From 6228a0da805792c2f25b32e9b926d0810a6648ab Mon Sep 17 00:00:00 2001 From: Feng Wu Date: Mon, 25 Jan 2016 16:53:34 +0800 Subject: [PATCH] KVM: x86: Add lowest-priority support for vt-d posted-interrupts MIME-Version: 1.0 Content-Type: text/plain; charset=utf8 Content-Transfer-Encoding: 8bit Use vector-hashing to deliver lowest-priority interrupts for VT-d posted-interrupts. This patch extends kvm_intr_is_single_vcpu() to support lowest-priority handling. Signed-off-by: Feng Wu Reviewed-by: Radim Krčmář Signed-off-by: Paolo Bonzini --- arch/x86/kvm/lapic.c | 56 ++++++++++++++++++++++++++++++++++++++------ 1 file changed, 49 insertions(+), 7 deletions(-) diff --git a/arch/x86/kvm/lapic.c b/arch/x86/kvm/lapic.c index 1a4ca1d05fe9..1520d1acd0ad 100644 --- a/arch/x86/kvm/lapic.c +++ b/arch/x86/kvm/lapic.c @@ -798,6 +798,20 @@ bool kvm_irq_delivery_to_apic_fast(struct kvm *kvm, struct kvm_lapic *src, return ret; } +/* + * This routine tries to handler interrupts in posted mode, here is how + * it deals with different cases: + * - For single-destination interrupts, handle it in posted mode + * - Else if vector hashing is enabled and it is a lowest-priority + * interrupt, handle it in posted mode and use the following mechanism + * to find the destinaiton vCPU. + * 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. + * - Otherwise, use remapped mode to inject the interrupt. + */ bool kvm_intr_is_single_vcpu_fast(struct kvm *kvm, struct kvm_lapic_irq *irq, struct kvm_vcpu **dest_vcpu) { @@ -839,16 +853,44 @@ bool kvm_intr_is_single_vcpu_fast(struct kvm *kvm, struct kvm_lapic_irq *irq, if (cid >= ARRAY_SIZE(map->logical_map)) goto out; - for_each_set_bit(i, &bitmap, 16) { - dst = map->logical_map[cid][i]; - if (++r == 2) + if (kvm_vector_hashing_enabled() && + kvm_lowest_prio_delivery(irq)) { + int idx; + unsigned int dest_vcpus; + + dest_vcpus = hweight16(bitmap); + if (dest_vcpus == 0) goto out; - } - if (dst && kvm_apic_present(dst->vcpu)) + idx = kvm_vector_to_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 + */ + dst = map->logical_map[cid][idx]; + if (!dst && !kvm->arch.disabled_lapic_found) { + kvm->arch.disabled_lapic_found = true; + printk(KERN_INFO + "Disabled LAPIC found during irq injection\n"); + goto out; + } + *dest_vcpu = dst->vcpu; - else - goto out; + } else { + for_each_set_bit(i, &bitmap, 16) { + dst = map->logical_map[cid][i]; + if (++r == 2) + goto out; + } + + if (dst && kvm_apic_present(dst->vcpu)) + *dest_vcpu = dst->vcpu; + else + goto out; + } } ret = true; -- 2.45.2