[Intel-gfx] [PATCH 15/25 v2] drm/i915/context: switch contexts with execbuf2

[Ben Widawsky]

Use the rsvd1 field in execbuf2 to specify the context ID associated
with the workload. This will allow the driver to do the proper context
switch when/if needed.

v2: Add checks for context switches on rings not supporting contexts.
Before the code would silently ignore such requests.

Signed-off-by: Ben Widawsky <ben at bwidawsk.net>
---
 drivers/gpu/drm/i915/i915_gem_execbuffer.c |   16 ++++++++++++++++
 include/drm/i915_drm.h                     |    8 +++++++-
 2 files changed, 23 insertions(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/i915/i915_gem_execbuffer.c b/drivers/gpu/drm/i915/i915_gem_execbuffer.c
index 974a9f1..f32d024 100644
--- a/drivers/gpu/drm/i915/i915_gem_execbuffer.c
+++ b/drivers/gpu/drm/i915/i915_gem_execbuffer.c
@@ -1044,6 +1044,7 @@ i915_gem_do_execbuffer(struct drm_device *dev, void *data,
 	struct drm_i915_gem_object *batch_obj;
 	struct drm_clip_rect *cliprects = NULL;
 	struct intel_ring_buffer *ring;
+	u32 ctx_id = i915_execbuffer2_get_context_id(*args);
 	u32 exec_start, exec_len;
 	u32 seqno;
 	u32 mask;
@@ -1065,9 +1066,19 @@ i915_gem_do_execbuffer(struct drm_device *dev, void *data,
 		break;
 	case I915_EXEC_BSD:
 		ring = &dev_priv->ring[VCS];
+		if (ctx_id != 0) {
+			DRM_DEBUG("Ring %s doesn't support contexts\n",
+				  ring->name);
+			return -EPERM;
+		}
 		break;
 	case I915_EXEC_BLT:
 		ring = &dev_priv->ring[BCS];
+		if (ctx_id != 0) {
+			DRM_DEBUG("Ring %s doesn't support contexts\n",
+				  ring->name);
+			return -EPERM;
+		}
 		break;
 	default:
 		DRM_DEBUG("execbuf with unknown ring: %d\n",
@@ -1261,6 +1272,10 @@ i915_gem_do_execbuffer(struct drm_device *dev, void *data,
 			goto err;
 	}
 
+	ret = i915_switch_context(ring, file, ctx_id);
+	if (ret)
+		goto err;
+
 	trace_i915_gem_ring_dispatch(ring, seqno);
 
 	exec_start = batch_obj->gtt_offset + args->batch_start_offset;
@@ -1367,6 +1382,7 @@ i915_gem_execbuffer(struct drm_device *dev, void *data,
 	exec2.num_cliprects = args->num_cliprects;
 	exec2.cliprects_ptr = args->cliprects_ptr;
 	exec2.flags = I915_EXEC_RENDER;
+	i915_execbuffer2_set_context_id(exec2, 0);
 
 	ret = i915_gem_do_execbuffer(dev, data, file, &exec2, exec2_list);
 	if (!ret) {
diff --git a/include/drm/i915_drm.h b/include/drm/i915_drm.h
index 6f02451..ed82b7f 100644
--- a/include/drm/i915_drm.h
+++ b/include/drm/i915_drm.h
@@ -662,13 +662,19 @@ struct drm_i915_gem_execbuffer2 {
 #define I915_EXEC_CONSTANTS_ABSOLUTE 	(1<<6)
 #define I915_EXEC_CONSTANTS_REL_SURFACE (2<<6) /* gen4/5 only */
 	__u64 flags;
-	__u64 rsvd1;
+	__u64 rsvd1; /* now used for context info */
 	__u64 rsvd2;
 };
 
 /** Resets the SO write offset registers for transform feedback on gen7. */
 #define I915_EXEC_GEN7_SOL_RESET	(1<<8)
 
+#define I915_EXEC_CONTEXT_ID_MASK	(0xffffffff)
+#define i915_execbuffer2_set_context_id(eb2, context) \
+	(eb2).rsvd1 = context & I915_EXEC_CONTEXT_ID_MASK
+#define i915_execbuffer2_get_context_id(eb2) \
+	((eb2).rsvd1 & I915_EXEC_CONTEXT_ID_MASK)
+
 struct drm_i915_gem_pin {
 	/** Handle of the buffer to be pinned. */
 	__u32 handle;
-- 
1.7.10.2