drm/gpuvm: Add a flags field to drm_gpuva_op_map

drm_gpuva objects have a flags field. Currently, this can be managed by
drivers out-of-band, without any special handling in drm_gpuvm.

To be able to introduce flags that do affect the logic in the drm_gpuvm
core, we need to plumb it through the map calls. This will allow the
core to check the flags on map and alter the merge/split logic depending
on the requested flags and the flags of the existing drm_gpuva ranges
that are being split.

Signed-off-by: Asahi Lina <lina+kernel@asahilina.net>
Signed-off-by: Caterina Shablia <caterina.shablia@collabora.com>

Author: Caterina Shablia

drivers/gpu/drm/drm_gpuvm.c

@@ -2172,6 +2172,14 @@ op_unmap_cb(const struct drm_gpuvm_ops *fn, void *priv,
 	return fn->sm_step_unmap(&op, priv);
 }
 
+static bool can_merge_flags(struct drm_gpuvm *gpuvm, enum drm_gpuva_flags a,
+			    enum drm_gpuva_flags b)
+{
+	if (gpuvm->ops->sm_can_merge_flags)
+		return gpuvm->ops->sm_can_merge_flags(a, b);
+	return a == b;
+}
+
 static bool __can_merge(struct drm_gpuvm *gpuvm, const struct drm_gpuva_op_map *a,
 			const struct drm_gpuva_op_map *b)
 {
@@ -2181,6 +2189,9 @@ static bool __can_merge(struct drm_gpuvm *gpuvm, const struct drm_gpuva_op_map *
 	if (a->gem.obj != b->gem.obj || !a->gem.obj)
 		return false;
 
+	if (can_merge_flags(gpuvm, a->flags, b->flags))
+		return false;
+
 	/* Order VAs for the rest of the checks. */
 	if (a->va.addr > b->va.addr)
 		swap(a, b);
@@ -2205,6 +2216,7 @@ static bool can_merge(struct drm_gpuvm *gpuvm, const struct drm_gpuva *a,
 		.va.range = a->va.range,
 		.gem.offset = a->gem.offset,
 		.gem.obj = a->gem.obj,
+		.flags = a->flags,
 	};
 
 	return __can_merge(gpuvm, &tmp, b);
@@ -2263,6 +2275,7 @@ __drm_gpuvm_sm_map(struct drm_gpuvm *gpuvm,
 					.va.range = range - req_range,
 					.gem.obj = obj,
 					.gem.offset = offset + req_range,
+					.flags = va->flags,
 				};
 				struct drm_gpuva_op_unmap u = {
 					.va = va,
@@ -2284,6 +2297,7 @@ __drm_gpuvm_sm_map(struct drm_gpuvm *gpuvm,
 				.va.range = ls_range,
 				.gem.obj = obj,
 				.gem.offset = offset,
+				.flags = va->flags,
 			};
 			struct drm_gpuva_op_unmap u = { .va = va };
 
@@ -2327,6 +2341,7 @@ __drm_gpuvm_sm_map(struct drm_gpuvm *gpuvm,
 					.gem.obj = obj,
 					.gem.offset = offset + ls_range +
 						      req_range,
+					.flags = va->flags,
 				};
 
 				ret = op_remap_cb(ops, priv, &p, &n, &u);
@@ -2364,6 +2379,7 @@ __drm_gpuvm_sm_map(struct drm_gpuvm *gpuvm,
 					.va.range = end - req_end,
 					.gem.obj = obj,
 					.gem.offset = offset + req_end - addr,
+					.flags = va->flags,
 				};
 				struct drm_gpuva_op_unmap u = {
 					.va = va,
@@ -2415,6 +2431,7 @@ __drm_gpuvm_sm_unmap(struct drm_gpuvm *gpuvm,
 			prev.va.range = req_addr - addr;
 			prev.gem.obj = obj;
 			prev.gem.offset = offset;
+			prev.flags = va->flags;
 
 			prev_split = true;
 		}
@@ -2424,6 +2441,7 @@ __drm_gpuvm_sm_unmap(struct drm_gpuvm *gpuvm,
 			next.va.range = end - req_end;
 			next.gem.obj = obj;
 			next.gem.offset = offset + (req_end - addr);
+			next.flags = va->flags;
 
 			next_split = true;
 		}

include/drm/drm_gpuvm.h

@@ -871,6 +871,11 @@ struct drm_gpuva_op_map {
 		 */
 		struct drm_gem_object *obj;
 	} gem;
+
+	/**
+	 * @flags: requested flags for the &drm_gpuva for this mapping
+	 */
+	enum drm_gpuva_flags flags;
 };
 
 /**
@@ -1107,6 +1112,7 @@ void drm_gpuva_ops_free(struct drm_gpuvm *gpuvm,
 static inline void drm_gpuva_init_from_op(struct drm_gpuva *va,
 					  struct drm_gpuva_op_map *op)
 {
+	va->flags = op->flags;
 	va->va.addr = op->va.addr;
 	va->va.range = op->va.range;
 	va->gem.obj = op->gem.obj;
@@ -1232,6 +1238,16 @@ struct drm_gpuvm_ops {
 	 * used.
 	 */
 	int (*sm_step_unmap)(struct drm_gpuva_op *op, void *priv);
+
+	/**
+	 * @sm_can_merge_flags: called during &drm_gpuvm_sm_map
+	 *
+	 * This callback is called to determine whether two va ranges can be merged,
+	 * based on their flags.
+	 *
+	 * If NULL, va ranges can only be merged if their flags are equal.
+	 */
+	bool (*sm_can_merge_flags)(enum drm_gpuva_flags a, enum drm_gpuva_flags b);
 };
 
 int drm_gpuvm_sm_map(struct drm_gpuvm *gpuvm, void *priv,