Re: [PATCH 08/10] KVM: arm/arm64: vgic: Handle unshared mapped interrupts

Marc Zyngier
2017-05-25T19:10:48Z

On Wed, May 24 2017 at 10:13:21 pm BST, Eric Auger <eric.auger@redhat.com> wrote:
> Virtual interrupts directly mapped to physical interrupts require
> some special care. Their pending and active state must be observed
> at distributor level and not in the list register.
>
> Also a level sensitive interrupt's level is not toggled down by any
> maintenance IRQ handler as the EOI is not trapped.
>
> This patch adds an host_irq field in vgic_irq struct to easily
> get the irqchip state of the host irq. We also handle the
> physical IRQ case in vgic_validate_injection and add helpers to
> get the line level and active state.
>
> Signed-off-by: Eric Auger <eric.auger@redhat.com>
> ---
> include/kvm/arm_vgic.h | 4 +++-
> virt/kvm/arm/arch_timer.c | 3 ++-
> virt/kvm/arm/vgic/vgic.c | 44 ++++++++++++++++++++++++++++++++++++++------
> virt/kvm/arm/vgic/vgic.h | 9 ++++++++-
> 4 files changed, 51 insertions(+), 9 deletions(-)
>
> diff --git a/include/kvm/arm_vgic.h b/include/kvm/arm_vgic.h
> index ef71858..695ebc7 100644
> --- a/include/kvm/arm_vgic.h
> +++ b/include/kvm/arm_vgic.h
> @@ -112,6 +112,7 @@ struct vgic_irq {
> bool hw; /* Tied to HW IRQ */
> struct kref refcount; /* Used for LPIs */
> u32 hwintid; /* HW INTID number */
> + unsigned int host_irq; /* linux irq corresponding to hwintid */
> union {
> u8 targets; /* GICv2 target VCPUs mask */
> u32 mpidr; /* GICv3 target VCPU */
> @@ -301,7 +302,8 @@ int kvm_vgic_inject_irq(struct kvm *kvm, int cpuid, unsigned int intid,
> bool level);
> int kvm_vgic_inject_mapped_irq(struct kvm *kvm, int cpuid, unsigned int intid,
> bool level);
> -int kvm_vgic_map_phys_irq(struct kvm_vcpu *vcpu, u32 virt_irq, u32 phys_irq);
> +int kvm_vgic_map_phys_irq(struct kvm_vcpu *vcpu, unsigned int host_irq,
> + u32 virt_irq, u32 phys_irq);
> int kvm_vgic_unmap_phys_irq(struct kvm_vcpu *vcpu, unsigned int virt_irq);
> bool kvm_vgic_map_is_active(struct kvm_vcpu *vcpu, unsigned int virt_irq);
>
> diff --git a/virt/kvm/arm/arch_timer.c b/virt/kvm/arm/arch_timer.c
> index 5976609..45f4779 100644
> --- a/virt/kvm/arm/arch_timer.c
> +++ b/virt/kvm/arm/arch_timer.c
> @@ -651,7 +651,8 @@ int kvm_timer_enable(struct kvm_vcpu *vcpu)
> * Tell the VGIC that the virtual interrupt is tied to a
> * physical interrupt. We do that once per VCPU.
> */
> - ret = kvm_vgic_map_phys_irq(vcpu, vtimer->irq.irq, phys_irq);
> + ret = kvm_vgic_map_phys_irq(vcpu, host_vtimer_irq,
> + vtimer->irq.irq, phys_irq);
> if (ret)
> return ret;
>
> diff --git a/virt/kvm/arm/vgic/vgic.c b/virt/kvm/arm/vgic/vgic.c
> index 83b24d2..aa0618c 100644
> --- a/virt/kvm/arm/vgic/vgic.c
> +++ b/virt/kvm/arm/vgic/vgic.c
> @@ -137,6 +137,28 @@ void vgic_put_irq(struct kvm *kvm, struct vgic_irq *irq)
> kfree(irq);
> }
>
> +bool irq_line_level(struct vgic_irq *irq)
> +{
> + bool line_level = irq->line_level;
> +
> + if (unlikely(is_unshared_mapped(irq)))

The "unshared" bit doesn't mean much to me. Do you want to say "an
interrupt that belongs to a device only accessed by a single VM"?

Given that this can only be an SPI, can we use something like
"is_mapped_spi()" instead? I find it a lot more readable, but I'm open
to alternative suggestions.

> + WARN_ON(irq_get_irqchip_state(irq->host_irq,
> + IRQCHIP_STATE_PENDING,
> + &line_level));
> + return line_level;
> +}
> +
> +bool irq_is_active(struct vgic_irq *irq)
> +{
> + bool is_active = irq->active;
> +
> + if (unlikely(is_unshared_mapped(irq)))
> + WARN_ON(irq_get_irqchip_state(irq->host_irq,
> + IRQCHIP_STATE_ACTIVE,
> + &is_active));
> + return is_active;
> +}
> +
> /**
> * kvm_vgic_target_oracle - compute the target vcpu for an irq
> *
> @@ -153,7 +175,7 @@ static struct kvm_vcpu *vgic_target_oracle(struct vgic_irq *irq)
> DEBUG_SPINLOCK_BUG_ON(!spin_is_locked(&irq->irq_lock));
>
> /* If the interrupt is active, it must stay on the current vcpu */
> - if (irq->active)
> + if (irq_is_active(irq))
> return irq->vcpu ? : irq->target_vcpu;
>
> /*
> @@ -195,14 +217,18 @@ static int vgic_irq_cmp(void *priv, struct list_head *a, struct list_head *b)
> {
> struct vgic_irq *irqa = container_of(a, struct vgic_irq, ap_list);
> struct vgic_irq *irqb = container_of(b, struct vgic_irq, ap_list);
> + bool activea, activeb;
> bool penda, pendb;
> int ret;
>
> spin_lock(&irqa->irq_lock);
> spin_lock_nested(&irqb->irq_lock, SINGLE_DEPTH_NESTING);
>
> - if (irqa->active || irqb->active) {
> - ret = (int)irqb->active - (int)irqa->active;
> + activea = irq_is_active(irqa);
> + activeb = irq_is_active(irqb);
> +
> + if (activea || activeb) {
> + ret = (int)activeb - (int)activea;
> goto out;
> }
>
> @@ -234,13 +260,17 @@ static void vgic_sort_ap_list(struct kvm_vcpu *vcpu)
>
> /*
> * Only valid injection if changing level for level-triggered IRQs or for a
> - * rising edge.
> + * rising edge. Injection of virtual interrupts associated to physical
> + * interrupts always is valid.
> */
> static bool vgic_validate_injection(struct vgic_irq *irq, bool level)
> {
> switch (irq->config) {
> case VGIC_CONFIG_LEVEL:
> - return irq->line_level != level;
> + if (unlikely(is_unshared_mapped(irq)))
> + return true;
> + else
> + return irq->line_level != level;

This would be more readable as:

return (irq->line_level != level ||
unlikely(is_unshared_mapped(irq)));

> case VGIC_CONFIG_EDGE:
> return level;
> }
> @@ -392,7 +422,8 @@ int kvm_vgic_inject_irq(struct kvm *kvm, int cpuid, unsigned int intid,
> return 0;
> }
>
> -int kvm_vgic_map_phys_irq(struct kvm_vcpu *vcpu, u32 virt_irq, u32 phys_irq)
> +int kvm_vgic_map_phys_irq(struct kvm_vcpu *vcpu, unsigned int host_irq,
> + u32 virt_irq, u32 phys_irq)
> {
> struct vgic_irq *irq = vgic_get_irq(vcpu->kvm, vcpu, virt_irq);
>
> @@ -402,6 +433,7 @@ int kvm_vgic_map_phys_irq(struct kvm_vcpu *vcpu, u32 virt_irq, u32 phys_irq)
>
> irq->hw = true;
> irq->hwintid = phys_irq;
> + irq->host_irq = host_irq;

If you're now passing the Linux IRQ to the mapping function, you might
as well move the code that extracts the host hwirq here as well.

>
> spin_unlock(&irq->irq_lock);
> vgic_put_irq(vcpu->kvm, irq);
> diff --git a/virt/kvm/arm/vgic/vgic.h b/virt/kvm/arm/vgic/vgic.h
> index da83e4c..dc4972b 100644
> --- a/virt/kvm/arm/vgic/vgic.h
> +++ b/virt/kvm/arm/vgic/vgic.h
> @@ -17,6 +17,7 @@
> #define __KVM_ARM_VGIC_NEW_H__
>
> #include <linux/irqchip/arm-gic-common.h>
> +#include <linux/interrupt.h>
>
> #define PRODUCT_ID_KVM 0x4b /* ASCII code K */
> #define IMPLEMENTER_ARM 0x43b
> @@ -96,14 +97,20 @@
> /* we only support 64 kB translation table page size */
> #define KVM_ITS_L1E_ADDR_MASK GENMASK_ULL(51, 16)
>
> +bool irq_line_level(struct vgic_irq *irq);
> +bool irq_is_active(struct vgic_irq *irq);
> +
> static inline bool irq_is_pending(struct vgic_irq *irq)
> {
> if (irq->config == VGIC_CONFIG_EDGE)
> return irq->pending_latch;
> else
> - return irq->pending_latch || irq->line_level;
> + return irq->pending_latch || irq_line_level(irq);
> }
>
> +#define is_unshared_mapped(i) \
> +((i)->hw && (i)->intid >= VGIC_NR_PRIVATE_IRQS && (i)->intid < 1020)
> +
> /*
> * This struct provides an intermediate representation of the fields contained
> * in the GICH_VMCR and ICH_VMCR registers, such that code exporting the GIC

Thanks,

M.
--
Jazz is not dead, it just smell funny.