ARM: KVM: VGIC interrupt injection

Plug the interrupt injection code. Interrupts can now be generated
from user space.

Reviewed-by: Will Deacon <will.deacon@arm.com>
Signed-off-by: Christoffer Dall <c.dall@virtualopensystems.com>
Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>

1 files changed, 117 insertions, 0 deletions

diff --git a/arch/arm/kvm/vgic.c b/arch/arm/kvm/vgic.c
index 2d5e29f1c28f..2e6a585c23e5 100644
--- a/arch/arm/kvm/vgic.c
+++ b/arch/arm/kvm/vgic.c
@@ -73,6 +73,7 @@
 
 static void vgic_retire_disabled_irqs(struct kvm_vcpu *vcpu);
 static void vgic_update_state(struct kvm *kvm);
+static void vgic_kick_vcpus(struct kvm *kvm);
 static void vgic_dispatch_sgi(struct kvm_vcpu *vcpu, u32 reg);
 
 static u32 *vgic_bitmap_get_reg(struct vgic_bitmap *x,
@@ -708,6 +709,9 @@ bool vgic_handle_mmio(struct kvm_vcpu *vcpu, struct kvm_run *run,
         kvm_prepare_mmio(run, mmio);
         kvm_handle_mmio_return(vcpu, run);
 
+        if (updated_state)
+                vgic_kick_vcpus(vcpu->kvm);
+
         return true;
 }
 
@@ -1104,6 +1108,119 @@ int kvm_vgic_vcpu_pending_irq(struct kvm_vcpu *vcpu)
         return test_bit(vcpu->vcpu_id, &dist->irq_pending_on_cpu);
 }
 
+static void vgic_kick_vcpus(struct kvm *kvm)
+{
+        struct kvm_vcpu *vcpu;
+        int c;
+
+        /*
+         * We've injected an interrupt, time to find out who deserves
+         * a good kick...
+         */
+        kvm_for_each_vcpu(c, vcpu, kvm) {
+                if (kvm_vgic_vcpu_pending_irq(vcpu))
+                        kvm_vcpu_kick(vcpu);
+        }
+}
+
+static int vgic_validate_injection(struct kvm_vcpu *vcpu, int irq, int level)
+{
+        int is_edge = vgic_irq_is_edge(vcpu, irq);
+        int state = vgic_dist_irq_is_pending(vcpu, irq);
+
+        /*
+         * Only inject an interrupt if:
+         * - edge triggered and we have a rising edge
+         * - level triggered and we change level
+         */
+        if (is_edge)
+                return level > state;
+        else
+                return level != state;
+}
+
+static bool vgic_update_irq_state(struct kvm *kvm, int cpuid,
+                                  unsigned int irq_num, bool level)
+{
+        struct vgic_dist *dist = &kvm->arch.vgic;
+        struct kvm_vcpu *vcpu;
+        int is_edge, is_level;
+        int enabled;
+        bool ret = true;
+
+        spin_lock(&dist->lock);
+
+        vcpu = kvm_get_vcpu(kvm, cpuid);
+        is_edge = vgic_irq_is_edge(vcpu, irq_num);
+        is_level = !is_edge;
+
+        if (!vgic_validate_injection(vcpu, irq_num, level)) {
+                ret = false;
+                goto out;
+        }
+
+        if (irq_num >= VGIC_NR_PRIVATE_IRQS) {
+                cpuid = dist->irq_spi_cpu[irq_num - VGIC_NR_PRIVATE_IRQS];
+                vcpu = kvm_get_vcpu(kvm, cpuid);
+        }
+
+        kvm_debug("Inject IRQ%d level %d CPU%d\n", irq_num, level, cpuid);
+
+        if (level)
+                vgic_dist_irq_set(vcpu, irq_num);
+        else
+                vgic_dist_irq_clear(vcpu, irq_num);
+
+        enabled = vgic_irq_is_enabled(vcpu, irq_num);
+
+        if (!enabled) {
+                ret = false;
+                goto out;
+        }
+
+        if (is_level && vgic_irq_is_active(vcpu, irq_num)) {
+                /*
+                 * Level interrupt in progress, will be picked up
+                 * when EOId.
+                 */
+                ret = false;
+                goto out;
+        }
+
+        if (level) {
+                vgic_cpu_irq_set(vcpu, irq_num);
+                set_bit(cpuid, &dist->irq_pending_on_cpu);
+        }
+
+out:
+        spin_unlock(&dist->lock);
+
+        return ret;
+}
+
+/**
+ * kvm_vgic_inject_irq - Inject an IRQ from a device to the vgic
+ * @kvm:     The VM structure pointer
+ * @cpuid:   The CPU for PPIs
+ * @irq_num: The IRQ number that is assigned to the device
+ * @level:   Edge-triggered:  true:  to trigger the interrupt
+ *                            false: to ignore the call
+ *           Level-sensitive  true:  activates an interrupt
+ *                            false: deactivates an interrupt
+ *
+ * The GIC is not concerned with devices being active-LOW or active-HIGH for
+ * level-sensitive interrupts.  You can think of the level parameter as 1
+ * being HIGH and 0 being LOW and all devices being active-HIGH.
+ */
+int kvm_vgic_inject_irq(struct kvm *kvm, int cpuid, unsigned int irq_num,
+                        bool level)
+{
+        if (vgic_update_irq_state(kvm, cpuid, irq_num, level))
+                vgic_kick_vcpus(kvm);
+
+        return 0;
+}
+
 static bool vgic_ioaddr_overlap(struct kvm *kvm)
 {
         phys_addr_t dist = kvm->arch.vgic.vgic_dist_base;