[PATCH 5/5] drm: Add four ioctls for managing drm mode object leases [v6]

[Keith Packard]

drm_mode_create_lease

	Creates a lease for a list of drm mode objects, returning an
	fd for the new drm_master and a 64-bit identifier for the lessee

drm_mode_list_lesees

	List the identifiers of the lessees for a master file

drm_mode_get_lease

	List the leased objects for a master file

drm_mode_revoke_lease

	Erase the set of objects managed by a lease.

This should suffice to at least create and query leases.

Changes for v2 as suggested by Daniel Vetter <daniel.vetter@xxxxxxxx>:

 * query ioctls only query the master associated with
   the provided file.

 * 'mask_lease' value has been removed

 * change ioctl has been removed.

Changes for v3 suggested in part by Dave Airlie <airlied@xxxxxxxxx>

 * Add revoke ioctl.

Changes for v4 suggested by Dave Airlie <airlied@xxxxxxxxx>

 * Expand on the comment about the magic use of &drm_lease_idr_object
 * Pad lease ioctl structures to align on 64-bit boundaries

Changes for v5 suggested by Dave Airlie <airlied@xxxxxxxxx>

 * Check for non-negative object_id in create_lease to avoid debug
   output from the kernel.

Changes for v5 provided by Dave Airlie <airlied@xxxxxxxxx>

 * For non-universal planes add primary/cursor planes to lease

   If we aren't exposing universal planes to this userspace client,
   and it requests a lease on a crtc, we should implicitly export the
   primary and cursor planes for the crtc.

   If the lessee doesn't request universal planes, it will just see
   the crtc, but if it does request them it will then see the plane
   objects as well.

   This also moves the object look ups earlier as a side effect, so
   we'd exit the ioctl quicker for non-existant objects.

 * Restrict leases to crtc/connector/planes.

   This only allows leasing for objects we wish to allow.

Signed-off-by: Keith Packard <keithp@xxxxxxxxxx>
Signed-off-by: Dave Airlie <airlied@xxxxxxxxxx>
---
 drivers/gpu/drm/drm_ioctl.c       |   4 +
 drivers/gpu/drm/drm_lease.c       | 318 ++++++++++++++++++++++++++++++++++++++
 drivers/gpu/drm/drm_mode_object.c |   5 +-
 include/drm/drm_lease.h           |  12 ++
 include/drm/drm_mode_object.h     |   2 +
 include/uapi/drm/drm.h            |   5 +
 include/uapi/drm/drm_mode.h       |  66 ++++++++
 7 files changed, 410 insertions(+), 2 deletions(-)

diff --git a/drivers/gpu/drm/drm_ioctl.c b/drivers/gpu/drm/drm_ioctl.c
index 9c435a4c0c82..4aafe4802099 100644
--- a/drivers/gpu/drm/drm_ioctl.c
+++ b/drivers/gpu/drm/drm_ioctl.c
@@ -665,6 +665,10 @@ static const struct drm_ioctl_desc drm_ioctls[] = {
 		      DRM_UNLOCKED|DRM_RENDER_ALLOW),
 	DRM_IOCTL_DEF(DRM_IOCTL_CRTC_GET_SEQUENCE, drm_crtc_get_sequence_ioctl, DRM_UNLOCKED),
 	DRM_IOCTL_DEF(DRM_IOCTL_CRTC_QUEUE_SEQUENCE, drm_crtc_queue_sequence_ioctl, DRM_UNLOCKED),
+	DRM_IOCTL_DEF(DRM_IOCTL_MODE_CREATE_LEASE, drm_mode_create_lease_ioctl, DRM_MASTER|DRM_CONTROL_ALLOW|DRM_UNLOCKED),
+	DRM_IOCTL_DEF(DRM_IOCTL_MODE_LIST_LESSEES, drm_mode_list_lessees_ioctl, DRM_MASTER|DRM_CONTROL_ALLOW|DRM_UNLOCKED),
+	DRM_IOCTL_DEF(DRM_IOCTL_MODE_GET_LEASE, drm_mode_get_lease_ioctl, DRM_MASTER|DRM_CONTROL_ALLOW|DRM_UNLOCKED),
+	DRM_IOCTL_DEF(DRM_IOCTL_MODE_REVOKE_LEASE, drm_mode_revoke_lease_ioctl, DRM_MASTER|DRM_CONTROL_ALLOW|DRM_UNLOCKED),
 };
 
 #define DRM_CORE_IOCTL_COUNT	ARRAY_SIZE( drm_ioctls )
diff --git a/drivers/gpu/drm/drm_lease.c b/drivers/gpu/drm/drm_lease.c
index 6c3f2445254c..88c213f9c4ab 100644
--- a/drivers/gpu/drm/drm_lease.c
+++ b/drivers/gpu/drm/drm_lease.c
@@ -23,6 +23,8 @@
 #define drm_for_each_lessee(lessee, lessor) \
 	list_for_each_entry((lessee), &(lessor)->lessees, lessee_list)
 
+static uint64_t drm_lease_idr_object;
+
 /**
  * drm_lease_owner - return ancestor owner drm_master
  * @master: drm_master somewhere within tree of lessees and lessors
@@ -337,3 +339,319 @@ void _drm_lease_revoke(struct drm_master *top)
 		}
 	}
 }
+
+/**
+ * drm_mode_create_lease_ioctl - create a new lease
+ * @dev: the drm device
+ * @data: pointer to struct drm_mode_create_lease
+ * @file_priv: the file being manipulated
+ *
+ * The master associated with the specified file will have a lease
+ * created containing the objects specified in the ioctl structure.
+ * A file descriptor will be allocated for that and returned to the
+ * application.
+ */
+int drm_mode_create_lease_ioctl(struct drm_device *dev,
+				void *data, struct drm_file *lessor_priv)
+{
+	struct drm_mode_create_lease *cl = data;
+	size_t object_count;
+	size_t o;
+	int ret = 0;
+	struct idr leases;
+	struct drm_master *lessor = lessor_priv->master;
+	struct drm_master *lessee = NULL;
+	struct file *lessee_file = NULL;
+	struct file *lessor_file = lessor_priv->filp;
+	struct drm_file *lessee_priv;
+	int fd = -1;
+
+	/* Do not allow sub-leases */
+	if (lessor->lessor)
+		return -EINVAL;
+
+	object_count = cl->object_count;
+	idr_init(&leases);
+
+	/* Allocate a file descriptor for the lease */
+	fd = get_unused_fd_flags(cl->flags & (O_CLOEXEC | O_NONBLOCK));
+
+	DRM_DEBUG_LEASE("Creating new lease\n");
+
+	/* Lookup the mode objects and add their IDs to the lease request */
+	for (o = 0; o < object_count; o++) {
+		__u32 object_id;
+		struct drm_mode_object *obj;
+
+		if (copy_from_user(&object_id,
+				   u64_to_user_ptr(cl->object_ids) + o * sizeof (__u32),
+				   sizeof (__u32))) {
+			ret = -EFAULT;
+			goto out_leases;
+		}
+		DRM_DEBUG_LEASE("Adding object %d to lease\n", object_id);
+
+		if ((int) object_id < 0) {
+			ret = -EINVAL;
+			goto out_leases;
+		}
+
+		obj = drm_mode_object_find(dev, lessor_priv, object_id,
+					   DRM_MODE_OBJECT_ANY);
+		if (!obj) {
+			ret = -ENOENT;
+			goto out_leases;
+		}
+
+		/* only allow leasing on crtc/plane/connector objects */
+		if (!drm_mode_object_lease_required(obj->type)) {
+			ret = -EINVAL;
+			drm_mode_object_put(obj);
+			goto out_leases;
+		}
+
+		/*
+		 * We're using an IDR to hold the set of leased
+		 * objects, but we don't need to point at the object's
+		 * data structure from the lease as the main crtc_idr
+		 * will be used to actually find that. Instead, all we
+		 * really want is a 'leased/not-leased' result, for
+		 * which any non-NULL pointer will work fine.
+		 */
+		ret = idr_alloc(&leases, &drm_lease_idr_object , object_id, object_id + 1, GFP_KERNEL);
+		if (ret < 0) {
+			DRM_DEBUG_LEASE("Object %d cannot be inserted into leases (%d)\n",
+					object_id, ret);
+			drm_mode_object_put(obj);
+			goto out_leases;
+		}
+		if (obj->type == DRM_MODE_OBJECT_CRTC && !lessor_priv->universal_planes) {
+			struct drm_crtc *crtc = obj_to_crtc(obj);
+			ret = idr_alloc(&leases, &drm_lease_idr_object, crtc->primary->base.id, crtc->primary->base.id + 1, GFP_KERNEL);
+			if (ret < 0) {
+				DRM_DEBUG_LEASE("Object primary plane %d cannot be inserted into leases (%d)\n",
+						object_id, ret);
+				drm_mode_object_put(obj);
+				goto out_leases;
+			}
+			if (crtc->cursor) {
+				ret = idr_alloc(&leases, &drm_lease_idr_object, crtc->cursor->base.id, crtc->cursor->base.id + 1, GFP_KERNEL);
+				if (ret < 0) {
+					DRM_DEBUG_LEASE("Object cursor plane %d cannot be inserted into leases (%d)\n",
+							object_id, ret);
+					drm_mode_object_put(obj);
+					goto out_leases;
+				}
+			}
+		}
+		drm_mode_object_put(obj);
+	}
+
+	mutex_lock(&dev->master_mutex);
+
+	DRM_DEBUG_LEASE("Creating lease\n");
+	lessee = drm_lease_create(lessor, &leases);
+
+	if (IS_ERR(lessee)) {
+		ret = PTR_ERR(lessee);
+		mutex_unlock(&dev->master_mutex);
+		goto out_leases;
+	}
+
+	/* Clone the lessor file to create a new file for us */
+	DRM_DEBUG_LEASE("Allocating lease file\n");
+	path_get(&lessor_file->f_path);
+	lessee_file = alloc_file(&lessor_file->f_path,
+				 lessor_file->f_mode,
+				 fops_get(lessor_file->f_inode->i_fop));
+	mutex_unlock(&dev->master_mutex);
+
+	if (IS_ERR(lessee_file)) {
+		ret = PTR_ERR(lessee_file);
+		goto out_lessee;
+	}
+
+	/* Initialize the new file for DRM */
+	DRM_DEBUG_LEASE("Initializing the file with %p\n", lessee_file->f_op->open);
+	ret = lessee_file->f_op->open(lessee_file->f_inode, lessee_file);
+	if (ret)
+		goto out_lessee_file;
+
+	lessee_priv = lessee_file->private_data;
+
+	/* Change the file to a master one */
+	drm_master_put(&lessee_priv->master);
+	lessee_priv->master = lessee;
+	lessee_priv->is_master = 1;
+	lessee_priv->authenticated = 1;
+
+	/* Hook up the fd */
+	fd_install(fd, lessee_file);
+
+	/* Pass fd back to userspace */
+	DRM_DEBUG_LEASE("Returning fd %d id %d\n", fd, lessee->lessee_id);
+	cl->fd = fd;
+	cl->lessee_id = lessee->lessee_id;
+
+	DRM_DEBUG_LEASE("drm_mode_create_lease_ioctl succeeded\n");
+	return 0;
+
+out_lessee_file:
+	fput(lessee_file);
+
+out_lessee:
+	drm_master_put(&lessee);
+
+out_leases:
+	idr_destroy(&leases);
+	put_unused_fd(fd);
+
+	DRM_DEBUG_LEASE("drm_mode_create_lease_ioctl failed: %d\n", ret);
+	return ret;
+}
+
+/**
+ * drm_mode_list_lessees_ioctl - list lessee ids
+ * @dev: the drm device
+ * @data: pointer to struct drm_mode_list_lessees
+ * @lessor_priv: the file being manipulated
+ *
+ * Starting from the master associated with the specified file,
+ * the master with the provided lessee_id is found, and then
+ * an array of lessee ids associated with leases from that master
+ * are returned.
+ */
+
+int drm_mode_list_lessees_ioctl(struct drm_device *dev,
+			       void *data, struct drm_file *lessor_priv)
+{
+	struct drm_mode_list_lessees *arg = data;
+	__u32 __user *lessee_ids = (__u32 __user *) (uintptr_t) (arg->lessees_ptr);
+	__u32 count_lessees = arg->count_lessees;
+	struct drm_master *lessor = lessor_priv->master, *lessee;
+	int count;
+	int ret = 0;
+
+	DRM_DEBUG_LEASE("List lessees for %d\n", lessor->lessee_id);
+
+	mutex_lock(&dev->master_mutex);
+
+	count = 0;
+	drm_for_each_lessee(lessee, lessor) {
+		/* Only list un-revoked leases */
+		if (!idr_is_empty(&lessee->leases)) {
+			if (count_lessees > count) {
+				DRM_DEBUG_LEASE("Add lessee %d\n", lessee->lessee_id);
+				ret = put_user(lessee->lessee_id, lessee_ids + count);
+				if (ret)
+					break;
+			}
+			count++;
+		}
+	}
+
+	DRM_DEBUG_LEASE("Lessor leases to %d\n", count);
+	if (ret == 0)
+		arg->count_lessees = count;
+
+	mutex_unlock(&dev->master_mutex);
+
+	return ret;
+}
+
+/**
+ * drm_mode_get_lease_ioctl - list leased objects
+ * @dev: the drm device
+ * @data: pointer to struct drm_mode_get_lease
+ * @file_priv: the file being manipulated
+ *
+ * Return the list of leased objects for the specified lessee
+ */
+
+int drm_mode_get_lease_ioctl(struct drm_device *dev,
+			     void *data, struct drm_file *lessee_priv)
+{
+	struct drm_mode_get_lease *arg = data;
+	__u32 __user *object_ids = (__u32 __user *) (uintptr_t) (arg->objects_ptr);
+	__u32 count_objects = arg->count_objects;
+	struct drm_master *lessee = lessee_priv->master;
+	struct idr *object_idr;
+	int count;
+	void *entry;
+	int object;
+	int ret = 0;
+
+	DRM_DEBUG_LEASE("get lease for %d\n", lessee->lessee_id);
+
+	mutex_lock(&dev->master_mutex);
+
+	if (lessee->lessor == NULL)
+		/* owner can use all objects */
+		object_idr = &lessee->dev->mode_config.crtc_idr;
+	else
+		/* lessee can only use allowed object */
+		object_idr = &lessee->leases;
+
+	count = 0;
+	idr_for_each_entry(object_idr, entry, object) {
+		if (count_objects > count) {
+			DRM_DEBUG_LEASE("adding object %d\n", object);
+			ret = put_user(object, object_ids + count);
+			if (ret)
+				break;
+		}
+		count++;
+	}
+
+	DRM_DEBUG("lease holds %d objects\n", count);
+	if (ret == 0)
+		arg->count_objects = count;
+
+	mutex_unlock(&dev->master_mutex);
+
+	return ret;
+}
+
+/**
+ * drm_mode_revoke_lease_ioctl - revoke lease
+ * @dev: the drm device
+ * @data: pointer to struct drm_mode_revoke_lease
+ * @file_priv: the file being manipulated
+ *
+ * This removes all of the objects from the lease without
+ * actually getting rid of the lease itself; that way all
+ * references to it still work correctly
+ */
+int drm_mode_revoke_lease_ioctl(struct drm_device *dev,
+				void *data, struct drm_file *lessor_priv)
+{
+	struct drm_mode_revoke_lease *arg = data;
+	struct drm_master *lessor = lessor_priv->master;
+	struct drm_master *lessee;
+	int ret = 0;
+
+	DRM_DEBUG_LEASE("revoke lease for %d\n", arg->lessee_id);
+
+	mutex_lock(&dev->master_mutex);
+
+	lessee = _drm_find_lessee(lessor, arg->lessee_id);
+
+	/* No such lessee */
+	if (!lessee) {
+		ret = -ENOENT;
+		goto fail;
+	}
+
+	/* Lease is not held by lessor */
+	if (lessee->lessor != lessor) {
+		ret = -EACCES;
+		goto fail;
+	}
+
+	_drm_lease_revoke(lessee);
+
+fail:
+	mutex_unlock(&dev->master_mutex);
+
+	return ret;
+}
diff --git a/drivers/gpu/drm/drm_mode_object.c b/drivers/gpu/drm/drm_mode_object.c
index d1599f36b605..7c8b2698c6a7 100644
--- a/drivers/gpu/drm/drm_mode_object.c
+++ b/drivers/gpu/drm/drm_mode_object.c
@@ -111,7 +111,7 @@ void drm_mode_object_unregister(struct drm_device *dev,
  * Returns whether the provided type of drm_mode_object must
  * be owned or leased to be used by a process.
  */
-static bool drm_lease_required(uint32_t type)
+bool drm_mode_object_lease_required(uint32_t type)
 {
 	switch(type) {
 	case DRM_MODE_OBJECT_CRTC:
@@ -136,7 +136,8 @@ struct drm_mode_object *__drm_mode_object_find(struct drm_device *dev,
 	if (obj && obj->id != id)
 		obj = NULL;
 
-	if (obj && drm_lease_required(obj->type) && !_drm_lease_held(file_priv, obj->id))
+	if (obj && drm_mode_object_lease_required(obj->type) &&
+	    !_drm_lease_held(file_priv, obj->id))
 		obj = NULL;
 
 	if (obj && obj->free_cb) {
diff --git a/include/drm/drm_lease.h b/include/drm/drm_lease.h
index 0981631b9aed..d2bcd1ea6cdc 100644
--- a/include/drm/drm_lease.h
+++ b/include/drm/drm_lease.h
@@ -31,4 +31,16 @@ void _drm_lease_revoke(struct drm_master *master);
 
 uint32_t drm_lease_filter_crtcs(struct drm_file *file_priv, uint32_t crtcs);
 
+int drm_mode_create_lease_ioctl(struct drm_device *dev,
+				void *data, struct drm_file *file_priv);
+
+int drm_mode_list_lessees_ioctl(struct drm_device *dev,
+				void *data, struct drm_file *file_priv);
+
+int drm_mode_get_lease_ioctl(struct drm_device *dev,
+			     void *data, struct drm_file *file_priv);
+
+int drm_mode_revoke_lease_ioctl(struct drm_device *dev,
+				void *data, struct drm_file *file_priv);
+
 #endif /* _DRM_LEASE_H_ */
diff --git a/include/drm/drm_mode_object.h b/include/drm/drm_mode_object.h
index c8155cb5a932..7ba3913f30b5 100644
--- a/include/drm/drm_mode_object.h
+++ b/include/drm/drm_mode_object.h
@@ -154,4 +154,6 @@ int drm_object_property_get_value(struct drm_mode_object *obj,
 void drm_object_attach_property(struct drm_mode_object *obj,
 				struct drm_property *property,
 				uint64_t init_val);
+
+bool drm_mode_object_lease_required(uint32_t type);
 #endif
diff --git a/include/uapi/drm/drm.h b/include/uapi/drm/drm.h
index a106f6a7a0f9..9c02d2125d07 100644
--- a/include/uapi/drm/drm.h
+++ b/include/uapi/drm/drm.h
@@ -888,6 +888,11 @@ extern "C" {
 #define DRM_IOCTL_SYNCOBJ_RESET		DRM_IOWR(0xC4, struct drm_syncobj_array)
 #define DRM_IOCTL_SYNCOBJ_SIGNAL	DRM_IOWR(0xC5, struct drm_syncobj_array)
 
+#define DRM_IOCTL_MODE_CREATE_LEASE	DRM_IOWR(0xC6, struct drm_mode_create_lease)
+#define DRM_IOCTL_MODE_LIST_LESSEES	DRM_IOWR(0xC7, struct drm_mode_list_lessees)
+#define DRM_IOCTL_MODE_GET_LEASE	DRM_IOWR(0xC8, struct drm_mode_get_lease)
+#define DRM_IOCTL_MODE_REVOKE_LEASE	DRM_IOWR(0xC9, struct drm_mode_revoke_lease)
+
 /**
  * Device specific ioctls should only be in their respective headers
  * The device specific ioctl range is from 0x40 to 0x9f.
diff --git a/include/uapi/drm/drm_mode.h b/include/uapi/drm/drm_mode.h
index 34b6bb34b002..5597a87154e5 100644
--- a/include/uapi/drm/drm_mode.h
+++ b/include/uapi/drm/drm_mode.h
@@ -782,6 +782,72 @@ struct drm_mode_destroy_blob {
 	__u32 blob_id;
 };
 
+/**
+ * Lease mode resources, creating another drm_master.
+ */
+struct drm_mode_create_lease {
+	/** Pointer to array of object ids (__u32) */
+	__u64 object_ids;
+	/** Number of object ids */
+	__u32 object_count;
+	/** flags for new FD (O_CLOEXEC, etc) */
+	__u32 flags;
+
+	/** Return: unique identifier for lessee. */
+	__u32 lessee_id;
+	/** Return: file descriptor to new drm_master file */
+	__u32 fd;
+};
+
+/**
+ * List lesses from a drm_master
+ */
+struct drm_mode_list_lessees {
+	/** Number of lessees.
+	 * On input, provides length of the array.
+	 * On output, provides total number. No
+	 * more than the input number will be written
+	 * back, so two calls can be used to get
+	 * the size and then the data.
+	 */
+	__u32 count_lessees;
+	__u32 pad;
+
+	/** Pointer to lessees.
+	 * pointer to __u64 array of lessee ids
+	 */
+	__u64 lessees_ptr;
+};
+
+/**
+ * Get leased objects
+ */
+struct drm_mode_get_lease {
+	/** Number of leased objects.
+	 * On input, provides length of the array.
+	 * On output, provides total number. No
+	 * more than the input number will be written
+	 * back, so two calls can be used to get
+	 * the size and then the data.
+	 */
+	__u32 count_objects;
+	__u32 pad;
+
+	/** Pointer to objects.
+	 * pointer to __u32 array of object ids
+	 */
+	__u64 objects_ptr;
+};
+
+/**
+ * Revoke lease
+ */
+struct drm_mode_revoke_lease {
+	/** Unique ID of lessee
+	 */
+	__u32 lessee_id;
+};
+
 #if defined(__cplusplus)
 }
 #endif
-- 
2.15.0.rc0