vfio/platform: support for level sensitive interrupts

Level sensitive interrupts are exposed as maskable and automasked
interrupts and are masked and disabled automatically when they fire.

Signed-off-by: Antonios Motakis <a.motakis@virtualopensystems.com>
[Baptiste Reynal: Move masked interrupt initialization from "vfio/platform:
trigger an interrupt via eventfd"]
Signed-off-by: Baptiste Reynal <b.reynal@virtualopensystems.com>
Reviewed-by: Eric Auger <eric.auger@linaro.org>
Tested-by: Eric Auger <eric.auger@linaro.org>
Signed-off-by: Alex Williamson <alex.williamson@redhat.com>

drivers/vfio/platform/vfio_platform_irq.c

@@ -23,12 +23,59 @@
 
 #include "vfio_platform_private.h"
 
+static void vfio_platform_mask(struct vfio_platform_irq *irq_ctx)
+{
+	unsigned long flags;
+
+	spin_lock_irqsave(&irq_ctx->lock, flags);
+
+	if (!irq_ctx->masked) {
+		disable_irq_nosync(irq_ctx->hwirq);
+		irq_ctx->masked = true;
+	}
+
+	spin_unlock_irqrestore(&irq_ctx->lock, flags);
+}
+
 static int vfio_platform_set_irq_mask(struct vfio_platform_device *vdev,
 				      unsigned index, unsigned start,
 				      unsigned count, uint32_t flags,
 				      void *data)
 {
-	return -EINVAL;
+	if (start != 0 || count != 1)
+		return -EINVAL;
+
+	if (!(vdev->irqs[index].flags & VFIO_IRQ_INFO_MASKABLE))
+		return -EINVAL;
+
+	if (flags & VFIO_IRQ_SET_DATA_EVENTFD)
+		return -EINVAL; /* not implemented yet */
+
+	if (flags & VFIO_IRQ_SET_DATA_NONE) {
+		vfio_platform_mask(&vdev->irqs[index]);
+
+	} else if (flags & VFIO_IRQ_SET_DATA_BOOL) {
+		uint8_t mask = *(uint8_t *)data;
+
+		if (mask)
+			vfio_platform_mask(&vdev->irqs[index]);
+	}
+
+	return 0;
+}
+
+static void vfio_platform_unmask(struct vfio_platform_irq *irq_ctx)
+{
+	unsigned long flags;
+
+	spin_lock_irqsave(&irq_ctx->lock, flags);
+
+	if (irq_ctx->masked) {
+		enable_irq(irq_ctx->hwirq);
+		irq_ctx->masked = false;
+	}
+
+	spin_unlock_irqrestore(&irq_ctx->lock, flags);
 }
 
 static int vfio_platform_set_irq_unmask(struct vfio_platform_device *vdev,
@@ -36,7 +83,50 @@ static int vfio_platform_set_irq_unmask(struct vfio_platform_device *vdev,
 					unsigned count, uint32_t flags,
 					void *data)
 {
-	return -EINVAL;
+	if (start != 0 || count != 1)
+		return -EINVAL;
+
+	if (!(vdev->irqs[index].flags & VFIO_IRQ_INFO_MASKABLE))
+		return -EINVAL;
+
+	if (flags & VFIO_IRQ_SET_DATA_EVENTFD)
+		return -EINVAL; /* not implemented yet */
+
+	if (flags & VFIO_IRQ_SET_DATA_NONE) {
+		vfio_platform_unmask(&vdev->irqs[index]);
+
+	} else if (flags & VFIO_IRQ_SET_DATA_BOOL) {
+		uint8_t unmask = *(uint8_t *)data;
+
+		if (unmask)
+			vfio_platform_unmask(&vdev->irqs[index]);
+	}
+
+	return 0;
+}
+
+static irqreturn_t vfio_automasked_irq_handler(int irq, void *dev_id)
+{
+	struct vfio_platform_irq *irq_ctx = dev_id;
+	unsigned long flags;
+	int ret = IRQ_NONE;
+
+	spin_lock_irqsave(&irq_ctx->lock, flags);
+
+	if (!irq_ctx->masked) {
+		ret = IRQ_HANDLED;
+
+		/* automask maskable interrupts */
+		disable_irq_nosync(irq_ctx->hwirq);
+		irq_ctx->masked = true;
+	}
+
+	spin_unlock_irqrestore(&irq_ctx->lock, flags);
+
+	if (ret == IRQ_HANDLED)
+		eventfd_signal(irq_ctx->trigger, 1);
+
+	return ret;
 }
 
 static irqreturn_t vfio_irq_handler(int irq, void *dev_id)
@@ -78,6 +168,7 @@ static int vfio_set_trigger(struct vfio_platform_device *vdev, int index,
 
 	irq->trigger = trigger;
 
+	irq_set_status_flags(irq->hwirq, IRQ_NOAUTOEN);
 	ret = request_irq(irq->hwirq, handler, 0, irq->name, irq);
 	if (ret) {
 		kfree(irq->name);
@@ -86,6 +177,9 @@ static int vfio_set_trigger(struct vfio_platform_device *vdev, int index,
 		return ret;
 	}
 
+	if (!irq->masked)
+		enable_irq(irq->hwirq);
+
 	return 0;
 }
 
@@ -98,7 +192,7 @@ static int vfio_platform_set_irq_trigger(struct vfio_platform_device *vdev,
 	irq_handler_t handler;
 
 	if (vdev->irqs[index].flags & VFIO_IRQ_INFO_AUTOMASKED)
-		return -EINVAL; /* not implemented */
+		handler = vfio_automasked_irq_handler;
 	else
 		handler = vfio_irq_handler;
 
@@ -170,6 +264,8 @@ int vfio_platform_irq_init(struct vfio_platform_device *vdev)
 		if (hwirq < 0)
 			goto err;
 
+		spin_lock_init(&vdev->irqs[i].lock);
+
 		vdev->irqs[i].flags = VFIO_IRQ_INFO_EVENTFD;
 
 		if (irq_get_trigger_type(hwirq) & IRQ_TYPE_LEVEL_MASK)
@@ -178,6 +274,7 @@ int vfio_platform_irq_init(struct vfio_platform_device *vdev)
 
 		vdev->irqs[i].count = 1;
 		vdev->irqs[i].hwirq = hwirq;
+		vdev->irqs[i].masked = false;
 	}
 
 	vdev->num_irqs = cnt;

drivers/vfio/platform/vfio_platform_private.h

@@ -33,6 +33,8 @@ struct vfio_platform_irq {
 	int			hwirq;
 	char			*name;
 	struct eventfd_ctx	*trigger;
+	bool			masked;
+	spinlock_t		lock;
 };
 
 struct vfio_platform_region {