drm/i915: Stop storing the ring size in the ring pointer (v3)

Previously, we were storing the ring size in the ring pointer before it
was actually allocated.  We would then guard setting the ring size on
checking for CONTEXT_ALLOC_BIT.  This is error-prone at best and really
only saves us a few bytes on something that already burns at least 4K.
Instead, this patch adds a new ring_size field and makes everything use
that.

v2 (Daniel Vetter):
 - Replace 512 * SZ_4K with SZ_2M

v2 (Jason Ekstrand):
 - Rebase on top of page migration code

Signed-off-by: Jason Ekstrand <jason@jlekstrand.net>
Reviewed-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Link: https://patchwork.freedesktop.org/patch/msgid/20210708154835.528166-3-jason@jlekstrand.net

11 files changed, 14 insertions, 19 deletions

diff --git a/drivers/gpu/drm/i915/gem/i915_gem_context.c b/drivers/gpu/drm/i915/gem/i915_gem_context.c
index ddc3cc3f8f09..a4faf06022d5 100644
--- a/drivers/gpu/drm/i915/gem/i915_gem_context.c
+++ b/drivers/gpu/drm/i915/gem/i915_gem_context.c
@@ -211,8 +211,7 @@ static void intel_context_set_gem(struct intel_context *ce,
 	GEM_BUG_ON(rcu_access_pointer(ce->gem_context));
 	RCU_INIT_POINTER(ce->gem_context, ctx);
 
-	if (!test_bit(CONTEXT_ALLOC_BIT, &ce->flags))
-		ce->ring = __intel_context_ring_size(SZ_16K);
+	ce->ring_size = SZ_16K;
 
 	if (rcu_access_pointer(ctx->vm)) {
 		struct i915_address_space *vm;
diff --git a/drivers/gpu/drm/i915/gt/intel_context.c b/drivers/gpu/drm/i915/gt/intel_context.c
index 4033184f13b9..bd63813c8a80 100644
--- a/drivers/gpu/drm/i915/gt/intel_context.c
+++ b/drivers/gpu/drm/i915/gt/intel_context.c
@@ -371,7 +371,8 @@ intel_context_init(struct intel_context *ce, struct intel_engine_cs *engine)
 	ce->engine = engine;
 	ce->ops = engine->cops;
 	ce->sseu = engine->sseu;
-	ce->ring = __intel_context_ring_size(SZ_4K);
+	ce->ring = NULL;
+	ce->ring_size = SZ_4K;
 
 	ewma_runtime_init(&ce->runtime.avg);
 
diff --git a/drivers/gpu/drm/i915/gt/intel_context.h b/drivers/gpu/drm/i915/gt/intel_context.h
index f83a73a2b39f..b10cbe8fee99 100644
--- a/drivers/gpu/drm/i915/gt/intel_context.h
+++ b/drivers/gpu/drm/i915/gt/intel_context.h
@@ -175,11 +175,6 @@ int intel_context_prepare_remote_request(struct intel_context *ce,
 
 struct i915_request *intel_context_create_request(struct intel_context *ce);
 
-static inline struct intel_ring *__intel_context_ring_size(u64 sz)
-{
-	return u64_to_ptr(struct intel_ring, sz);
-}
-
 static inline bool intel_context_is_barrier(const struct intel_context *ce)
 {
 	return test_bit(CONTEXT_BARRIER_BIT, &ce->flags);
diff --git a/drivers/gpu/drm/i915/gt/intel_context_types.h b/drivers/gpu/drm/i915/gt/intel_context_types.h
index ed8c447a7346..90026c177105 100644
--- a/drivers/gpu/drm/i915/gt/intel_context_types.h
+++ b/drivers/gpu/drm/i915/gt/intel_context_types.h
@@ -82,6 +82,7 @@ struct intel_context {
 	spinlock_t signal_lock; /* protects signals, the list of requests */
 
 	struct i915_vma *state;
+	u32 ring_size;
 	struct intel_ring *ring;
 	struct intel_timeline *timeline;
 
diff --git a/drivers/gpu/drm/i915/gt/intel_engine_cs.c b/drivers/gpu/drm/i915/gt/intel_engine_cs.c
index 5ca3d1664335..d561573ed98c 100644
--- a/drivers/gpu/drm/i915/gt/intel_engine_cs.c
+++ b/drivers/gpu/drm/i915/gt/intel_engine_cs.c
@@ -807,7 +807,8 @@ intel_engine_create_pinned_context(struct intel_engine_cs *engine,
 
 	__set_bit(CONTEXT_BARRIER_BIT, &ce->flags);
 	ce->timeline = page_pack_bits(NULL, hwsp);
-	ce->ring = __intel_context_ring_size(ring_size);
+	ce->ring = NULL;
+	ce->ring_size = ring_size;
 
 	i915_vm_put(ce->vm);
 	ce->vm = i915_vm_get(vm);
diff --git a/drivers/gpu/drm/i915/gt/intel_lrc.c b/drivers/gpu/drm/i915/gt/intel_lrc.c
index a27bac0a4bfb..8ada1afe3d22 100644
--- a/drivers/gpu/drm/i915/gt/intel_lrc.c
+++ b/drivers/gpu/drm/i915/gt/intel_lrc.c
@@ -845,7 +845,7 @@ int lrc_alloc(struct intel_context *ce, struct intel_engine_cs *engine)
 	if (IS_ERR(vma))
 		return PTR_ERR(vma);
 
-	ring = intel_engine_create_ring(engine, (unsigned long)ce->ring);
+	ring = intel_engine_create_ring(engine, ce->ring_size);
 	if (IS_ERR(ring)) {
 		err = PTR_ERR(ring);
 		goto err_vma;
diff --git a/drivers/gpu/drm/i915/gt/intel_migrate.c b/drivers/gpu/drm/i915/gt/intel_migrate.c
index 14afa1974ea5..d0a7c934fd3b 100644
--- a/drivers/gpu/drm/i915/gt/intel_migrate.c
+++ b/drivers/gpu/drm/i915/gt/intel_migrate.c
@@ -232,7 +232,8 @@ struct intel_context *intel_migrate_create_context(struct intel_migrate *m)
 	if (IS_ERR(ce))
 		return ce;
 
-	ce->ring = __intel_context_ring_size(SZ_256K);
+	ce->ring = NULL;
+	ce->ring_size = SZ_256K;
 
 	i915_vm_put(ce->vm);
 	ce->vm = i915_vm_get(m->context->vm);
diff --git a/drivers/gpu/drm/i915/gt/selftest_execlists.c b/drivers/gpu/drm/i915/gt/selftest_execlists.c
index 08896ae027d5..d790b8b946ed 100644
--- a/drivers/gpu/drm/i915/gt/selftest_execlists.c
+++ b/drivers/gpu/drm/i915/gt/selftest_execlists.c
@@ -2810,7 +2810,7 @@ static int __live_preempt_ring(struct intel_engine_cs *engine,
 			goto err_ce;
 		}
 
-		tmp->ring = __intel_context_ring_size(ring_sz);
+		tmp->ring_size = ring_sz;
 
 		err = intel_context_pin(tmp);
 		if (err) {
diff --git a/drivers/gpu/drm/i915/gt/selftest_mocs.c b/drivers/gpu/drm/i915/gt/selftest_mocs.c
index b9bb0e6e97f7..8763bbeca0f7 100644
--- a/drivers/gpu/drm/i915/gt/selftest_mocs.c
+++ b/drivers/gpu/drm/i915/gt/selftest_mocs.c
@@ -28,7 +28,7 @@ static struct intel_context *mocs_context_create(struct intel_engine_cs *engine)
 		return ce;
 
 	/* We build large requests to read the registers from the ring */
-	ce->ring = __intel_context_ring_size(SZ_16K);
+	ce->ring_size = SZ_16K;
 
 	return ce;
 }
diff --git a/drivers/gpu/drm/i915/gt/selftest_timeline.c b/drivers/gpu/drm/i915/gt/selftest_timeline.c
index 64da0c91dec1..d0b6a3afcf44 100644
--- a/drivers/gpu/drm/i915/gt/selftest_timeline.c
+++ b/drivers/gpu/drm/i915/gt/selftest_timeline.c
@@ -874,7 +874,7 @@ static int create_watcher(struct hwsp_watcher *w,
 	if (IS_ERR(ce))
 		return PTR_ERR(ce);
 
-	ce->ring = __intel_context_ring_size(ringsz);
+	ce->ring_size = ringsz;
 	w->rq = intel_context_create_request(ce);
 	intel_context_put(ce);
 	if (IS_ERR(w->rq))
diff --git a/drivers/gpu/drm/i915/gvt/scheduler.c b/drivers/gpu/drm/i915/gvt/scheduler.c
index 734c37c5e347..b56a8e37a3cd 100644
--- a/drivers/gpu/drm/i915/gvt/scheduler.c
+++ b/drivers/gpu/drm/i915/gvt/scheduler.c
@@ -1409,11 +1409,8 @@ int intel_vgpu_setup_submission(struct intel_vgpu *vgpu)
 		intel_context_set_single_submission(ce);
 
 		/* Max ring buffer size */
-		if (!intel_uc_wants_guc_submission(&engine->gt->uc)) {
-			const unsigned int ring_size = 512 * SZ_4K;
-
-			ce->ring = __intel_context_ring_size(ring_size);
-		}
+		if (!intel_uc_wants_guc_submission(&engine->gt->uc))
+			ce->ring_size = SZ_2M;
 
 		s->shadow[i] = ce;
 	}