[Intel-gfx] [PATCH] drm/i915/execlists: Force single submission for sentinels

[Chris Wilson]

Currently, we only combine a sentinel request with a max-priority
barrier such that a sentinel request is always in ELSP[0] with nothing
following it. However, we will want to create similar ELSP[] submissions
providing a full-barrier in the submission queue, but without forcing
maximum priority. As such I915_FENCE_FLAG_SENTINEL takes on the
single-submission property and so we can remove the gvt special casing.

Signed-off-by: Chris Wilson <chris at chris-wilson.co.uk>
---
 drivers/gpu/drm/i915/gt/intel_context.h       | 24 +++++++-------
 drivers/gpu/drm/i915/gt/intel_context_types.h |  4 +--
 drivers/gpu/drm/i915/gt/intel_lrc.c           | 33 +++++--------------
 drivers/gpu/drm/i915/gvt/scheduler.c          |  7 ++--
 4 files changed, 26 insertions(+), 42 deletions(-)

diff --git a/drivers/gpu/drm/i915/gt/intel_context.h b/drivers/gpu/drm/i915/gt/intel_context.h
index 18efad255124..ee5d47165c12 100644
--- a/drivers/gpu/drm/i915/gt/intel_context.h
+++ b/drivers/gpu/drm/i915/gt/intel_context.h
@@ -198,18 +198,6 @@ static inline bool intel_context_set_banned(struct intel_context *ce)
 	return test_and_set_bit(CONTEXT_BANNED, &ce->flags);
 }
 
-static inline bool
-intel_context_force_single_submission(const struct intel_context *ce)
-{
-	return test_bit(CONTEXT_FORCE_SINGLE_SUBMISSION, &ce->flags);
-}
-
-static inline void
-intel_context_set_single_submission(struct intel_context *ce)
-{
-	__set_bit(CONTEXT_FORCE_SINGLE_SUBMISSION, &ce->flags);
-}
-
 static inline bool
 intel_context_nopreempt(const struct intel_context *ce)
 {
@@ -228,6 +216,18 @@ intel_context_clear_nopreempt(struct intel_context *ce)
 	clear_bit(CONTEXT_NOPREEMPT, &ce->flags);
 }
 
+static inline bool
+intel_context_is_gvt(const struct intel_context *ce)
+{
+	return test_bit(CONTEXT_GVT, &ce->flags);
+}
+
+static inline void
+intel_context_set_gvt(struct intel_context *ce)
+{
+	set_bit(CONTEXT_GVT, &ce->flags);
+}
+
 static inline u64 intel_context_get_total_runtime_ns(struct intel_context *ce)
 {
 	const u32 period =
diff --git a/drivers/gpu/drm/i915/gt/intel_context_types.h b/drivers/gpu/drm/i915/gt/intel_context_types.h
index 0f3b68b95c56..fd2703efc10c 100644
--- a/drivers/gpu/drm/i915/gt/intel_context_types.h
+++ b/drivers/gpu/drm/i915/gt/intel_context_types.h
@@ -64,8 +64,8 @@ struct intel_context {
 #define CONTEXT_VALID_BIT		2
 #define CONTEXT_USE_SEMAPHORES		3
 #define CONTEXT_BANNED			4
-#define CONTEXT_FORCE_SINGLE_SUBMISSION	5
-#define CONTEXT_NOPREEMPT		6
+#define CONTEXT_NOPREEMPT		5
+#define CONTEXT_GVT			6
 
 	u32 *lrc_reg_state;
 	u64 lrc_desc;
diff --git a/drivers/gpu/drm/i915/gt/intel_lrc.c b/drivers/gpu/drm/i915/gt/intel_lrc.c
index 112531b29f59..f0c4084c5b9a 100644
--- a/drivers/gpu/drm/i915/gt/intel_lrc.c
+++ b/drivers/gpu/drm/i915/gt/intel_lrc.c
@@ -1579,22 +1579,10 @@ static void execlists_submit_ports(struct intel_engine_cs *engine)
 		writel(EL_CTRL_LOAD, execlists->ctrl_reg);
 }
 
-static bool ctx_single_port_submission(const struct intel_context *ce)
-{
-	return (IS_ENABLED(CONFIG_DRM_I915_GVT) &&
-		intel_context_force_single_submission(ce));
-}
-
 static bool can_merge_ctx(const struct intel_context *prev,
 			  const struct intel_context *next)
 {
-	if (prev != next)
-		return false;
-
-	if (ctx_single_port_submission(prev))
-		return false;
-
-	return true;
+	return prev == next;
 }
 
 static unsigned long i915_request_flags(const struct i915_request *rq)
@@ -1844,6 +1832,12 @@ static inline void clear_ports(struct i915_request **ports, int count)
 	memset_p((void **)ports, NULL, count);
 }
 
+static bool has_sentinel(struct i915_request *prev, struct i915_request *next)
+{
+	return (i915_request_flags(prev) | i915_request_flags(next)) &
+		BIT(I915_FENCE_FLAG_SENTINEL);
+}
+
 static void execlists_dequeue(struct intel_engine_cs *engine)
 {
 	struct intel_engine_execlists * const execlists = &engine->execlists;
@@ -2125,18 +2119,7 @@ static void execlists_dequeue(struct intel_engine_cs *engine)
 				if (last->context == rq->context)
 					goto done;
 
-				if (i915_request_has_sentinel(last))
-					goto done;
-
-				/*
-				 * If GVT overrides us we only ever submit
-				 * port[0], leaving port[1] empty. Note that we
-				 * also have to be careful that we don't queue
-				 * the same context (even though a different
-				 * request) to the second port.
-				 */
-				if (ctx_single_port_submission(last->context) ||
-				    ctx_single_port_submission(rq->context))
+				if (has_sentinel(last, rq))
 					goto done;
 
 				merge = false;
diff --git a/drivers/gpu/drm/i915/gvt/scheduler.c b/drivers/gpu/drm/i915/gvt/scheduler.c
index 1c95bf8cbed0..4fccf4b194b0 100644
--- a/drivers/gpu/drm/i915/gvt/scheduler.c
+++ b/drivers/gpu/drm/i915/gvt/scheduler.c
@@ -204,9 +204,9 @@ static int populate_shadow_context(struct intel_vgpu_workload *workload)
 	return 0;
 }
 
-static inline bool is_gvt_request(struct i915_request *rq)
+static inline bool is_gvt_request(const struct i915_request *rq)
 {
-	return intel_context_force_single_submission(rq->context);
+	return intel_context_is_gvt(rq->context);
 }
 
 static void save_ring_hw_state(struct intel_vgpu *vgpu,
@@ -401,6 +401,7 @@ intel_gvt_workload_req_alloc(struct intel_vgpu_workload *workload)
 		return PTR_ERR(rq);
 	}
 
+	__set_bit(I915_FENCE_FLAG_SENTINEL, &rq->fence.flags);
 	workload->req = i915_request_get(rq);
 	return 0;
 }
@@ -1226,7 +1227,7 @@ int intel_vgpu_setup_submission(struct intel_vgpu *vgpu)
 
 		i915_vm_put(ce->vm);
 		ce->vm = i915_vm_get(&ppgtt->vm);
-		intel_context_set_single_submission(ce);
+		intel_context_set_gvt(ce);
 
 		/* Max ring buffer size */
 		if (!intel_uc_wants_guc_submission(&engine->gt->uc)) {
-- 
2.20.1