drm/i915: Remove last traces of exec-id (GEM_BUSY)

As we allow per-context engine allows the legacy concept of
I915_EXEC_RING no longer applies universally. We are still exposing the
unrelated exec-id in GEM_BUSY, so transition this ioctl (once more
slightly changing its ABI, but no one cares) over to only reporting the
uabi-class (not instance as we can not foreseeably fit those into the
small bitmask).

The only user of the extended ring information from GEM_BUSY is ddx/sna,
which tries to use the non-rcs business information to guide which
engine to use for subsequent operations on foreign bo. All that matters
for it is the decision between rcs and !rcs, so it is unaffected by the
change in higher bits.

Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Reviewed-by: Tvrtko Ursulin <tvrtko.ursulin@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20190305162643.20243-1-chris@chris-wilson.co.uk

3 files changed, 17 insertions, 26 deletions

diff --git a/drivers/gpu/drm/i915/i915_gem.c b/drivers/gpu/drm/i915/i915_gem.c
index a1ad5e137a97..69413f99ed04 100644
--- a/drivers/gpu/drm/i915/i915_gem.c
+++ b/drivers/gpu/drm/i915/i915_gem.c
@@ -3825,20 +3825,17 @@ i915_gem_object_ggtt_pin(struct drm_i915_gem_object *obj,
 
 static __always_inline unsigned int __busy_read_flag(unsigned int id)
 {
-	/* Note that we could alias engines in the execbuf API, but
-	 * that would be very unwise as it prevents userspace from
-	 * fine control over engine selection. Ahem.
-	 *
-	 * This should be something like EXEC_MAX_ENGINE instead of
-	 * I915_NUM_ENGINES.
-	 */
-	BUILD_BUG_ON(I915_NUM_ENGINES > 16);
+	if (id == I915_ENGINE_CLASS_INVALID)
+		return 0xffff0000;
+
+	GEM_BUG_ON(id >= 16);
 	return 0x10000 << id;
 }
 
 static __always_inline unsigned int __busy_write_id(unsigned int id)
 {
-	/* The uABI guarantees an active writer is also amongst the read
+	/*
+	 * The uABI guarantees an active writer is also amongst the read
 	 * engines. This would be true if we accessed the activity tracking
 	 * under the lock, but as we perform the lookup of the object and
 	 * its activity locklessly we can not guarantee that the last_write
@@ -3846,16 +3843,20 @@ static __always_inline unsigned int __busy_write_id(unsigned int id)
 	 * last_read - hence we always set both read and write busy for
 	 * last_write.
 	 */
-	return id | __busy_read_flag(id);
+	if (id == I915_ENGINE_CLASS_INVALID)
+		return 0xffffffff;
+
+	return (id + 1) | __busy_read_flag(id);
 }
 
 static __always_inline unsigned int
 __busy_set_if_active(const struct dma_fence *fence,
 		     unsigned int (*flag)(unsigned int id))
 {
-	struct i915_request *rq;
+	const struct i915_request *rq;
 
-	/* We have to check the current hw status of the fence as the uABI
+	/*
+	 * We have to check the current hw status of the fence as the uABI
 	 * guarantees forward progress. We could rely on the idle worker
 	 * to eventually flush us, but to minimise latency just ask the
 	 * hardware.
@@ -3866,11 +3867,11 @@ __busy_set_if_active(const struct dma_fence *fence,
 		return 0;
 
 	/* opencode to_request() in order to avoid const warnings */
-	rq = container_of(fence, struct i915_request, fence);
+	rq = container_of(fence, const struct i915_request, fence);
 	if (i915_request_completed(rq))
 		return 0;
 
-	return flag(rq->engine->uabi_id);
+	return flag(rq->engine->uabi_class);
 }
 
 static __always_inline unsigned int
@@ -3904,7 +3905,8 @@ i915_gem_busy_ioctl(struct drm_device *dev, void *data,
 	if (!obj)
 		goto out;
 
-	/* A discrepancy here is that we do not report the status of
+	/*
+	 * A discrepancy here is that we do not report the status of
 	 * non-i915 fences, i.e. even though we may report the object as idle,
 	 * a call to set-domain may still stall waiting for foreign rendering.
 	 * This also means that wait-ioctl may report an object as busy,
diff --git a/drivers/gpu/drm/i915/intel_engine_cs.c b/drivers/gpu/drm/i915/intel_engine_cs.c
index 4fc7e2ac6278..f3f161c5627b 100644
--- a/drivers/gpu/drm/i915/intel_engine_cs.c
+++ b/drivers/gpu/drm/i915/intel_engine_cs.c
@@ -84,7 +84,6 @@ static const struct engine_class_info intel_engine_classes[] = {
 #define MAX_MMIO_BASES 3
 struct engine_info {
 	unsigned int hw_id;
-	unsigned int uabi_id;
 	u8 class;
 	u8 instance;
 	/* mmio bases table *must* be sorted in reverse gen order */
@@ -97,7 +96,6 @@ struct engine_info {
 static const struct engine_info intel_engines[] = {
 	[RCS] = {
 		.hw_id = RCS_HW,
-		.uabi_id = I915_EXEC_RENDER,
 		.class = RENDER_CLASS,
 		.instance = 0,
 		.mmio_bases = {
@@ -106,7 +104,6 @@ static const struct engine_info intel_engines[] = {
 	},
 	[BCS] = {
 		.hw_id = BCS_HW,
-		.uabi_id = I915_EXEC_BLT,
 		.class = COPY_ENGINE_CLASS,
 		.instance = 0,
 		.mmio_bases = {
@@ -115,7 +112,6 @@ static const struct engine_info intel_engines[] = {
 	},
 	[VCS] = {
 		.hw_id = VCS_HW,
-		.uabi_id = I915_EXEC_BSD,
 		.class = VIDEO_DECODE_CLASS,
 		.instance = 0,
 		.mmio_bases = {
@@ -126,7 +122,6 @@ static const struct engine_info intel_engines[] = {
 	},
 	[VCS2] = {
 		.hw_id = VCS2_HW,
-		.uabi_id = I915_EXEC_BSD,
 		.class = VIDEO_DECODE_CLASS,
 		.instance = 1,
 		.mmio_bases = {
@@ -136,7 +131,6 @@ static const struct engine_info intel_engines[] = {
 	},
 	[VCS3] = {
 		.hw_id = VCS3_HW,
-		.uabi_id = I915_EXEC_BSD,
 		.class = VIDEO_DECODE_CLASS,
 		.instance = 2,
 		.mmio_bases = {
@@ -145,7 +139,6 @@ static const struct engine_info intel_engines[] = {
 	},
 	[VCS4] = {
 		.hw_id = VCS4_HW,
-		.uabi_id = I915_EXEC_BSD,
 		.class = VIDEO_DECODE_CLASS,
 		.instance = 3,
 		.mmio_bases = {
@@ -154,7 +147,6 @@ static const struct engine_info intel_engines[] = {
 	},
 	[VECS] = {
 		.hw_id = VECS_HW,
-		.uabi_id = I915_EXEC_VEBOX,
 		.class = VIDEO_ENHANCEMENT_CLASS,
 		.instance = 0,
 		.mmio_bases = {
@@ -164,7 +156,6 @@ static const struct engine_info intel_engines[] = {
 	},
 	[VECS2] = {
 		.hw_id = VECS2_HW,
-		.uabi_id = I915_EXEC_VEBOX,
 		.class = VIDEO_ENHANCEMENT_CLASS,
 		.instance = 1,
 		.mmio_bases = {
@@ -321,7 +312,6 @@ intel_engine_setup(struct drm_i915_private *dev_priv,
 	engine->class = info->class;
 	engine->instance = info->instance;
 
-	engine->uabi_id = info->uabi_id;
 	engine->uabi_class = intel_engine_classes[info->class].uabi_class;
 
 	engine->context_size = __intel_engine_context_size(dev_priv,
diff --git a/drivers/gpu/drm/i915/intel_ringbuffer.h b/drivers/gpu/drm/i915/intel_ringbuffer.h
index 2e7264119ec4..12e79828dbd5 100644
--- a/drivers/gpu/drm/i915/intel_ringbuffer.h
+++ b/drivers/gpu/drm/i915/intel_ringbuffer.h
@@ -335,7 +335,6 @@ struct intel_engine_cs {
 	unsigned int hw_id;
 	unsigned int guc_id;
 
-	u8 uabi_id;
 	u8 uabi_class;
 
 	u8 class;