vfio fsl-mc: trigger an interrupt via eventfd

This patch allows to set an eventfd for fsl-mc device interrupt
and also to trigger the interrupt eventfd from userspace for testing.

All fsl-mc device interrupts are MSI type. This does not yet handler
correctly DPRC container interrupt where re-scanning on container is
required.

Signed-off-by: Bharat Bhushan <Bharat.Bhushan@nxp.com>

2 files changed, 107 insertions, 19 deletions

diff --git a/drivers/vfio/fsl-mc/vfio_fsl_mc_intr.c b/drivers/vfio/fsl-mc/vfio_fsl_mc_intr.c
index b7baf10..eb244bb 100644
--- a/drivers/vfio/fsl-mc/vfio_fsl_mc_intr.c
+++ b/drivers/vfio/fsl-mc/vfio_fsl_mc_intr.c
@@ -12,9 +12,79 @@
 #include <linux/vfio.h>
 #include <linux/slab.h>
 #include <linux/types.h>
+#include <linux/eventfd.h>
+#include <linux/msi.h>
 
-#include "vfio_fsl_mc_private.h"
 #include "../../staging/fsl-mc/include/mc.h"
+#include "vfio_fsl_mc_private.h"
+
+static irqreturn_t vfio_fsl_mc_irq_handler(int irq_num, void *arg)
+{
+	struct vfio_fsl_mc_irq *mc_irq = (struct vfio_fsl_mc_irq *)arg;
+
+	eventfd_signal(mc_irq->trigger, 1);
+	return IRQ_HANDLED;
+}
+
+static int vfio_fsl_mc_irq_mask(struct vfio_fsl_mc_device *vdev,
+				unsigned int index, unsigned int start,
+				unsigned int count, uint32_t flags,
+				void *data)
+{
+	return -EINVAL;
+}
+
+static int vfio_fsl_mc_irq_unmask(struct vfio_fsl_mc_device *vdev,
+				unsigned int index, unsigned int start,
+				unsigned int count, uint32_t flags,
+				void *data)
+{
+	return -EINVAL;
+}
+
+static int vfio_set_trigger(struct vfio_fsl_mc_device *vdev,
+			    int index, int fd)
+{
+	struct vfio_fsl_mc_irq *irq = &vdev->mc_irqs[index];
+	struct eventfd_ctx *trigger;
+	int hwirq;
+	int ret;
+
+	hwirq = vdev->mc_dev->irqs[index]->msi_desc->irq;
+	if (irq->trigger) {
+		free_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)",
+					hwirq, dev_name(&vdev->mc_dev->dev));
+	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(hwirq, vfio_fsl_mc_irq_handler, 0,
+			  irq->name, irq);
+	if (ret) {
+		kfree(irq->name);
+		eventfd_ctx_put(trigger);
+		irq->trigger = NULL;
+		return ret;
+	}
+
+	return 0;
+}
 
 int vfio_fsl_mc_irqs_init(struct vfio_fsl_mc_device *vdev)
 {
@@ -42,7 +112,7 @@ int vfio_fsl_mc_irqs_init(struct vfio_fsl_mc_device *vdev)
 
 	for (i = 0; i < irq_count; i++) {
 		mc_irq[i].count = 1;
-		mc_irq[i].flags = 0;
+		mc_irq[i].flags = VFIO_IRQ_INFO_EVENTFD;
 	}
 
 	vdev->mc_irqs = mc_irq;
@@ -54,37 +124,53 @@ int vfio_fsl_mc_irqs_init(struct vfio_fsl_mc_device *vdev)
 void vfio_fsl_mc_irqs_cleanup(struct vfio_fsl_mc_device *vdev)
 {
 	struct fsl_mc_device *mc_dev = vdev->mc_dev;
+	int irq_count = mc_dev->obj_desc.irq_count;
+	int i;
 
 	/* Device does not support any interrupt */
 	if (mc_dev->obj_desc.irq_count == 0)
 		return;
 
+	for (i = 0; i < irq_count; i++)
+		vfio_set_trigger(vdev, i, -1);
+
 	fsl_mc_free_irqs(mc_dev);
 	kfree(vdev->mc_irqs);
 }
 
-static int vfio_fsl_mc_irq_mask(struct vfio_fsl_mc_device *vdev,
-				unsigned int index, unsigned int start,
-				unsigned int count, uint32_t flags,
-				void *data)
-{
-	return -EINVAL;
-}
-
-static int vfio_fsl_mc_irq_unmask(struct vfio_fsl_mc_device *vdev,
-				unsigned int index, unsigned int start,
-				unsigned int count, uint32_t flags,
-				void *data)
-{
-	return -EINVAL;
-}
-
 static int vfio_fsl_mc_set_irq_trigger(struct vfio_fsl_mc_device *vdev,
 				       unsigned int index, unsigned int start,
 				       unsigned int count, uint32_t flags,
 				       void *data)
 {
-	return -EINVAL;
+	struct vfio_fsl_mc_irq *irq = &vdev->mc_irqs[index];
+	int hwirq;
+
+	if (!count && (flags & VFIO_IRQ_SET_DATA_NONE))
+		return vfio_set_trigger(vdev, index, -1);
+
+	if (start != 0 || count != 1)
+		return -EINVAL;
+
+	if (flags & VFIO_IRQ_SET_DATA_EVENTFD) {
+		int32_t fd = *(int32_t *)data;
+
+		return vfio_set_trigger(vdev, index, fd);
+	}
+
+	hwirq = vdev->mc_dev->irqs[index]->msi_desc->irq;
+
+	if (flags & VFIO_IRQ_SET_DATA_NONE) {
+		vfio_fsl_mc_irq_handler(hwirq, irq);
+
+	} else if (flags & VFIO_IRQ_SET_DATA_BOOL) {
+		uint8_t trigger = *(uint8_t *)data;
+
+		if (trigger)
+			vfio_fsl_mc_irq_handler(hwirq, irq);
+	}
+
+	return 0;
 }
 
 int vfio_fsl_mc_set_irqs_ioctl(struct vfio_fsl_mc_device *vdev,
diff --git a/drivers/vfio/fsl-mc/vfio_fsl_mc_private.h b/drivers/vfio/fsl-mc/vfio_fsl_mc_private.h
index 3063fe9..46a0585 100644
--- a/drivers/vfio/fsl-mc/vfio_fsl_mc_private.h
+++ b/drivers/vfio/fsl-mc/vfio_fsl_mc_private.h
@@ -24,6 +24,8 @@
 struct vfio_fsl_mc_irq {
 	u32			flags;
 	u32			count;
+	struct eventfd_ctx	*trigger;
+	char			*name;
 };
 
 struct vfio_fsl_mc_region {