecd4ea1..4937aa4 100644 --- a/arch/x86/kvm/lapic.c +++ b/arch/x86/kvm/lapic.c @@ -816,6 +816,63 @@ out: return ret; } +struct kvm_vcpu *kvm_intr_vector_hashing_dest_fast(struct kvm *kvm, + struct kvm_lapic_irq *irq) +{ + struct kvm_apic_map *map; + struct kvm_vcpu *vcpu = NULL; + + if (irq->shorthand) + return NULL; + + rcu_read_lock(); + map = rcu_dereference(kvm->arch.apic_map); + + if (!map) + goto out; + + if ((irq->dest_mode != APIC_DEST_PHYSICAL) && + kvm_lowest_prio_delivery(irq)) { + u16 cid; + int i, idx = 0; + unsigned long bitmap = 1; + unsigned int mod, dest_vcpus = 0; + struct kvm_lapic **dst = NULL; + + + if (!kvm_apic_logical_map_valid(map)) + goto out; + + apic_logical_id(map, irq->dest_id, &cid, (u16 *)&bitmap); + + if (cid >= ARRAY_SIZE(map->logical_map)) + goto out; + + dst = map->logical_map[cid]; + + for_each_set_bit(i, &bitmap, 16) { + if (!dst[i]) + continue; + + dest_vcpus++; + } + + mod = irq->vector % dest_vcpus; + + for (i = 0; i <= mod; i++) { + idx = find_next_bit(&bitmap, KVM_MAX_VCPUS, idx) + 1; + BUG_ON(idx >= KVM_MAX_VCPUS); + } + + if (kvm_apic_present(dst[idx-1]->vcpu)) + vcpu = dst[idx-1]->vcpu; + } + +out: + rcu_read_unlock(); + return vcpu; +} + /* * Add a pending IRQ into lapic. * Return 1 if successfully added and 0 if discarded. diff --git a/arch/x86/kvm/lapic.h b/arch/x86/kvm/lapic.h index fde8e35d..a6a775d 100644 --- a/arch/x86/kvm/lapic.h +++ b/arch/x86/kvm/lapic.h @@ -170,4 +170,6 @@ 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); +struct kvm_vcpu *kvm_intr_vector_hashing_dest_fast(struct kvm *kvm, + struct kvm_lapic_irq *irq); #endif diff --git a/arch/x86/kvm/vmx.c b/arch/x86/kvm/vmx.c index 5eb56ed..57f71ee 100644 --- a/arch/x86/kvm/vmx.c +++ b/arch/x86/kvm/vmx.c @@ -159,6 +159,9 @@ static int ple_window_actual_max = KVM_VMX_DEFAULT_PLE_WINDOW_MAX; static int ple_window_max = KVM_VMX_DEFAULT_PLE_WINDOW_MAX; module_param(ple_window_max, int, S_IRUGO); +static bool __read_mostly enable_pi_vector_hashing = 1; +module_param(enable_pi_vector_hashing, bool, S_IRUGO); + extern const ulong vmx_return; #define NR_AUTOLOAD_MSRS 8 @@ -10702,8 +10705,15 @@ static int vmx_update_pi_irte(struct kvm *kvm, unsigned int host_irq, */ kvm_set_msi_irq(e, &irq); - if (!kvm_intr_is_single_vcpu(kvm, &irq, &vcpu)) - continue; + if (!kvm_intr_is_single_vcpu(kvm, &irq, &vcpu)) { + if ((!enable_pi_vector_hashing || + irq.delivery_mode != APIC_DM_LOWEST)) + continue; + + vcpu = kvm_intr_vector_hashing_dest(kvm, &irq); + if (!vcpu) + continue; + } vcpu_info.pi_desc_addr = __pa(vcpu_to_pi_desc(vcpu)); vcpu_info.vector = irq.vector; -- 2.1.0 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/