drm/amdgpu: add interface for editing a foreign process's priority v3

The AMDGPU_SCHED_OP_PROCESS_PRIORITY_OVERRIDE ioctls are used to set
the priority of a different process in the current system.

When a request is dropped, the process's contexts will be
restored to the priority specified at context creation time.

A request can be dropped by setting the override priority to
AMDGPU_CTX_PRIORITY_UNSET.

An fd is used to identify the remote process. This is simpler than
passing a pid number, which is vulnerable to re-use, etc.

This functionality is limited to DRM_MASTER since abuse of this
interface can have a negative impact on the system's performance.

v2: removed unused output structure
v3: change refcounted interface for a regular set operation

Signed-off-by: Andres Rodriguez <andresx7@gmail.com>
Acked-by: Christian König <christian.koenig@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

1 files changed, 109 insertions, 0 deletions

diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_sched.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_sched.c
new file mode 100644
index 000000000000..cd123306eda7
--- /dev/null
+++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_sched.c
@@ -0,0 +1,109 @@
+/*
+ * Copyright 2017 Valve Corporation
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a
+ * copy of this software and associated documentation files (the "Software"),
+ * to deal in the Software without restriction, including without limitation
+ * the rights to use, copy, modify, merge, publish, distribute, sublicense,
+ * and/or sell copies of the Software, and to permit persons to whom the
+ * Software is furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.  IN NO EVENT SHALL
+ * THE COPYRIGHT HOLDER(S) OR AUTHOR(S) BE LIABLE FOR ANY CLAIM, DAMAGES OR
+ * OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE,
+ * ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
+ * OTHER DEALINGS IN THE SOFTWARE.
+ *
+ * Authors: Andres Rodriguez <andresx7@gmail.com>
+ */
+
+#include <linux/fdtable.h>
+#include <linux/pid.h>
+#include <drm/amdgpu_drm.h>
+#include "amdgpu.h"
+
+#include "amdgpu_vm.h"
+
+enum amd_sched_priority amdgpu_to_sched_priority(int amdgpu_priority)
+{
+	switch (amdgpu_priority) {
+	case AMDGPU_CTX_PRIORITY_HIGH_HW:
+		return AMD_SCHED_PRIORITY_HIGH_HW;
+	case AMDGPU_CTX_PRIORITY_HIGH_SW:
+		return AMD_SCHED_PRIORITY_HIGH_SW;
+	case AMDGPU_CTX_PRIORITY_NORMAL:
+		return AMD_SCHED_PRIORITY_NORMAL;
+	case AMDGPU_CTX_PRIORITY_LOW_SW:
+	case AMDGPU_CTX_PRIORITY_LOW_HW:
+		return AMD_SCHED_PRIORITY_LOW;
+	case AMDGPU_CTX_PRIORITY_UNSET:
+		return AMD_SCHED_PRIORITY_UNSET;
+	default:
+		WARN(1, "Invalid context priority %d\n", amdgpu_priority);
+		return AMD_SCHED_PRIORITY_INVALID;
+	}
+}
+
+static int amdgpu_sched_process_priority_override(struct amdgpu_device *adev,
+						  int fd,
+						  enum amd_sched_priority priority)
+{
+	struct file *filp = fcheck(fd);
+	struct drm_file *file;
+	struct pid *pid;
+	struct amdgpu_fpriv *fpriv;
+	struct amdgpu_ctx *ctx;
+	uint32_t id;
+
+	if (!filp)
+		return -EINVAL;
+
+	pid = get_pid(((struct drm_file *)filp->private_data)->pid);
+
+	mutex_lock(&adev->ddev->filelist_mutex);
+	list_for_each_entry(file, &adev->ddev->filelist, lhead) {
+		if (file->pid != pid)
+			continue;
+
+		fpriv = file->driver_priv;
+		idr_for_each_entry(&fpriv->ctx_mgr.ctx_handles, ctx, id)
+				amdgpu_ctx_priority_override(ctx, priority);
+	}
+	mutex_unlock(&adev->ddev->filelist_mutex);
+
+	put_pid(pid);
+
+	return 0;
+}
+
+int amdgpu_sched_ioctl(struct drm_device *dev, void *data,
+		       struct drm_file *filp)
+{
+	union drm_amdgpu_sched *args = data;
+	struct amdgpu_device *adev = dev->dev_private;
+	enum amd_sched_priority priority;
+	int r;
+
+	priority = amdgpu_to_sched_priority(args->in.priority);
+	if (args->in.flags || priority == AMD_SCHED_PRIORITY_INVALID)
+		return -EINVAL;
+
+	switch (args->in.op) {
+	case AMDGPU_SCHED_OP_PROCESS_PRIORITY_OVERRIDE:
+		r = amdgpu_sched_process_priority_override(adev,
+							   args->in.fd,
+							   priority);
+		break;
+	default:
+		DRM_ERROR("Invalid sched op specified: %d\n", args->in.op);
+		r = -EINVAL;
+		break;
+	}
+
+	return r;
+}