Message ID | 20170731172637.29355-53-marc.zyngier@arm.com (mailing list archive) |
---|---|
State | New, archived |
Headers | show |
On Mon, Jul 31, 2017 at 06:26:30PM +0100, Marc Zyngier wrote: > The doorbell interrupt is only useful if the vcpu is blocked on WFI. > In all other cases, recieving a doorbell interrupt is just a waste > of cycles. > > So let's only enable the doorbell if a vcpu is getting blocked, > and disable it when it is unblocked. This is very similar to > what we're doing for the background timer. > > Signed-off-by: Marc Zyngier <marc.zyngier@arm.com> > --- > include/kvm/arm_vgic.h | 3 +++ > virt/kvm/arm/arm.c | 2 ++ > virt/kvm/arm/vgic/vgic-v4.c | 32 +++++++++++++++++++++++++++++++- > 3 files changed, 36 insertions(+), 1 deletion(-) > > diff --git a/include/kvm/arm_vgic.h b/include/kvm/arm_vgic.h > index 050f78d4fb42..7b1cc7ff5b42 100644 > --- a/include/kvm/arm_vgic.h > +++ b/include/kvm/arm_vgic.h > @@ -375,4 +375,7 @@ int kvm_vgic_v4_set_forwarding(struct kvm *kvm, int irq, > int kvm_vgic_v4_unset_forwarding(struct kvm *kvm, int irq, > struct kvm_kernel_irq_routing_entry *irq_entry); > > +void kvm_vgic_v4_enable_doorbell(struct kvm_vcpu *vcpu); > +void kvm_vgic_v4_disable_doorbell(struct kvm_vcpu *vcpu); > + > #endif /* __KVM_ARM_VGIC_H */ > diff --git a/virt/kvm/arm/arm.c b/virt/kvm/arm/arm.c > index 6803ea27c47d..5dbc8dc8fbf4 100644 > --- a/virt/kvm/arm/arm.c > +++ b/virt/kvm/arm/arm.c > @@ -316,11 +316,13 @@ int kvm_cpu_has_pending_timer(struct kvm_vcpu *vcpu) > void kvm_arch_vcpu_blocking(struct kvm_vcpu *vcpu) > { > kvm_timer_schedule(vcpu); > + kvm_vgic_v4_enable_doorbell(vcpu); > } > > void kvm_arch_vcpu_unblocking(struct kvm_vcpu *vcpu) > { > kvm_timer_unschedule(vcpu); > + kvm_vgic_v4_disable_doorbell(vcpu); > } > > int kvm_arch_vcpu_init(struct kvm_vcpu *vcpu) > diff --git a/virt/kvm/arm/vgic/vgic-v4.c b/virt/kvm/arm/vgic/vgic-v4.c > index 6af3cde6d7d4..50721c4e3da5 100644 > --- a/virt/kvm/arm/vgic/vgic-v4.c > +++ b/virt/kvm/arm/vgic/vgic-v4.c > @@ -16,6 +16,7 @@ > */ > > #include <linux/interrupt.h> > +#include <linux/irq.h> > #include <linux/irqdomain.h> > #include <linux/kvm_host.h> > > @@ -73,6 +74,14 @@ int vgic_v4_init(struct kvm *kvm) > kvm_for_each_vcpu(i, vcpu, kvm) { > int irq = dist->its_vm.vpes[i]->irq; > > + /* > + * Don't automatically enable the doorbell, as we're > + * flipping it back and forth when the vcpu gets > + * blocked. Also disable the lazy disabling, as the > + * doorbell could kick us out of the guest too > + * early... > + */ > + irq_set_status_flags(irq, IRQ_NOAUTOEN | IRQ_DISABLE_UNLAZY); > ret = request_irq(irq, vgic_v4_doorbell_handler, > 0, "vcpu", vcpu); > if (ret) { > @@ -98,7 +107,10 @@ void vgic_v4_teardown(struct kvm *kvm) > > for (i = 0; i < its_vm->nr_vpes; i++) { > struct kvm_vcpu *vcpu = kvm_get_vcpu(kvm, i); > - free_irq(its_vm->vpes[i]->irq, vcpu); > + int irq = its_vm->vpes[i]->irq; > + > + irq_clear_status_flags(irq, IRQ_NOAUTOEN | IRQ_DISABLE_UNLAZY); > + free_irq(irq, vcpu); > } > > its_free_vcpu_irqs(its_vm); > @@ -211,3 +223,21 @@ int kvm_vgic_v4_unset_forwarding(struct kvm *kvm, int virq, > mutex_unlock(&its->its_lock); > return ret; > } > + > +void kvm_vgic_v4_enable_doorbell(struct kvm_vcpu *vcpu) > +{ > + if (vgic_is_v4_capable(vcpu->kvm)) { > + int irq = vcpu->arch.vgic_cpu.vgic_v3.its_vpe.irq; > + if (irq) > + enable_irq(irq); > + } > +} > + > +void kvm_vgic_v4_disable_doorbell(struct kvm_vcpu *vcpu) > +{ > + if (vgic_is_v4_capable(vcpu->kvm)) { > + int irq = vcpu->arch.vgic_cpu.vgic_v3.its_vpe.irq; > + if (irq) > + disable_irq(irq); > + } > +} > -- > 2.11.0 > Reviewed-by: Christoffer Dall <cdall@linaro.org>
diff --git a/include/kvm/arm_vgic.h b/include/kvm/arm_vgic.h index 050f78d4fb42..7b1cc7ff5b42 100644 --- a/include/kvm/arm_vgic.h +++ b/include/kvm/arm_vgic.h @@ -375,4 +375,7 @@ int kvm_vgic_v4_set_forwarding(struct kvm *kvm, int irq, int kvm_vgic_v4_unset_forwarding(struct kvm *kvm, int irq, struct kvm_kernel_irq_routing_entry *irq_entry); +void kvm_vgic_v4_enable_doorbell(struct kvm_vcpu *vcpu); +void kvm_vgic_v4_disable_doorbell(struct kvm_vcpu *vcpu); + #endif /* __KVM_ARM_VGIC_H */ diff --git a/virt/kvm/arm/arm.c b/virt/kvm/arm/arm.c index 6803ea27c47d..5dbc8dc8fbf4 100644 --- a/virt/kvm/arm/arm.c +++ b/virt/kvm/arm/arm.c @@ -316,11 +316,13 @@ int kvm_cpu_has_pending_timer(struct kvm_vcpu *vcpu) void kvm_arch_vcpu_blocking(struct kvm_vcpu *vcpu) { kvm_timer_schedule(vcpu); + kvm_vgic_v4_enable_doorbell(vcpu); } void kvm_arch_vcpu_unblocking(struct kvm_vcpu *vcpu) { kvm_timer_unschedule(vcpu); + kvm_vgic_v4_disable_doorbell(vcpu); } int kvm_arch_vcpu_init(struct kvm_vcpu *vcpu) diff --git a/virt/kvm/arm/vgic/vgic-v4.c b/virt/kvm/arm/vgic/vgic-v4.c index 6af3cde6d7d4..50721c4e3da5 100644 --- a/virt/kvm/arm/vgic/vgic-v4.c +++ b/virt/kvm/arm/vgic/vgic-v4.c @@ -16,6 +16,7 @@ */ #include <linux/interrupt.h> +#include <linux/irq.h> #include <linux/irqdomain.h> #include <linux/kvm_host.h> @@ -73,6 +74,14 @@ int vgic_v4_init(struct kvm *kvm) kvm_for_each_vcpu(i, vcpu, kvm) { int irq = dist->its_vm.vpes[i]->irq; + /* + * Don't automatically enable the doorbell, as we're + * flipping it back and forth when the vcpu gets + * blocked. Also disable the lazy disabling, as the + * doorbell could kick us out of the guest too + * early... + */ + irq_set_status_flags(irq, IRQ_NOAUTOEN | IRQ_DISABLE_UNLAZY); ret = request_irq(irq, vgic_v4_doorbell_handler, 0, "vcpu", vcpu); if (ret) { @@ -98,7 +107,10 @@ void vgic_v4_teardown(struct kvm *kvm) for (i = 0; i < its_vm->nr_vpes; i++) { struct kvm_vcpu *vcpu = kvm_get_vcpu(kvm, i); - free_irq(its_vm->vpes[i]->irq, vcpu); + int irq = its_vm->vpes[i]->irq; + + irq_clear_status_flags(irq, IRQ_NOAUTOEN | IRQ_DISABLE_UNLAZY); + free_irq(irq, vcpu); } its_free_vcpu_irqs(its_vm); @@ -211,3 +223,21 @@ int kvm_vgic_v4_unset_forwarding(struct kvm *kvm, int virq, mutex_unlock(&its->its_lock); return ret; } + +void kvm_vgic_v4_enable_doorbell(struct kvm_vcpu *vcpu) +{ + if (vgic_is_v4_capable(vcpu->kvm)) { + int irq = vcpu->arch.vgic_cpu.vgic_v3.its_vpe.irq; + if (irq) + enable_irq(irq); + } +} + +void kvm_vgic_v4_disable_doorbell(struct kvm_vcpu *vcpu) +{ + if (vgic_is_v4_capable(vcpu->kvm)) { + int irq = vcpu->arch.vgic_cpu.vgic_v3.its_vpe.irq; + if (irq) + disable_irq(irq); + } +}
The doorbell interrupt is only useful if the vcpu is blocked on WFI. In all other cases, recieving a doorbell interrupt is just a waste of cycles. So let's only enable the doorbell if a vcpu is getting blocked, and disable it when it is unblocked. This is very similar to what we're doing for the background timer. Signed-off-by: Marc Zyngier <marc.zyngier@arm.com> --- include/kvm/arm_vgic.h | 3 +++ virt/kvm/arm/arm.c | 2 ++ virt/kvm/arm/vgic/vgic-v4.c | 32 +++++++++++++++++++++++++++++++- 3 files changed, 36 insertions(+), 1 deletion(-)