This patch defines a new interface kvm_find_dest_vcpu for VT-d PI, which can returns the destination vCPU of the interrupt for guests.
Since VT-d PI cannot handle broadcast/multicast interrupt, Here we only handle Fixed and Lowest priority interrupts. The current method of handling guest lowest priority interrtups is to use a counter 'apic_arb_prio' for each vCPU, we choose the vCPU with smallest 'apic_arb_prio' and then increase it by 1. However, for VT-d PI, we cannot re-use this, since we no longer have control to 'apic_arb_prio' with posted interrupt direct delivery by Hardware. Here, we introduce a similar way with 'apic_arb_prio' to handle guest lowest priority interrtups when VT-d PI is used. Here is the ideas: - Each vCPU has a counter 'round_robin_counter'. - When guests sets an interrupts to lowest priority, we choose the vCPU with smallest 'round_robin_counter' as the destination, then increase it. Signed-off-by: Feng Wu <feng...@intel.com> --- arch/x86/include/asm/kvm_host.h | 4 +++ virt/kvm/irq_comm.c | 41 +++++++++++++++++++++++++++++++++++++++ 2 files changed, 45 insertions(+), 0 deletions(-) diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h index 6ed0c30..7a41808 100644 --- a/arch/x86/include/asm/kvm_host.h +++ b/arch/x86/include/asm/kvm_host.h @@ -358,6 +358,7 @@ struct kvm_vcpu_arch { struct kvm_lapic *apic; /* kernel irqchip context */ unsigned long apic_attention; int32_t apic_arb_prio; + int32_t round_robin_counter; int mp_state; u64 ia32_misc_enable_msr; bool tpr_access_reporting; @@ -1093,4 +1094,7 @@ int kvm_pmu_read_pmc(struct kvm_vcpu *vcpu, unsigned pmc, u64 *data); void kvm_handle_pmu_event(struct kvm_vcpu *vcpu); void kvm_deliver_pmi(struct kvm_vcpu *vcpu); +bool kvm_find_dest_vcpu(struct kvm *kvm, struct kvm_lapic_irq *irq, + struct kvm_vcpu **dest_vcpu); + #endif /* _ASM_X86_KVM_HOST_H */ diff --git a/virt/kvm/irq_comm.c b/virt/kvm/irq_comm.c index 963b899..f3c5d69 100644 --- a/virt/kvm/irq_comm.c +++ b/virt/kvm/irq_comm.c @@ -317,6 +317,47 @@ out: return r; } +int kvm_compare_rr_counter(struct kvm_vcpu *vcpu1, struct kvm_vcpu *vcpu2) +{ + return vcpu1->arch.round_robin_counter - + vcpu2->arch.round_robin_counter; +} + +bool kvm_find_dest_vcpu(struct kvm *kvm, struct kvm_lapic_irq *irq, + struct kvm_vcpu **dest_vcpu) +{ + int i, r = 0; + struct kvm_vcpu *vcpu, *dest = NULL; + + 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; + + if (!kvm_is_dm_lowest_prio(irq)) { + r++; + *dest_vcpu = vcpu; + } else if (kvm_lapic_enabled(vcpu)) { + if (!dest) + dest = vcpu; + else if (kvm_compare_rr_counter(vcpu, dest) < 0) + dest = vcpu; + } + } + + if (dest) { + dest->arch.round_robin_counter++; + *dest_vcpu = dest; + return true; + } else if (r == 1) + return true; + + return false; +} + #define IOAPIC_ROUTING_ENTRY(irq) \ { .gsi = irq, .type = KVM_IRQ_ROUTING_IRQCHIP, \ .u.irqchip = { .irqchip = KVM_IRQCHIP_IOAPIC, .pin = (irq) } } -- 1.7.1 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/