vfio/platform: return IRQ info

Return information for the interrupts exposed by the device.
This patch extends VFIO_DEVICE_GET_INFO with the number of IRQs
and enables VFIO_DEVICE_GET_IRQ_INFO.

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>
diff --git a/drivers/vfio/platform/vfio_platform_common.c b/drivers/vfio/platform/vfio_platform_common.c
index d7fe2c7..908d510 100644
--- a/drivers/vfio/platform/vfio_platform_common.c
+++ b/drivers/vfio/platform/vfio_platform_common.c
@@ -101,6 +101,7 @@
 
 	if (!(--vdev->refcnt)) {
 		vfio_platform_regions_cleanup(vdev);
+		vfio_platform_irq_cleanup(vdev);
 	}
 
 	mutex_unlock(&driver_lock);
@@ -122,6 +123,10 @@
 		ret = vfio_platform_regions_init(vdev);
 		if (ret)
 			goto err_reg;
+
+		ret = vfio_platform_irq_init(vdev);
+		if (ret)
+			goto err_irq;
 	}
 
 	vdev->refcnt++;
@@ -129,6 +134,8 @@
 	mutex_unlock(&driver_lock);
 	return 0;
 
+err_irq:
+	vfio_platform_regions_cleanup(vdev);
 err_reg:
 	mutex_unlock(&driver_lock);
 	module_put(THIS_MODULE);
@@ -154,7 +161,7 @@
 
 		info.flags = vdev->flags;
 		info.num_regions = vdev->num_regions;
-		info.num_irqs = 0;
+		info.num_irqs = vdev->num_irqs;
 
 		return copy_to_user((void __user *)arg, &info, minsz);
 
@@ -179,10 +186,26 @@
 
 		return copy_to_user((void __user *)arg, &info, minsz);
 
-	} else if (cmd == VFIO_DEVICE_GET_IRQ_INFO)
-		return -EINVAL;
+	} else if (cmd == VFIO_DEVICE_GET_IRQ_INFO) {
+		struct vfio_irq_info info;
 
-	else if (cmd == VFIO_DEVICE_SET_IRQS)
+		minsz = offsetofend(struct vfio_irq_info, count);
+
+		if (copy_from_user(&info, (void __user *)arg, minsz))
+			return -EFAULT;
+
+		if (info.argsz < minsz)
+			return -EINVAL;
+
+		if (info.index >= vdev->num_irqs)
+			return -EINVAL;
+
+		info.flags = vdev->irqs[info.index].flags;
+		info.count = vdev->irqs[info.index].count;
+
+		return copy_to_user((void __user *)arg, &info, minsz);
+
+	} else if (cmd == VFIO_DEVICE_SET_IRQS)
 		return -EINVAL;
 
 	else if (cmd == VFIO_DEVICE_RESET)