2 files changed, 123 insertions, 12 deletions

diff --git a/include/kvm/arm_vgic.h b/include/kvm/arm_vgic.h
index 7d8e61fa9928..f074539c6ac5 100644
--- a/include/kvm/arm_vgic.h
+++ b/include/kvm/arm_vgic.h
@@ -140,9 +140,23 @@ struct vgic_dist {
 	/* Interrupt enabled (one bit per IRQ) */
 	struct vgic_bitmap	irq_enabled;
 
-	/* Interrupt state is pending on the distributor */
+	/* Level-triggered interrupt external input is asserted */
+	struct vgic_bitmap	irq_level;
+
+	/*
+	 * Interrupt state is pending on the distributor
+	 */
 	struct vgic_bitmap	irq_pending;
 
+	/*
+	 * Tracks writes to GICD_ISPENDRn and GICD_ICPENDRn for level-triggered
+	 * interrupts.  Essentially holds the state of the flip-flop in
+	 * Figure 4-10 on page 4-101 in ARM IHI 0048B.b.
+	 * Once set, it is only cleared for level-triggered interrupts on
+	 * guest ACKs (when we queue it) or writes to GICD_ICPENDRn.
+	 */
+	struct vgic_bitmap	irq_soft_pend;
+
 	/* Level-triggered interrupt queued on VCPU interface */
 	struct vgic_bitmap	irq_queued;
 
diff --git a/virt/kvm/arm/vgic.c b/virt/kvm/arm/vgic.c
index 2026b6147805..435d8e7ad137 100644
--- a/virt/kvm/arm/vgic.c
+++ b/virt/kvm/arm/vgic.c
@@ -67,6 +67,11 @@
  * - When the interrupt is EOIed, the maintenance interrupt fires,
  *   and clears the corresponding bit in irq_queued. This allows the
  *   interrupt line to be sampled again.
+ * - Note that level-triggered interrupts can also be set to pending from
+ *   writes to GICD_ISPENDRn and lowering the external input line does not
+ *   cause the interrupt to become inactive in such a situation.
+ *   Conversely, writes to GICD_ICPENDRn do not cause the interrupt to become
+ *   inactive as long as the external input line is held high.
  */
 
 #define VGIC_ADDR_UNDEF		(-1)
@@ -217,6 +222,41 @@ static void vgic_irq_clear_queued(struct kvm_vcpu *vcpu, int irq)
 	vgic_bitmap_set_irq_val(&dist->irq_queued, vcpu->vcpu_id, irq, 0);
 }
 
+static int vgic_dist_irq_get_level(struct kvm_vcpu *vcpu, int irq)
+{
+	struct vgic_dist *dist = &vcpu->kvm->arch.vgic;
+
+	return vgic_bitmap_get_irq_val(&dist->irq_level, vcpu->vcpu_id, irq);
+}
+
+static void vgic_dist_irq_set_level(struct kvm_vcpu *vcpu, int irq)
+{
+	struct vgic_dist *dist = &vcpu->kvm->arch.vgic;
+
+	vgic_bitmap_set_irq_val(&dist->irq_level, vcpu->vcpu_id, irq, 1);
+}
+
+static void vgic_dist_irq_clear_level(struct kvm_vcpu *vcpu, int irq)
+{
+	struct vgic_dist *dist = &vcpu->kvm->arch.vgic;
+
+	vgic_bitmap_set_irq_val(&dist->irq_level, vcpu->vcpu_id, irq, 0);
+}
+
+static int vgic_dist_irq_soft_pend(struct kvm_vcpu *vcpu, int irq)
+{
+	struct vgic_dist *dist = &vcpu->kvm->arch.vgic;
+
+	return vgic_bitmap_get_irq_val(&dist->irq_soft_pend, vcpu->vcpu_id, irq);
+}
+
+static void vgic_dist_irq_clear_soft_pend(struct kvm_vcpu *vcpu, int irq)
+{
+	struct vgic_dist *dist = &vcpu->kvm->arch.vgic;
+
+	vgic_bitmap_set_irq_val(&dist->irq_soft_pend, vcpu->vcpu_id, irq, 0);
+}
+
 static int vgic_dist_irq_is_pending(struct kvm_vcpu *vcpu, int irq)
 {
 	struct vgic_dist *dist = &vcpu->kvm->arch.vgic;
@@ -414,11 +454,26 @@ static bool handle_mmio_set_pending_reg(struct kvm_vcpu *vcpu,
 					struct kvm_exit_mmio *mmio,
 					phys_addr_t offset)
 {
-	u32 *reg = vgic_bitmap_get_reg(&vcpu->kvm->arch.vgic.irq_pending,
-				       vcpu->vcpu_id, offset);
+	u32 *reg;
+	u32 level_mask;
+	struct vgic_dist *dist = &vcpu->kvm->arch.vgic;
+
+	reg = vgic_bitmap_get_reg(&dist->irq_cfg, vcpu->vcpu_id, offset);
+	level_mask = (~(*reg));
+
+	/* Mark both level and edge triggered irqs as pending */
+	reg = vgic_bitmap_get_reg(&dist->irq_pending, vcpu->vcpu_id, offset);
 	vgic_reg_access(mmio, reg, offset,
 			ACCESS_READ_VALUE | ACCESS_WRITE_SETBIT);
+
 	if (mmio->is_write) {
+		/* Set the soft-pending flag only for level-triggered irqs */
+		reg = vgic_bitmap_get_reg(&dist->irq_soft_pend,
+					  vcpu->vcpu_id, offset);
+		vgic_reg_access(mmio, reg, offset,
+				ACCESS_READ_VALUE | ACCESS_WRITE_SETBIT);
+		*reg &= level_mask;
+
 		vgic_update_state(vcpu->kvm);
 		return true;
 	}
@@ -430,11 +485,27 @@ static bool handle_mmio_clear_pending_reg(struct kvm_vcpu *vcpu,
 					  struct kvm_exit_mmio *mmio,
 					  phys_addr_t offset)
 {
-	u32 *reg = vgic_bitmap_get_reg(&vcpu->kvm->arch.vgic.irq_pending,
-				       vcpu->vcpu_id, offset);
+	u32 *level_active;
+	u32 *reg;
+	struct vgic_dist *dist = &vcpu->kvm->arch.vgic;
+
+	reg = vgic_bitmap_get_reg(&dist->irq_pending, vcpu->vcpu_id, offset);
 	vgic_reg_access(mmio, reg, offset,
 			ACCESS_READ_VALUE | ACCESS_WRITE_CLEARBIT);
 	if (mmio->is_write) {
+		/* Re-set level triggered level-active interrupts */
+		level_active = vgic_bitmap_get_reg(&dist->irq_level,
+					  vcpu->vcpu_id, offset);
+		reg = vgic_bitmap_get_reg(&dist->irq_pending,
+					  vcpu->vcpu_id, offset);
+		*reg |= *level_active;
+
+		/* Clear soft-pending flags */
+		reg = vgic_bitmap_get_reg(&dist->irq_soft_pend,
+					  vcpu->vcpu_id, offset);
+		vgic_reg_access(mmio, reg, offset,
+				ACCESS_READ_VALUE | ACCESS_WRITE_CLEARBIT);
+
 		vgic_update_state(vcpu->kvm);
 		return true;
 	}
@@ -1268,17 +1339,32 @@ static bool vgic_process_maintenance(struct kvm_vcpu *vcpu)
 
 		for_each_set_bit(lr, eisr_ptr, vgic->nr_lr) {
 			struct vgic_lr vlr = vgic_get_lr(vcpu, lr);
+			WARN_ON(vgic_irq_is_edge(vcpu, vlr.irq));
 
 			vgic_irq_clear_queued(vcpu, vlr.irq);
 			WARN_ON(vlr.state & LR_STATE_MASK);
 			vlr.state = 0;
 			vgic_set_lr(vcpu, lr, vlr);
 
+			/*
+			 * If the IRQ was EOIed it was also ACKed and we we
+			 * therefore assume we can clear the soft pending
+			 * state (should it had been set) for this interrupt.
+			 *
+			 * Note: if the IRQ soft pending state was set after
+			 * the IRQ was acked, it actually shouldn't be
+			 * cleared, but we have no way of knowing that unless
+			 * we start trapping ACKs when the soft-pending state
+			 * is set.
+			 */
+			vgic_dist_irq_clear_soft_pend(vcpu, vlr.irq);
+
 			/* Any additional pending interrupt? */
-			if (vgic_dist_irq_is_pending(vcpu, vlr.irq)) {
+			if (vgic_dist_irq_get_level(vcpu, vlr.irq)) {
 				vgic_cpu_irq_set(vcpu, vlr.irq);
 				level_pending = true;
 			} else {
+				vgic_dist_irq_clear_pending(vcpu, vlr.irq);
 				vgic_cpu_irq_clear(vcpu, vlr.irq);
 			}
 
@@ -1384,17 +1470,19 @@ static void vgic_kick_vcpus(struct kvm *kvm)
 static int vgic_validate_injection(struct kvm_vcpu *vcpu, int irq, int level)
 {
 	int edge_triggered = 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 (edge_triggered)
+	if (edge_triggered) {
+		int state = vgic_dist_irq_is_pending(vcpu, irq);
 		return level > state;
-	else
+	} else {
+		int state = vgic_dist_irq_get_level(vcpu, irq);
 		return level != state;
+	}
 }
 
 static bool vgic_update_irq_pending(struct kvm *kvm, int cpuid,
@@ -1424,10 +1512,19 @@ static bool vgic_update_irq_pending(struct kvm *kvm, int cpuid,
 
 	kvm_debug("Inject IRQ%d level %d CPU%d\n", irq_num, level, cpuid);
 
-	if (level)
+	if (level) {
+		if (level_triggered)
+			vgic_dist_irq_set_level(vcpu, irq_num);
 		vgic_dist_irq_set_pending(vcpu, irq_num);
-	else
-		vgic_dist_irq_clear_pending(vcpu, irq_num);
+	} else {
+		if (level_triggered) {
+			vgic_dist_irq_clear_level(vcpu, irq_num);
+			if (!vgic_dist_irq_soft_pend(vcpu, irq_num))
+				vgic_dist_irq_clear_pending(vcpu, irq_num);
+		} else {
+			vgic_dist_irq_clear_pending(vcpu, irq_num);
+		}
+	}
 
 	enabled = vgic_irq_is_enabled(vcpu, irq_num);