drm/v3d: Size the kperfmon_ids array at runtime

Instead of statically reserving pessimistic space for the kperfmon_ids
array, make the userspace extension code allocate the exactly required
amount of space.

Apart from saving some memory at runtime, this also removes the need for
the V3D_MAX_PERFMONS macro whose removal will benefit further driver
cleanup.
Signed-off-by: Tvrtko Ursulin <tvrtko.ursulin@igalia.com>
Reviewed-by: Maíra Canal <mcanal@igalia.com>
Signed-off-by: Maíra Canal <mcanal@igalia.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20240711135340.84617-8-tursulin@igalia.com

drivers/gpu/drm/v3d/v3d_drv.h

@@ -351,13 +351,9 @@ struct v3d_timestamp_query {
 	struct drm_syncobj *syncobj;
 };
 
-/* Number of perfmons required to handle all supported performance counters */
-#define V3D_MAX_PERFMONS DIV_ROUND_UP(V3D_MAX_COUNTERS, \
-				      DRM_V3D_MAX_PERF_COUNTERS)
-
 struct v3d_performance_query {
 	/* Performance monitor IDs for this query */
-	u32 kperfmon_ids[V3D_MAX_PERFMONS];
+	u32 *kperfmon_ids;
 
 	/* Syncobj that indicates the query availability */
 	struct drm_syncobj *syncobj;

drivers/gpu/drm/v3d/v3d_sched.c

@@ -94,8 +94,10 @@ v3d_performance_query_info_free(struct v3d_performance_query_info *query_info,
 	if (query_info->queries) {
 		unsigned int i;
 
-		for (i = 0; i < count; i++)
+		for (i = 0; i < count; i++) {
 			drm_syncobj_put(query_info->queries[i].syncobj);
+			kvfree(query_info->queries[i].kperfmon_ids);
+		}
 
 		kvfree(query_info->queries);
 	}

drivers/gpu/drm/v3d/v3d_submit.c

@@ -671,10 +671,20 @@ v3d_copy_query_info(struct v3d_performance_query_info *query_info,
 			goto error;
 		}
 
+		query->kperfmon_ids =
+			kvmalloc_array(nperfmons,
+				       sizeof(struct v3d_performance_query *),
+				       GFP_KERNEL);
+		if (!query->kperfmon_ids) {
+			err = -ENOMEM;
+			goto error;
+		}
+
 		ids_pointer = u64_to_user_ptr(ids);
 
 		for (j = 0; j < nperfmons; j++) {
 			if (get_user(id, ids_pointer++)) {
+				kvfree(query->kperfmon_ids);
 				err = -EFAULT;
 				goto error;
 			}
@@ -684,6 +694,7 @@ v3d_copy_query_info(struct v3d_performance_query_info *query_info,
 
 		query->syncobj = drm_syncobj_find(file_priv, sync);
 		if (!query->syncobj) {
+			kvfree(query->kperfmon_ids);
 			err = -ENOENT;
 			goto error;
 		}
@@ -717,9 +728,6 @@ v3d_get_cpu_reset_performance_params(struct drm_file *file_priv,
 	if (copy_from_user(&reset, ext, sizeof(reset)))
 		return -EFAULT;
 
-	if (reset.nperfmons > V3D_MAX_PERFMONS)
-		return -EINVAL;
-
 	job->job_type = V3D_CPU_JOB_TYPE_RESET_PERFORMANCE_QUERY;
 
 	job->performance_query.queries = kvmalloc_array(reset.count,
@@ -767,9 +775,6 @@ v3d_get_cpu_copy_performance_query_params(struct drm_file *file_priv,
 	if (copy.pad)
 		return -EINVAL;
 
-	if (copy.nperfmons > V3D_MAX_PERFMONS)
-		return -EINVAL;
-
 	job->job_type = V3D_CPU_JOB_TYPE_COPY_PERFORMANCE_QUERY;
 
 	job->performance_query.queries = kvmalloc_array(copy.count,