drm/i915: Switch back to an array of logical per-engine HW contexts

We switched to a tree of per-engine HW context to accommodate the
introduction of virtual engines. However, we plan to also support
multiple instances of the same engine within the GEM context, defeating
our use of the engine as a key to looking up the HW context. Just
allocate a logical per-engine instance and always use an index into the
ctx->engines[]. Later on, this ctx->engines[] may be replaced by a user
specified map.

v2: Add for_each_gem_engine() helper to iterator within the engines lock
v3: intel_context_create_request() helper
v4: s/unsigned long/unsigned int/ 4 billion engines is quite enough.
v5: Push iterator locking to caller

Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Tvrtko Ursulin <tvrtko.ursulin@intel.com>
Reviewed-by: Tvrtko Ursulin <tvrtko.ursulin@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20190426163336.15906-7-chris@chris-wilson.co.uk

1 files changed, 46 insertions, 34 deletions

diff --git a/drivers/gpu/drm/i915/i915_perf.c b/drivers/gpu/drm/i915/i915_perf.c
index afaeabe5e531..c4995d5a16d2 100644
--- a/drivers/gpu/drm/i915/i915_perf.c
+++ b/drivers/gpu/drm/i915/i915_perf.c
@@ -1203,35 +1203,35 @@ static int i915_oa_read(struct i915_perf_stream *stream,
 static struct intel_context *oa_pin_context(struct drm_i915_private *i915,
 					    struct i915_gem_context *ctx)
 {
-	struct intel_engine_cs *engine = i915->engine[RCS0];
+	struct i915_gem_engines_iter it;
 	struct intel_context *ce;
 	int err;
 
-	ce = intel_context_instance(ctx, engine);
-	if (IS_ERR(ce))
-		return ce;
-
 	err = i915_mutex_lock_interruptible(&i915->drm);
-	if (err) {
-		intel_context_put(ce);
+	if (err)
 		return ERR_PTR(err);
+
+	for_each_gem_engine(ce, i915_gem_context_lock_engines(ctx), it) {
+		if (ce->engine->class != RENDER_CLASS)
+			continue;
+
+		/*
+		 * As the ID is the gtt offset of the context's vma we
+		 * pin the vma to ensure the ID remains fixed.
+		 */
+		err = intel_context_pin(ce);
+		if (err == 0) {
+			i915->perf.oa.pinned_ctx = ce;
+			break;
+		}
 	}
+	i915_gem_context_unlock_engines(ctx);
 
-	/*
-	 * As the ID is the gtt offset of the context's vma we
-	 * pin the vma to ensure the ID remains fixed.
-	 *
-	 * NB: implied RCS engine...
-	 */
-	err = intel_context_pin(ce);
 	mutex_unlock(&i915->drm.struct_mutex);
-	intel_context_put(ce);
 	if (err)
 		return ERR_PTR(err);
 
-	i915->perf.oa.pinned_ctx = ce;
-
-	return ce;
+	return i915->perf.oa.pinned_ctx;
 }
 
 /**
@@ -1717,7 +1717,6 @@ gen8_update_reg_state_unlocked(struct intel_context *ce,
 static int gen8_configure_all_contexts(struct drm_i915_private *dev_priv,
 				       const struct i915_oa_config *oa_config)
 {
-	struct intel_engine_cs *engine = dev_priv->engine[RCS0];
 	unsigned int map_type = i915_coherent_map_type(dev_priv);
 	struct i915_gem_context *ctx;
 	struct i915_request *rq;
@@ -1746,30 +1745,43 @@ static int gen8_configure_all_contexts(struct drm_i915_private *dev_priv,
 
 	/* Update all contexts now that we've stalled the submission. */
 	list_for_each_entry(ctx, &dev_priv->contexts.list, link) {
-		struct intel_context *ce = intel_context_lookup(ctx, engine);
-		u32 *regs;
-
-		/* OA settings will be set upon first use */
-		if (!ce || !ce->state)
-			continue;
-
-		regs = i915_gem_object_pin_map(ce->state->obj, map_type);
-		if (IS_ERR(regs))
-			return PTR_ERR(regs);
+		struct i915_gem_engines_iter it;
+		struct intel_context *ce;
+
+		for_each_gem_engine(ce,
+				    i915_gem_context_lock_engines(ctx),
+				    it) {
+			u32 *regs;
+
+			if (ce->engine->class != RENDER_CLASS)
+				continue;
+
+			/* OA settings will be set upon first use */
+			if (!ce->state)
+				continue;
+
+			regs = i915_gem_object_pin_map(ce->state->obj,
+						       map_type);
+			if (IS_ERR(regs)) {
+				i915_gem_context_unlock_engines(ctx);
+				return PTR_ERR(regs);
+			}
 
-		ce->state->obj->mm.dirty = true;
-		regs += LRC_STATE_PN * PAGE_SIZE / sizeof(*regs);
+			ce->state->obj->mm.dirty = true;
+			regs += LRC_STATE_PN * PAGE_SIZE / sizeof(*regs);
 
-		gen8_update_reg_state_unlocked(ce, regs, oa_config);
+			gen8_update_reg_state_unlocked(ce, regs, oa_config);
 
-		i915_gem_object_unpin_map(ce->state->obj);
+			i915_gem_object_unpin_map(ce->state->obj);
+		}
+		i915_gem_context_unlock_engines(ctx);
 	}
 
 	/*
 	 * Apply the configuration by doing one context restore of the edited
 	 * context image.
 	 */
-	rq = i915_request_create(engine->kernel_context);
+	rq = i915_request_create(dev_priv->engine[RCS0]->kernel_context);
 	if (IS_ERR(rq))
 		return PTR_ERR(rq);