KVM: arm/arm64: Support a vgic interrupt line level sample function

The GIC sometimes need to sample the physical line of a mapped
interrupt.  As we know this to be notoriously slow, provide a callback
function for devices (such as the timer) which can do this much faster
than talking to the distributor, for example by comparing a few
in-memory values.  Fall back to the good old method of poking the
physical GIC if no callback is provided.

Reviewed-by: Marc Zyngier <marc.zyngier@arm.com>
Reviewed-by: Eric Auger <eric.auger@redhat.com>
Signed-off-by: Christoffer Dall <christoffer.dall@linaro.org>

diff --git a/include/kvm/arm_vgic.h b/include/kvm/arm_vgic.h
index 8c89654..cdbd142 100644 (file)
--- a/include/kvm/arm_vgic.h
+++ b/include/kvm/arm_vgic.h
@@ -130,6 +130,17 @@ struct vgic_irq {
        u8 priority;
        enum vgic_irq_config config;    /* Level or edge */
 
+       /*
+        * Callback function pointer to in-kernel devices that can tell us the
+        * state of the input level of mapped level-triggered IRQ faster than
+        * peaking into the physical GIC.
+        *
+        * Always called in non-preemptible section and the functions can use
+        * kvm_arm_get_running_vcpu() to get the vcpu pointer for private
+        * IRQs.
+        */
+       bool (*get_input_level)(int vintid);
+
        void *owner;                    /* Opaque pointer to reserve an interrupt
                                           for in-kernel devices. */
 };
@@ -331,7 +342,7 @@ void kvm_vgic_init_cpu_hardware(void);
 int kvm_vgic_inject_irq(struct kvm *kvm, int cpuid, unsigned int intid,
                        bool level, void *owner);
 int kvm_vgic_map_phys_irq(struct kvm_vcpu *vcpu, unsigned int host_irq,
-                         u32 vintid);
+                         u32 vintid, bool (*get_input_level)(int vindid));
 int kvm_vgic_unmap_phys_irq(struct kvm_vcpu *vcpu, unsigned int vintid);
 bool kvm_vgic_map_is_active(struct kvm_vcpu *vcpu, unsigned int vintid);
 

diff --git a/virt/kvm/arm/arch_timer.c b/virt/kvm/arm/arch_timer.c
index 9376fe0..fb0533e 100644 (file)
--- a/virt/kvm/arm/arch_timer.c
+++ b/virt/kvm/arm/arch_timer.c
@@ -834,7 +834,8 @@ int kvm_timer_enable(struct kvm_vcpu *vcpu)
                return -EINVAL;
        }
 
-       ret = kvm_vgic_map_phys_irq(vcpu, host_vtimer_irq, vtimer->irq.irq);
+       ret = kvm_vgic_map_phys_irq(vcpu, host_vtimer_irq, vtimer->irq.irq,
+                                   NULL);
        if (ret)
                return ret;
 

diff --git a/virt/kvm/arm/vgic/vgic.c b/virt/kvm/arm/vgic/vgic.c
index 4318e9e..d57b3bf 100644 (file)
--- a/virt/kvm/arm/vgic/vgic.c
+++ b/virt/kvm/arm/vgic/vgic.c
@@ -144,13 +144,15 @@ void vgic_put_irq(struct kvm *kvm, struct vgic_irq *irq)
        kfree(irq);
 }
 
-/* Get the input level of a mapped IRQ directly from the physical GIC */
 bool vgic_get_phys_line_level(struct vgic_irq *irq)
 {
        bool line_level;
 
        BUG_ON(!irq->hw);
 
+       if (irq->get_input_level)
+               return irq->get_input_level(irq->intid);
+
        WARN_ON(irq_get_irqchip_state(irq->host_irq,
                                      IRQCHIP_STATE_PENDING,
                                      &line_level));
@@ -436,7 +438,8 @@ int kvm_vgic_inject_irq(struct kvm *kvm, int cpuid, unsigned int intid,
 
 /* @irq->irq_lock must be held */
 static int kvm_vgic_map_irq(struct kvm_vcpu *vcpu, struct vgic_irq *irq,
-                           unsigned int host_irq)
+                           unsigned int host_irq,
+                           bool (*get_input_level)(int vindid))
 {
        struct irq_desc *desc;
        struct irq_data *data;
@@ -456,6 +459,7 @@ static int kvm_vgic_map_irq(struct kvm_vcpu *vcpu, struct vgic_irq *irq,
        irq->hw = true;
        irq->host_irq = host_irq;
        irq->hwintid = data->hwirq;
+       irq->get_input_level = get_input_level;
        return 0;
 }
 
@@ -464,10 +468,11 @@ static inline void kvm_vgic_unmap_irq(struct vgic_irq *irq)
 {
        irq->hw = false;
        irq->hwintid = 0;
+       irq->get_input_level = NULL;
 }
 
 int kvm_vgic_map_phys_irq(struct kvm_vcpu *vcpu, unsigned int host_irq,
-                         u32 vintid)
+                         u32 vintid, bool (*get_input_level)(int vindid))
 {
        struct vgic_irq *irq = vgic_get_irq(vcpu->kvm, vcpu, vintid);
        unsigned long flags;
@@ -476,7 +481,7 @@ int kvm_vgic_map_phys_irq(struct kvm_vcpu *vcpu, unsigned int host_irq,
        BUG_ON(!irq);
 
        spin_lock_irqsave(&irq->irq_lock, flags);
-       ret = kvm_vgic_map_irq(vcpu, irq, host_irq);
+       ret = kvm_vgic_map_irq(vcpu, irq, host_irq, get_input_level);
        spin_unlock_irqrestore(&irq->irq_lock, flags);
        vgic_put_irq(vcpu->kvm, irq);