[PATCH 17/22] drm/amdgpu: add parameter to allocate high priority contexts v6

[Andres Rodriguez]

Add a new context creation parameter to express a global context priority.

Contexts allocated with AMDGPU_CTX_PRIORITY_HIGH will receive higher
priority to schedule their work than AMDGPU_CTX_PRIORITY_NORMAL
(default) contexts.

v2: Instead of using flags, repurpose __pad
v3: Swap enum values of _NORMAL _HIGH for backwards compatibility
v4: Validate usermode priority and store it
v5: Move priority validation into amdgpu_ctx_ioctl(), headline reword
v6: add UAPI note regarding priorities requiring CAP_SYS_ADMIN

Signed-off-by: Andres Rodriguez <andresx7 at gmail.com>
---
 drivers/gpu/drm/amd/amdgpu/amdgpu.h           |  1 +
 drivers/gpu/drm/amd/amdgpu/amdgpu_ctx.c       | 38 +++++++++++++++++++++++----
 drivers/gpu/drm/amd/scheduler/gpu_scheduler.h |  1 +
 include/uapi/drm/amdgpu_drm.h                 |  8 +++++-
 4 files changed, 42 insertions(+), 6 deletions(-)

diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu.h b/drivers/gpu/drm/amd/amdgpu/amdgpu.h
index a4c16a8..f085698 100644
--- a/drivers/gpu/drm/amd/amdgpu/amdgpu.h
+++ b/drivers/gpu/drm/amd/amdgpu/amdgpu.h
@@ -671,6 +671,7 @@ struct amdgpu_ctx {
 	spinlock_t		ring_lock;
 	struct dma_fence	**fences;
 	struct amdgpu_ctx_ring	rings[AMDGPU_MAX_RINGS];
+	int			priority;
 	bool preamble_presented;
 };
 
diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_ctx.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_ctx.c
index 400c66b..8ef6370 100644
--- a/drivers/gpu/drm/amd/amdgpu/amdgpu_ctx.c
+++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_ctx.c
@@ -25,13 +25,22 @@
 #include <drm/drmP.h>
 #include "amdgpu.h"
 
-static int amdgpu_ctx_init(struct amdgpu_device *adev, struct amdgpu_ctx *ctx)
+static int amdgpu_ctx_init(struct amdgpu_device *adev,
+			   int priority,
+			   struct amdgpu_ctx *ctx)
 {
 	unsigned i, j;
 	int r;
 
+	if (priority < 0 || priority >= AMD_SCHED_MAX_PRIORITY)
+		return -EINVAL;
+
+	if (priority == AMD_SCHED_PRIORITY_HIGH && !capable(CAP_SYS_ADMIN))
+		return -EACCES;
+
 	memset(ctx, 0, sizeof(*ctx));
 	ctx->adev = adev;
+	ctx->priority = priority;
 	kref_init(&ctx->refcount);
 	spin_lock_init(&ctx->ring_lock);
 	ctx->fences = kcalloc(amdgpu_sched_jobs * AMDGPU_MAX_RINGS,
@@ -51,7 +60,7 @@ static int amdgpu_ctx_init(struct amdgpu_device *adev, struct amdgpu_ctx *ctx)
 		struct amdgpu_ring *ring = adev->rings[i];
 		struct amd_sched_rq *rq;
 
-		rq = &ring->sched.sched_rq[AMD_SCHED_PRIORITY_NORMAL];
+		rq = &ring->sched.sched_rq[priority];
 		r = amd_sched_entity_init(&ring->sched, &ctx->rings[i].entity,
 					  rq, amdgpu_sched_jobs);
 		if (r)
@@ -90,6 +99,7 @@ static void amdgpu_ctx_fini(struct amdgpu_ctx *ctx)
 
 static int amdgpu_ctx_alloc(struct amdgpu_device *adev,
 			    struct amdgpu_fpriv *fpriv,
+			    uint32_t priority,
 			    uint32_t *id)
 {
 	struct amdgpu_ctx_mgr *mgr = &fpriv->ctx_mgr;
@@ -107,8 +117,9 @@ static int amdgpu_ctx_alloc(struct amdgpu_device *adev,
 		kfree(ctx);
 		return r;
 	}
+
 	*id = (uint32_t)r;
-	r = amdgpu_ctx_init(adev, ctx);
+	r = amdgpu_ctx_init(adev, priority, ctx);
 	if (r) {
 		idr_remove(&mgr->ctx_handles, *id);
 		*id = 0;
@@ -182,11 +193,24 @@ static int amdgpu_ctx_query(struct amdgpu_device *adev,
 	return 0;
 }
 
+static enum amd_sched_priority amdgpu_to_sched_priority(int amdgpu_priority)
+{
+	switch (amdgpu_priority) {
+	case AMDGPU_CTX_PRIORITY_HIGH:
+		return AMD_SCHED_PRIORITY_HIGH;
+	case AMDGPU_CTX_PRIORITY_NORMAL:
+		return AMD_SCHED_PRIORITY_NORMAL;
+	default:
+		WARN(1, "Invalid context priority %d\n", amdgpu_priority);
+		return AMD_SCHED_PRIORITY_NORMAL;
+	}
+}
+
 int amdgpu_ctx_ioctl(struct drm_device *dev, void *data,
 		     struct drm_file *filp)
 {
 	int r;
-	uint32_t id;
+	uint32_t id, priority;
 
 	union drm_amdgpu_ctx *args = data;
 	struct amdgpu_device *adev = dev->dev_private;
@@ -194,10 +218,14 @@ int amdgpu_ctx_ioctl(struct drm_device *dev, void *data,
 
 	r = 0;
 	id = args->in.ctx_id;
+	priority = amdgpu_to_sched_priority(args->in.priority);
+
+	if (priority >= AMD_SCHED_MAX_PRIORITY)
+		return -EINVAL;
 
 	switch (args->in.op) {
 	case AMDGPU_CTX_OP_ALLOC_CTX:
-		r = amdgpu_ctx_alloc(adev, fpriv, &id);
+		r = amdgpu_ctx_alloc(adev, fpriv, priority, &id);
 		args->out.alloc.ctx_id = id;
 		break;
 	case AMDGPU_CTX_OP_FREE_CTX:
diff --git a/drivers/gpu/drm/amd/scheduler/gpu_scheduler.h b/drivers/gpu/drm/amd/scheduler/gpu_scheduler.h
index d8dc681..2e458de 100644
--- a/drivers/gpu/drm/amd/scheduler/gpu_scheduler.h
+++ b/drivers/gpu/drm/amd/scheduler/gpu_scheduler.h
@@ -108,6 +108,7 @@ struct amd_sched_backend_ops {
 
 enum amd_sched_priority {
 	AMD_SCHED_PRIORITY_KERNEL = 0,
+	AMD_SCHED_PRIORITY_HIGH,
 	AMD_SCHED_PRIORITY_NORMAL,
 	AMD_SCHED_MAX_PRIORITY
 };
diff --git a/include/uapi/drm/amdgpu_drm.h b/include/uapi/drm/amdgpu_drm.h
index 5797283..423909e 100644
--- a/include/uapi/drm/amdgpu_drm.h
+++ b/include/uapi/drm/amdgpu_drm.h
@@ -160,13 +160,19 @@ union drm_amdgpu_bo_list {
 /* unknown cause */
 #define AMDGPU_CTX_UNKNOWN_RESET	3
 
+/* Context priority level */
+#define AMDGPU_CTX_PRIORITY_NORMAL	0
+/* Selecting a priority above NORMAL requires CAP_SYS_ADMIN */
+#define AMDGPU_CTX_PRIORITY_HIGH	1
+#define AMDGPU_CTX_PRIORITY_NUM		2
+
 struct drm_amdgpu_ctx_in {
 	/** AMDGPU_CTX_OP_* */
 	__u32	op;
 	/** For future use, no flags defined so far */
 	__u32	flags;
 	__u32	ctx_id;
-	__u32	_pad;
+	__u32	priority;
 };
 
 union drm_amdgpu_ctx_out {
-- 
2.9.3