vfio/fsl-mc: trigger an interrupt via eventfd

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

All fsl-mc device interrupts are MSIs. The MSIs are allocated from
the MSI domain only once per DPRC and used by all the DPAA2 objects.
The interrupts are managed by the DPRC in a pool of interrupts. Each
device requests interrupts from this pool. The pool is allocated
when the first virtual device is setting the interrupts.
The pool of interrupts is protected by a lock.

The DPRC has an interrupt of its own which indicates if the DPRC
contents have changed. However, currently, the contents of a DPRC
assigned to the guest cannot be changed at runtime, so this interrupt
is not configured.

Signed-off-by: Bharat Bhushan <Bharat.Bhushan@nxp.com>
Signed-off-by: Diana Craciun <diana.craciun@oss.nxp.com>
Reviewed-by: Eric Auger <eric.auger@redhat.com>
Signed-off-by: Alex Williamson <alex.williamson@redhat.com>

drivers/vfio/fsl-mc/vfio_fsl_mc.c

@@ -155,12 +155,34 @@ static int vfio_fsl_mc_open(void *device_data)
 static void vfio_fsl_mc_release(void *device_data)
 {
 	struct vfio_fsl_mc_device *vdev = device_data;
+	int ret;
 
 	mutex_lock(&vdev->reflck->lock);
 
-	if (!(--vdev->refcnt))
+	if (!(--vdev->refcnt)) {
+		struct fsl_mc_device *mc_dev = vdev->mc_dev;
+		struct device *cont_dev = fsl_mc_cont_dev(&mc_dev->dev);
+		struct fsl_mc_device *mc_cont = to_fsl_mc_device(cont_dev);
+
 		vfio_fsl_mc_regions_cleanup(vdev);
 
+		/* reset the device before cleaning up the interrupts */
+		ret = dprc_reset_container(mc_cont->mc_io, 0,
+		      mc_cont->mc_handle,
+			  mc_cont->obj_desc.id,
+			  DPRC_RESET_OPTION_NON_RECURSIVE);
+
+		if (ret) {
+			dev_warn(&mc_cont->dev, "VFIO_FLS_MC: reset device has failed (%d)\n",
+				 ret);
+			WARN_ON(1);
+		}
+
+		vfio_fsl_mc_irqs_cleanup(vdev);
+
+		fsl_mc_cleanup_irq_pool(mc_cont);
+	}
+
 	mutex_unlock(&vdev->reflck->lock);
 
 	module_put(THIS_MODULE);

drivers/vfio/fsl-mc/vfio_fsl_mc_intr.c

@@ -13,12 +13,150 @@
 #include "linux/fsl/mc.h"
 #include "vfio_fsl_mc_private.h"
 
+int vfio_fsl_mc_irqs_allocate(struct vfio_fsl_mc_device *vdev)
+{
+	struct fsl_mc_device *mc_dev = vdev->mc_dev;
+	struct vfio_fsl_mc_irq *mc_irq;
+	int irq_count;
+	int ret, i;
+
+	/* Device does not support any interrupt */
+	if (mc_dev->obj_desc.irq_count == 0)
+		return 0;
+
+	/* interrupts were already allocated for this device */
+	if (vdev->mc_irqs)
+		return 0;
+
+	irq_count = mc_dev->obj_desc.irq_count;
+
+	mc_irq = kcalloc(irq_count, sizeof(*mc_irq), GFP_KERNEL);
+	if (!mc_irq)
+		return -ENOMEM;
+
+	/* Allocate IRQs */
+	ret = fsl_mc_allocate_irqs(mc_dev);
+	if (ret) {
+		kfree(mc_irq);
+		return ret;
+	}
+
+	for (i = 0; i < irq_count; i++) {
+		mc_irq[i].count = 1;
+		mc_irq[i].flags = VFIO_IRQ_INFO_EVENTFD;
+	}
+
+	vdev->mc_irqs = mc_irq;
+
+	return 0;
+}
+
+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_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;
+}
+
 static int vfio_fsl_mc_set_irq_trigger(struct vfio_fsl_mc_device *vdev,
 				       unsigned int index, unsigned int start,
 				       unsigned int count, u32 flags,
 				       void *data)
 {
-	return -EINVAL;
+	struct fsl_mc_device *mc_dev = vdev->mc_dev;
+	int ret, hwirq;
+	struct vfio_fsl_mc_irq *irq;
+	struct device *cont_dev = fsl_mc_cont_dev(&mc_dev->dev);
+	struct fsl_mc_device *mc_cont = to_fsl_mc_device(cont_dev);
+
+	if (start != 0 || count != 1)
+		return -EINVAL;
+
+	mutex_lock(&vdev->reflck->lock);
+	ret = fsl_mc_populate_irq_pool(mc_cont,
+			FSL_MC_IRQ_POOL_MAX_TOTAL_IRQS);
+	if (ret)
+		goto unlock;
+
+	ret = vfio_fsl_mc_irqs_allocate(vdev);
+	if (ret)
+		goto unlock;
+	mutex_unlock(&vdev->reflck->lock);
+
+	if (!count && (flags & VFIO_IRQ_SET_DATA_NONE))
+		return vfio_set_trigger(vdev, index, -1);
+
+	if (flags & VFIO_IRQ_SET_DATA_EVENTFD) {
+		s32 fd = *(s32 *)data;
+
+		return vfio_set_trigger(vdev, index, fd);
+	}
+
+	hwirq = vdev->mc_dev->irqs[index]->msi_desc->irq;
+
+	irq = &vdev->mc_irqs[index];
+
+	if (flags & VFIO_IRQ_SET_DATA_NONE) {
+		vfio_fsl_mc_irq_handler(hwirq, irq);
+
+	} else if (flags & VFIO_IRQ_SET_DATA_BOOL) {
+		u8 trigger = *(u8 *)data;
+
+		if (trigger)
+			vfio_fsl_mc_irq_handler(hwirq, irq);
+	}
+
+	return 0;
+
+unlock:
+	mutex_unlock(&vdev->reflck->lock);
+	return ret;
+
 }
 
 int vfio_fsl_mc_set_irqs_ioctl(struct vfio_fsl_mc_device *vdev,
@@ -32,3 +170,25 @@ int vfio_fsl_mc_set_irqs_ioctl(struct vfio_fsl_mc_device *vdev,
 	else
 		return -EINVAL;
 }
+
+/* Free All IRQs for the given MC object */
+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 or the interrupts
+	 * were not configured
+	 */
+	if (!vdev->mc_irqs)
+		return;
+
+	for (i = 0; i < irq_count; i++)
+		vfio_set_trigger(vdev, i, -1);
+
+	fsl_mc_free_irqs(mc_dev);
+	kfree(vdev->mc_irqs);
+	vdev->mc_irqs = NULL;
+}

drivers/vfio/fsl-mc/vfio_fsl_mc_private.h

@@ -15,6 +15,13 @@
 #define VFIO_FSL_MC_INDEX_TO_OFFSET(index)	\
 	((u64)(index) << VFIO_FSL_MC_OFFSET_SHIFT)
 
+struct vfio_fsl_mc_irq {
+	u32         flags;
+	u32         count;
+	struct eventfd_ctx  *trigger;
+	char            *name;
+};
+
 struct vfio_fsl_mc_reflck {
 	struct kref		kref;
 	struct mutex		lock;
@@ -34,11 +41,14 @@ struct vfio_fsl_mc_device {
 	struct vfio_fsl_mc_region	*regions;
 	struct vfio_fsl_mc_reflck   *reflck;
 	struct mutex         igate;
+	struct vfio_fsl_mc_irq      *mc_irqs;
 };
 
 extern int vfio_fsl_mc_set_irqs_ioctl(struct vfio_fsl_mc_device *vdev,
 			       u32 flags, unsigned int index,
 			       unsigned int start, unsigned int count,
 			       void *data);
 
+void vfio_fsl_mc_irqs_cleanup(struct vfio_fsl_mc_device *vdev);
+
 #endif /* VFIO_FSL_MC_PRIVATE_H */