From e3c89f5dd11df791b55b320c3869a97414ef5d06 Mon Sep 17 00:00:00 2001 From: Yi Wang Date: Mon, 6 May 2024 18:17:50 +0800 Subject: [PATCH] KVM: x86: Don't re-setup empty IRQ routing when KVM_CAP_SPLIT_IRQCHIP Now that KVM sets up empty IRQ routing during VM creation, don't recreate empty routing during KVM_CAP_SPLIT_IRQCHIP. Setting IRQ routes during KVM_CAP_SPLIT_IRQCHIP can result in 20+ milliseconds of delay due to the synchronize_srcu_expedited() call in kvm_set_irq_routing(). Note, the empty routing is guaranteed to be intact as KVM x86 only allows changing the IRQ routing after an in-kernel IRQCHIP has been created, and KVM_CAP_SPLIT_IRQCHIP is disallowed after creating an IRQCHIP. Signed-off-by: Yi Wang Link: https://lore.kernel.org/r/20240506101751.3145407-3-foxywang@tencent.com [sean: massage changelog, remove unused empty_routing array] Signed-off-by: Sean Christopherson --- arch/x86/kvm/irq.h | 1 - arch/x86/kvm/irq_comm.c | 7 ------- arch/x86/kvm/x86.c | 3 --- 3 files changed, 11 deletions(-) diff --git a/arch/x86/kvm/irq.h b/arch/x86/kvm/irq.h index c2d7cfe82d00..76d46b2f41dd 100644 --- a/arch/x86/kvm/irq.h +++ b/arch/x86/kvm/irq.h @@ -106,7 +106,6 @@ void __kvm_migrate_timers(struct kvm_vcpu *vcpu); int apic_has_pending_timer(struct kvm_vcpu *vcpu); int kvm_setup_default_irq_routing(struct kvm *kvm); -int kvm_setup_empty_irq_routing(struct kvm *kvm); int kvm_irq_delivery_to_apic(struct kvm *kvm, struct kvm_lapic *src, struct kvm_lapic_irq *irq, struct dest_map *dest_map); diff --git a/arch/x86/kvm/irq_comm.c b/arch/x86/kvm/irq_comm.c index 68f3f6c26046..8136695f7b96 100644 --- a/arch/x86/kvm/irq_comm.c +++ b/arch/x86/kvm/irq_comm.c @@ -395,13 +395,6 @@ int kvm_setup_default_irq_routing(struct kvm *kvm) ARRAY_SIZE(default_routing), 0); } -static const struct kvm_irq_routing_entry empty_routing[] = {}; - -int kvm_setup_empty_irq_routing(struct kvm *kvm) -{ - return kvm_set_irq_routing(kvm, empty_routing, 0, 0); -} - void kvm_arch_post_irq_routing_update(struct kvm *kvm) { if (!irqchip_split(kvm)) diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c index 082ac6d95a3a..a5c8caed76b1 100644 --- a/arch/x86/kvm/x86.c +++ b/arch/x86/kvm/x86.c @@ -6552,9 +6552,6 @@ int kvm_vm_ioctl_enable_cap(struct kvm *kvm, goto split_irqchip_unlock; if (kvm->created_vcpus) goto split_irqchip_unlock; - r = kvm_setup_empty_irq_routing(kvm); - if (r) - goto split_irqchip_unlock; /* Pairs with irqchip_in_kernel. */ smp_wmb(); kvm->arch.irqchip_mode = KVM_IRQCHIP_SPLIT; -- 2.50.1