[Intel-gfx] [PATCH v3 3/7] drm/i915: introduce a mechanism to extend execbuf2

[Lionel Landwerlin]

We're planning to use this for a couple of new feature where we need
to provide additional parameters to execbuf.

Signed-off-by: Lionel Landwerlin <lionel.g.landwerlin at intel.com>
---
 .../gpu/drm/i915/gem/i915_gem_execbuffer.c    | 49 ++++++++++++++++++-
 include/uapi/drm/i915_drm.h                   | 44 +++++++++++++++--
 2 files changed, 89 insertions(+), 4 deletions(-)

diff --git a/drivers/gpu/drm/i915/gem/i915_gem_execbuffer.c b/drivers/gpu/drm/i915/gem/i915_gem_execbuffer.c
index ed522fdfbe7f..480e20043d80 100644
--- a/drivers/gpu/drm/i915/gem/i915_gem_execbuffer.c
+++ b/drivers/gpu/drm/i915/gem/i915_gem_execbuffer.c
@@ -269,6 +269,10 @@ struct i915_execbuffer {
 	 */
 	int lut_size;
 	struct hlist_head *buckets; /** ht for relocation handles */
+
+	struct {
+		u64 flags; /** Available extensions parameters */
+	} extensions;
 };
 
 #define exec_entry(EB, VMA) (&(EB)->exec[(VMA)->exec_flags - (EB)->flags])
@@ -1958,7 +1962,7 @@ static bool i915_gem_check_execbuffer(struct drm_i915_gem_execbuffer2 *exec)
 		return false;
 
 	/* Kernel clipping was a DRI1 misfeature */
-	if (!(exec->flags & I915_EXEC_FENCE_ARRAY)) {
+	if (!(exec->flags & (I915_EXEC_FENCE_ARRAY | I915_EXEC_EXT))) {
 		if (exec->num_cliprects || exec->cliprects_ptr)
 			return false;
 	}
@@ -2336,6 +2340,42 @@ signal_fence_array(struct i915_execbuffer *eb,
 	}
 }
 
+static int
+parse_execbuf2_extensions(struct drm_i915_gem_execbuffer2 *args,
+			  struct i915_execbuffer *eb)
+{
+	u64 iter_ptr = args->cliprects_ptr;
+
+	if (args->num_cliprects != 0)
+		return -EINVAL;
+
+	while (iter_ptr != 0) {
+		struct drm_i915_gem_base_execbuffer_ext iter;
+
+		if (copy_from_user(&iter,
+				   u64_to_user_ptr(iter_ptr), sizeof(iter)))
+			return -EFAULT;
+
+		if (iter.pad)
+			return -EINVAL;
+
+		/* Specifying the same extension multiple times is invalid. */
+		if (eb->extensions.flags & BIT(iter.type))
+			return -EINVAL;
+
+		switch (iter.type) {
+		default:
+			return -EINVAL;
+		}
+
+		eb->extensions.flags |= BIT(iter.type);
+
+		iter_ptr = iter.next_ptr;
+	}
+
+	return 0;
+}
+
 static int
 i915_gem_do_execbuffer(struct drm_device *dev,
 		       struct drm_file *file,
@@ -2382,6 +2422,13 @@ i915_gem_do_execbuffer(struct drm_device *dev,
 	if (args->flags & I915_EXEC_IS_PINNED)
 		eb.batch_flags |= I915_DISPATCH_PINNED;
 
+	eb.extensions.flags = 0;
+	if (args->flags & I915_EXEC_EXT) {
+		err = parse_execbuf2_extensions(args, &eb);
+		if (err)
+			return err;
+	}
+
 	if (args->flags & I915_EXEC_FENCE_IN) {
 		in_fence = sync_file_get_fence(lower_32_bits(args->rsvd2));
 		if (!in_fence)
diff --git a/include/uapi/drm/i915_drm.h b/include/uapi/drm/i915_drm.h
index e27a8eda9121..2ef5ab0daae4 100644
--- a/include/uapi/drm/i915_drm.h
+++ b/include/uapi/drm/i915_drm.h
@@ -1013,6 +1013,29 @@ struct drm_i915_gem_exec_fence {
 	__u32 flags;
 };
 
+enum drm_i915_gem_base_execbuffer_type {
+	DRM_I915_GEM_BASE_EXECBUFFER_TYPE_MAX /* non-ABI */
+};
+
+struct drm_i915_gem_base_execbuffer_ext {
+	/**
+	 * Type of the extension node as limited in enum
+	 * drm_i915_gem_base_execbuffer_type.
+	 */
+	__u32 type;
+
+	/**
+	 * Unused for now. Must be cleared to zero.
+	 */
+	__u32 pad;
+
+	/**
+	 * Pointer to another struct drm_i915_gem_base_execbuffer_ext or NULL
+	 * to terminate the chain.
+	 */
+	__u64 next_ptr;
+};
+
 struct drm_i915_gem_execbuffer2 {
 	/**
 	 * List of gem_exec_object2 structs
@@ -1029,8 +1052,14 @@ struct drm_i915_gem_execbuffer2 {
 	__u32 num_cliprects;
 	/**
 	 * This is a struct drm_clip_rect *cliprects if I915_EXEC_FENCE_ARRAY
-	 * is not set.  If I915_EXEC_FENCE_ARRAY is set, then this is a
-	 * struct drm_i915_gem_exec_fence *fences.
+	 * & I915_EXEC_EXT are not set.
+	 *
+	 * If I915_EXEC_FENCE_ARRAY is set, then this is a pointer to an array
+	 * of struct drm_i915_gem_exec_fence and num_cliprects is the length
+	 * of the array.
+	 *
+	 * If I915_EXEC_EXT is set, then this is a pointer to a single struct
+	 * drm_i915_gem_base_execbuffer_ext and num_cliprects is 0.
 	 */
 	__u64 cliprects_ptr;
 #define I915_EXEC_RING_MASK              (0x3f)
@@ -1148,7 +1177,16 @@ struct drm_i915_gem_execbuffer2 {
  */
 #define I915_EXEC_FENCE_SUBMIT		(1 << 20)
 
-#define __I915_EXEC_UNKNOWN_FLAGS (-(I915_EXEC_FENCE_SUBMIT << 1))
+/*
+ * Setting I915_EXEC_EXT implies that drm_i915_gem_execbuffer2.cliprects_ptr
+ * is treated as a pointer to an linked list of
+ * drm_i915_gem_base_execbuffer_ext. Each drm_i915_gem_base_execbuffer_ext
+ * node is the base of a larger structure. The list of supported structures
+ * are listed in the drm_i915_gem_base_execbuffer_type enum.
+ */
+#define I915_EXEC_EXT		(1 << 21)
+
+#define __I915_EXEC_UNKNOWN_FLAGS (-(I915_EXEC_EXT<<1))
 
 #define I915_EXEC_CONTEXT_ID_MASK	(0xffffffff)
 #define i915_execbuffer2_set_context_id(eb2, context) \
-- 
2.21.0.392.gf8f6787159e