[PATCHv7 20/26] vfio/platform: trigger an interrupt via eventfd

[Antonios Motakis <a.motakis@virtualopensystems.com>]

This patch allows to set an eventfd for a patform device's interrupt,
and also to trigger the interrupt eventfd from userspace for testing.

Signed-off-by: Antonios Motakis <a.motakis@virtualopensystems.com>
---
 drivers/vfio/platform/vfio_platform_irq.c     | 89 ++++++++++++++++++++++++++-
 drivers/vfio/platform/vfio_platform_private.h |  2 +
 2 files changed, 89 insertions(+), 2 deletions(-)

diff --git a/drivers/vfio/platform/vfio_platform_irq.c b/drivers/vfio/platform/vfio_platform_irq.c
index 007b386..25a7825 100644
--- a/drivers/vfio/platform/vfio_platform_irq.c
+++ b/drivers/vfio/platform/vfio_platform_irq.c
@@ -45,11 +45,91 @@ static int vfio_platform_set_irq_unmask(struct vfio_platform_device *vdev,
 	return -EINVAL;
 }
 
+static irqreturn_t vfio_irq_handler(int irq, void *dev_id)
+{
+	struct vfio_platform_irq *irq_ctx = dev_id;
+
+	eventfd_signal(irq_ctx->trigger, 1);
+
+	return IRQ_HANDLED;
+}
+
+static int vfio_set_trigger(struct vfio_platform_device *vdev,
+			    int index, int fd)
+{
+	struct vfio_platform_irq *irq = &vdev->irqs[index];
+	struct eventfd_ctx *trigger;
+	int ret;
+
+	if (irq->trigger) {
+		free_irq(irq->hwirq, irq);
+		kfree(irq->name);
+		eventfd_ctx_put(irq->trigger);
+		irq->trigger = NULL;
+	}
+
+	if (fd < 0) /* Disable only */
+		return 0;
+
+	irq->name = kasprintf(GFP_KERNEL, "vfio-irq[%d](%s)",
+						irq->hwirq, vdev->name);
+	if (!irq->name)
+		return -ENOMEM;
+
+	trigger = eventfd_ctx_fdget(fd);
+	if (IS_ERR(trigger)) {
+		kfree(irq->name);
+		return PTR_ERR(trigger);
+	}
+
+	irq->trigger = trigger;
+
+	ret = request_irq(irq->hwirq, vfio_irq_handler, 0, irq->name, irq);
+	if (ret) {
+		kfree(irq->name);
+		eventfd_ctx_put(trigger);
+		irq->trigger = NULL;
+		return ret;
+	}
+
+	return 0;
+}
+
 static int vfio_platform_set_irq_trigger(struct vfio_platform_device *vdev,
 				     unsigned index, unsigned start,
 				     unsigned count, uint32_t flags, void *data)
 {
-	return -EINVAL;
+	struct vfio_platform_irq *irq = &vdev->irqs[index];
+	uint8_t irq_bitmap;
+	int32_t fd;
+
+	switch (flags & VFIO_IRQ_SET_DATA_TYPE_MASK) {
+	case VFIO_IRQ_SET_DATA_NONE:
+		if (count == 0)
+			return vfio_set_trigger(vdev, index, -1);
+
+		vfio_irq_handler(irq->hwirq, irq);
+		return 0;
+
+	case VFIO_IRQ_SET_DATA_BOOL:
+		if (copy_from_user(&irq_bitmap, data, sizeof(uint8_t)))
+			return -EFAULT;
+
+		if (irq_bitmap == 0x1) {
+			vfio_irq_handler(irq->hwirq, irq);
+			return 0;
+		}
+
+		return -EINVAL;
+
+	case VFIO_IRQ_SET_DATA_EVENTFD:
+		if (copy_from_user(&fd, data, sizeof(int32_t)))
+			return -EFAULT;
+
+		return vfio_set_trigger(vdev, index, fd);
+	}
+
+	return -EFAULT;
 }
 
 int vfio_platform_set_irqs_ioctl(struct vfio_platform_device *vdev,
@@ -95,7 +175,7 @@ int vfio_platform_irq_init(struct vfio_platform_device *vdev)
 		if (hwirq < 0)
 			goto err;
 
-		vdev->irqs[i].flags = 0;
+		vdev->irqs[i].flags = VFIO_IRQ_INFO_EVENTFD;
 		vdev->irqs[i].count = 1;
 		vdev->irqs[i].hwirq = hwirq;
 	}
@@ -110,6 +190,11 @@ err:
 
 void vfio_platform_irq_cleanup(struct vfio_platform_device *vdev)
 {
+	int i;
+
+	for (i = 0; i < vdev->num_irqs; i++)
+		vfio_set_trigger(vdev, i, -1);
+
 	vdev->num_irqs = 0;
 	kfree(vdev->irqs);
 }
diff --git a/drivers/vfio/platform/vfio_platform_private.h b/drivers/vfio/platform/vfio_platform_private.h
index 4201b94..765b371 100644
--- a/drivers/vfio/platform/vfio_platform_private.h
+++ b/drivers/vfio/platform/vfio_platform_private.h
@@ -28,6 +28,8 @@ struct vfio_platform_irq {
 	u32			flags;
 	u32			count;
 	int			hwirq;
+	char			*name;
+	struct eventfd_ctx	*trigger;
 };
 
 struct vfio_platform_region {
-- 
1.8.3.2