amdgpu: Add context priority override function.

This way we can override the priority of a single context using a
master fd.

Since we cannot usefully create an amdgpu device of a master fd
without the fd deduplication kicking in this takes a plain fd.

This can be used by e.g. radv to get high priority contexts using
a master fd from the primary node or a lease.

Reviewed-by: Samuel Pitoiset <samuel.pitoiset@gmail.com>
Reviewed-by: Andres Rodriguez <andresx7@gmail.com>
Reviewed-by: Chunming Zhou <david1.zhou@amd.com>

amdgpu/amdgpu-symbol-check

@@ -38,6 +38,7 @@ amdgpu_cs_create_syncobj2
 amdgpu_cs_ctx_create
 amdgpu_cs_ctx_create2
 amdgpu_cs_ctx_free
+amdgpu_cs_ctx_override_priority
 amdgpu_cs_destroy_semaphore
 amdgpu_cs_destroy_syncobj
 amdgpu_cs_export_syncobj

amdgpu/amdgpu.h

@@ -911,6 +911,21 @@ int amdgpu_cs_ctx_create(amdgpu_device_handle dev,
 */
 int amdgpu_cs_ctx_free(amdgpu_context_handle context);
 
+/**
+ * Override the submission priority for the given context using a master fd.
+ *
+ * \param   dev        - \c [in] device handle
+ * \param   context    - \c [in] context handle for context id
+ * \param   master_fd  - \c [in] The master fd to authorize the override.
+ * \param   priority   - \c [in] The priority to assign to the context.
+ *
+ * \return 0 on success or a a negative Posix error code on failure.
+ */
+int amdgpu_cs_ctx_override_priority(amdgpu_device_handle dev,
+                                    amdgpu_context_handle context,
+                                    int master_fd,
+                                    unsigned priority);
+
 /**
  * Query reset state for the specific GPU Context
  *

amdgpu/amdgpu_cs.c

@@ -142,6 +142,31 @@ drm_public int amdgpu_cs_ctx_free(amdgpu_context_handle context)
 	return r;
 }
 
+drm_public int amdgpu_cs_ctx_override_priority(amdgpu_device_handle dev,
+                                               amdgpu_context_handle context,
+                                               int master_fd,
+                                               unsigned priority)
+{
+	int r;
+
+	if (!dev || !context || master_fd < 0)
+		return -EINVAL;
+
+	union drm_amdgpu_sched args;
+	memset(&args, 0, sizeof(args));
+
+	args.in.op = AMDGPU_SCHED_OP_CONTEXT_PRIORITY_OVERRIDE;
+	args.in.fd = dev->fd;
+	args.in.priority = priority;
+	args.in.ctx_id = context->id;
+
+	r = drmCommandWrite(master_fd, DRM_AMDGPU_SCHED, &args, sizeof(args));
+	if (r)
+		return r;
+
+	return 0;
+}
+
 drm_public int amdgpu_cs_query_reset_state(amdgpu_context_handle context,
 					   uint32_t *state, uint32_t *hangs)
 {