vfio/platform: implement IRQ masking/unmasking via an eventfd

With this patch the VFIO user will be able to set an eventfd that can be
used in order to mask and unmask IRQs of platform devices.
Signed-off-by: Antonios Motakis <a.motakis@virtualopensystems.com>
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

@@ -37,6 +37,15 @@ static void vfio_platform_mask(struct vfio_platform_irq *irq_ctx)
 	spin_unlock_irqrestore(&irq_ctx->lock, flags);
 }
 
+static int vfio_platform_mask_handler(void *opaque, void *unused)
+{
+	struct vfio_platform_irq *irq_ctx = opaque;
+
+	vfio_platform_mask(irq_ctx);
+
+	return 0;
+}
+
 static int vfio_platform_set_irq_mask(struct vfio_platform_device *vdev,
 				      unsigned index, unsigned start,
 				      unsigned count, uint32_t flags,
@@ -48,8 +57,18 @@ static int vfio_platform_set_irq_mask(struct vfio_platform_device *vdev,
 	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_EVENTFD) {
+		int32_t fd = *(int32_t *)data;
+
+		if (fd >= 0)
+			return vfio_virqfd_enable((void *) &vdev->irqs[index],
+						  vfio_platform_mask_handler,
+						  NULL, NULL,
+						  &vdev->irqs[index].mask, fd);
+
+		vfio_virqfd_disable(&vdev->irqs[index].mask);
+		return 0;
+	}
 
 	if (flags & VFIO_IRQ_SET_DATA_NONE) {
 		vfio_platform_mask(&vdev->irqs[index]);
@@ -78,6 +97,15 @@ static void vfio_platform_unmask(struct vfio_platform_irq *irq_ctx)
 	spin_unlock_irqrestore(&irq_ctx->lock, flags);
 }
 
+static int vfio_platform_unmask_handler(void *opaque, void *unused)
+{
+	struct vfio_platform_irq *irq_ctx = opaque;
+
+	vfio_platform_unmask(irq_ctx);
+
+	return 0;
+}
+
 static int vfio_platform_set_irq_unmask(struct vfio_platform_device *vdev,
 					unsigned index, unsigned start,
 					unsigned count, uint32_t flags,
@@ -89,8 +117,19 @@ static int vfio_platform_set_irq_unmask(struct vfio_platform_device *vdev,
 	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_EVENTFD) {
+		int32_t fd = *(int32_t *)data;
+
+		if (fd >= 0)
+			return vfio_virqfd_enable((void *) &vdev->irqs[index],
+						  vfio_platform_unmask_handler,
+						  NULL, NULL,
+						  &vdev->irqs[index].unmask,
+						  fd);
+
+		vfio_virqfd_disable(&vdev->irqs[index].unmask);
+		return 0;
+	}
 
 	if (flags & VFIO_IRQ_SET_DATA_NONE) {
 		vfio_platform_unmask(&vdev->irqs[index]);

drivers/vfio/platform/vfio_platform_private.h

@@ -35,6 +35,8 @@ struct vfio_platform_irq {
 	struct eventfd_ctx	*trigger;
 	bool			masked;
 	spinlock_t		lock;
+	struct virqfd		*unmask;
+	struct virqfd		*mask;
 };
 
 struct vfio_platform_region {