Re: [PATCH v4 19/26] KVM: arm/arm64: GICv4: Add doorbell interrupt handling

Christoffer Dall
2017-10-26T15:25:25Z

On Fri, Oct 06, 2017 at 04:33:54PM +0100, Marc Zyngier wrote:
> When a vPE is not running, a VLPI being made pending results in a
> doorbell interrupt being delivered. Let's handle this interrupt
> and update the pending_last flag that indicates that VLPIs are
> pending. The corresponding vcpu is also kicked into action.
>
> Special care is taken care of not allowing the doorbell to be
> enabled at request time (this is controlled separately), and

super nit: this first sentence is pretty hard to understand...

> to make the disabling on the interrupt non-lazy.
>
> Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>
> ---
> virt/kvm/arm/vgic/vgic-v4.c | 48 +++++++++++++++++++++++++++++++++++++++++++++
> 1 file changed, 48 insertions(+)
>
> diff --git a/virt/kvm/arm/vgic/vgic-v4.c b/virt/kvm/arm/vgic/vgic-v4.c
> index b79a0450bb1c..2c250ee37878 100644
> --- a/virt/kvm/arm/vgic/vgic-v4.c
> +++ b/virt/kvm/arm/vgic/vgic-v4.c
> @@ -16,11 +16,23 @@
> */
>
> #include <linux/interrupt.h>
> +#include <linux/irq.h>
> #include <linux/irqdomain.h>
> #include <linux/kvm_host.h>
>
> #include "vgic.h"
>
> +static irqreturn_t vgic_v4_doorbell_handler(int irq, void *info)
> +{
> + struct kvm_vcpu *vcpu = info;
> +
> + vcpu->arch.vgic_cpu.vgic_v3.its_vpe.pending_last = true;
> + kvm_make_request(KVM_REQ_IRQ_PENDING, vcpu);
> + kvm_vcpu_kick(vcpu);
> +
> + return IRQ_HANDLED;
> +}
> +
> /**
> * vgic_v4_init - Initialize the GICv4 data structures
> * @kvm: Pointer to the VM being initialized
> @@ -60,6 +72,33 @@ int vgic_v4_init(struct kvm *kvm)
> return ret;
> }
>
> + 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) {
> + kvm_err("failed to allocate vcpu IRQ%d\n", irq);
> + /*
> + * Trick: adjust the number of vpes so we know
> + * how many to nuke on teardown...
> + */
> + dist->its_vm.nr_vpes = i;
> + break;
> + }
> + }
> +
> + if (ret)
> + vgic_v4_teardown(kvm);
> +
> return ret;
> }
>
> @@ -72,10 +111,19 @@ int vgic_v4_init(struct kvm *kvm)
> void vgic_v4_teardown(struct kvm *kvm)
> {
> struct its_vm *its_vm = &kvm->arch.vgic.its_vm;
> + int i;
>
> if (!its_vm->vpes)
> return;
>
> + for (i = 0; i < its_vm->nr_vpes; i++) {
> + struct kvm_vcpu *vcpu = kvm_get_vcpu(kvm, i);
> + 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);
> kfree(its_vm->vpes);
> its_vm->nr_vpes = 0;
> --
> 2.14.1
>