[PATCH] drm/i915/gt: Split intel_ring_submission

[Chris Wilson <chris@chris-wilson.co.uk>]

Split the legacy submission backend from the common ring buffer.

Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
---
 drivers/gpu/drm/i915/Makefile                 |   5 +-
 drivers/gpu/drm/i915/display/intel_overlay.c  |   1 +
 drivers/gpu/drm/i915/gem/i915_gem_context.c   |   3 +-
 .../gpu/drm/i915/gem/i915_gem_execbuffer.c    |   1 +
 .../gpu/drm/i915/gem/i915_gem_object_blt.c    |   1 +
 .../i915/gem/selftests/i915_gem_coherency.c   |   1 +
 drivers/gpu/drm/i915/gt/intel_context.c       |   1 +
 drivers/gpu/drm/i915/gt/intel_context.h       |   1 +
 drivers/gpu/drm/i915/gt/intel_engine.h        | 114 -------
 drivers/gpu/drm/i915/gt/intel_engine_cs.c     |   1 +
 drivers/gpu/drm/i915/gt/intel_engine_pm.c     |   1 +
 drivers/gpu/drm/i915/gt/intel_engine_types.h  |  27 +-
 drivers/gpu/drm/i915/gt/intel_lrc.c           |   1 +
 drivers/gpu/drm/i915/gt/intel_mocs.c          |   1 +
 drivers/gpu/drm/i915/gt/intel_renderstate.c   |   1 +
 drivers/gpu/drm/i915/gt/intel_ring.c          | 314 ++++++++++++++++++
 drivers/gpu/drm/i915/gt/intel_ring.h          | 131 ++++++++
 drivers/gpu/drm/i915/gt/intel_timeline.c      |   6 +-
 drivers/gpu/drm/i915/gt/intel_workarounds.c   |   1 +
 drivers/gpu/drm/i915/gt/mock_engine.c         |   1 +
 drivers/gpu/drm/i915/gt/selftest_timeline.c   |   1 +
 .../gpu/drm/i915/gt/uc/intel_guc_submission.c |   3 +-
 drivers/gpu/drm/i915/gvt/cmd_parser.c         |   2 +
 drivers/gpu/drm/i915/gvt/mmio_context.c       |   1 +
 drivers/gpu/drm/i915/gvt/scheduler.c          |   1 +
 drivers/gpu/drm/i915/i915_active.c            |   1 +
 drivers/gpu/drm/i915/i915_perf.c              |   1 +
 drivers/gpu/drm/i915/i915_request.c           |   1 +
 28 files changed, 477 insertions(+), 147 deletions(-)
 create mode 100644 drivers/gpu/drm/i915/gt/intel_ring.c
 create mode 100644 drivers/gpu/drm/i915/gt/intel_ring.h

diff --git a/drivers/gpu/drm/i915/Makefile b/drivers/gpu/drm/i915/Makefile
index a91e0a487a79..5021aa7fa187 100644
--- a/drivers/gpu/drm/i915/Makefile
+++ b/drivers/gpu/drm/i915/Makefile
@@ -90,11 +90,12 @@ gt-y += \
 	gt/intel_gt_requests.o \
 	gt/intel_llc.o \
 	gt/intel_lrc.o \
+	gt/intel_mocs.o \
 	gt/intel_rc6.o \
 	gt/intel_renderstate.o \
 	gt/intel_reset.o \
-	gt/intel_ringbuffer.o \
-	gt/intel_mocs.o \
+	gt/intel_ring.o \
+	gt/intel_ring_submission.o \
 	gt/intel_sseu.o \
 	gt/intel_timeline.o \
 	gt/intel_workarounds.o
diff --git a/drivers/gpu/drm/i915/display/intel_overlay.c b/drivers/gpu/drm/i915/display/intel_overlay.c
index 2360f19f9694..848ce07a8ec2 100644
--- a/drivers/gpu/drm/i915/display/intel_overlay.c
+++ b/drivers/gpu/drm/i915/display/intel_overlay.c
@@ -30,6 +30,7 @@
 #include <drm/i915_drm.h>
 
 #include "gem/i915_gem_pm.h"
+#include "gt/intel_ring.h"
 
 #include "i915_drv.h"
 #include "i915_reg.h"
diff --git a/drivers/gpu/drm/i915/gem/i915_gem_context.c b/drivers/gpu/drm/i915/gem/i915_gem_context.c
index df528e48e566..a03bee30fac1 100644
--- a/drivers/gpu/drm/i915/gem/i915_gem_context.c
+++ b/drivers/gpu/drm/i915/gem/i915_gem_context.c
@@ -69,9 +69,10 @@
 
 #include <drm/i915_drm.h>
 
-#include "gt/intel_lrc_reg.h"
 #include "gt/intel_engine_heartbeat.h"
 #include "gt/intel_engine_user.h"
+#include "gt/intel_lrc_reg.h"
+#include "gt/intel_ring.h"
 
 #include "i915_gem_context.h"
 #include "i915_globals.h"
diff --git a/drivers/gpu/drm/i915/gem/i915_gem_execbuffer.c b/drivers/gpu/drm/i915/gem/i915_gem_execbuffer.c
index 99d79f94e641..c88948e4094b 100644
--- a/drivers/gpu/drm/i915/gem/i915_gem_execbuffer.c
+++ b/drivers/gpu/drm/i915/gem/i915_gem_execbuffer.c
@@ -19,6 +19,7 @@
 #include "gt/intel_engine_pool.h"
 #include "gt/intel_gt.h"
 #include "gt/intel_gt_pm.h"
+#include "gt/intel_ring.h"
 
 #include "i915_drv.h"
 #include "i915_gem_clflush.h"
diff --git a/drivers/gpu/drm/i915/gem/i915_gem_object_blt.c b/drivers/gpu/drm/i915/gem/i915_gem_object_blt.c
index 5bd8de124d74..516e61e99212 100644
--- a/drivers/gpu/drm/i915/gem/i915_gem_object_blt.c
+++ b/drivers/gpu/drm/i915/gem/i915_gem_object_blt.c
@@ -8,6 +8,7 @@
 #include "gt/intel_engine_pm.h"
 #include "gt/intel_engine_pool.h"
 #include "gt/intel_gt.h"
+#include "gt/intel_ring.h"
 #include "i915_gem_clflush.h"
 #include "i915_gem_object_blt.h"
 
diff --git a/drivers/gpu/drm/i915/gem/selftests/i915_gem_coherency.c b/drivers/gpu/drm/i915/gem/selftests/i915_gem_coherency.c
index 549810f70aeb..0877ef4dff63 100644
--- a/drivers/gpu/drm/i915/gem/selftests/i915_gem_coherency.c
+++ b/drivers/gpu/drm/i915/gem/selftests/i915_gem_coherency.c
@@ -8,6 +8,7 @@
 
 #include "gt/intel_gt.h"
 #include "gt/intel_gt_pm.h"
+#include "gt/intel_ring.h"
 
 #include "i915_selftest.h"
 #include "selftests/i915_random.h"
diff --git a/drivers/gpu/drm/i915/gt/intel_context.c b/drivers/gpu/drm/i915/gt/intel_context.c
index 59c3083c1ec1..ee9d2bcd2c13 100644
--- a/drivers/gpu/drm/i915/gt/intel_context.c
+++ b/drivers/gpu/drm/i915/gt/intel_context.c
@@ -13,6 +13,7 @@
 #include "intel_context.h"
 #include "intel_engine.h"
 #include "intel_engine_pm.h"
+#include "intel_ring.h"
 
 static struct i915_global_context {
 	struct i915_global base;
diff --git a/drivers/gpu/drm/i915/gt/intel_context.h b/drivers/gpu/drm/i915/gt/intel_context.h
index dd742ac2fbdb..68b3d317d959 100644
--- a/drivers/gpu/drm/i915/gt/intel_context.h
+++ b/drivers/gpu/drm/i915/gt/intel_context.h
@@ -12,6 +12,7 @@
 #include "i915_active.h"
 #include "intel_context_types.h"
 #include "intel_engine_types.h"
+#include "intel_ring_types.h"
 #include "intel_timeline_types.h"
 
 void intel_context_init(struct intel_context *ce,
diff --git a/drivers/gpu/drm/i915/gt/intel_engine.h b/drivers/gpu/drm/i915/gt/intel_engine.h
index c7f93d05c8e0..d77b9f9f096c 100644
--- a/drivers/gpu/drm/i915/gt/intel_engine.h
+++ b/drivers/gpu/drm/i915/gt/intel_engine.h
@@ -19,7 +19,6 @@
 #include "intel_workarounds.h"
 
 struct drm_printer;
-
 struct intel_gt;
 
 /* Early gen2 devices have a cacheline of just 32 bytes, using 64 is overkill,
@@ -176,122 +175,9 @@ intel_write_status_page(struct intel_engine_cs *engine, int reg, u32 value)
 #define I915_HWS_CSB_WRITE_INDEX	0x1f
 #define CNL_HWS_CSB_WRITE_INDEX		0x2f
 
-struct intel_ring *
-intel_engine_create_ring(struct intel_engine_cs *engine, int size);
-int intel_ring_pin(struct intel_ring *ring);
-void intel_ring_reset(struct intel_ring *ring, u32 tail);
-unsigned int intel_ring_update_space(struct intel_ring *ring);
-void intel_ring_unpin(struct intel_ring *ring);
-void intel_ring_free(struct kref *ref);
-
-static inline struct intel_ring *intel_ring_get(struct intel_ring *ring)
-{
-	kref_get(&ring->ref);
-	return ring;
-}
-
-static inline void intel_ring_put(struct intel_ring *ring)
-{
-	kref_put(&ring->ref, intel_ring_free);
-}
-
 void intel_engine_stop(struct intel_engine_cs *engine);
 void intel_engine_cleanup(struct intel_engine_cs *engine);
 
-int __must_check intel_ring_cacheline_align(struct i915_request *rq);
-
-u32 __must_check *intel_ring_begin(struct i915_request *rq, unsigned int n);
-
-static inline void intel_ring_advance(struct i915_request *rq, u32 *cs)
-{
-	/* Dummy function.
-	 *
-	 * This serves as a placeholder in the code so that the reader
-	 * can compare against the preceding intel_ring_begin() and
-	 * check that the number of dwords emitted matches the space
-	 * reserved for the command packet (i.e. the value passed to
-	 * intel_ring_begin()).
-	 */
-	GEM_BUG_ON((rq->ring->vaddr + rq->ring->emit) != cs);
-}
-
-static inline u32 intel_ring_wrap(const struct intel_ring *ring, u32 pos)
-{
-	return pos & (ring->size - 1);
-}
-
-static inline bool
-intel_ring_offset_valid(const struct intel_ring *ring,
-			unsigned int pos)
-{
-	if (pos & -ring->size) /* must be strictly within the ring */
-		return false;
-
-	if (!IS_ALIGNED(pos, 8)) /* must be qword aligned */
-		return false;
-
-	return true;
-}
-
-static inline u32 intel_ring_offset(const struct i915_request *rq, void *addr)
-{
-	/* Don't write ring->size (equivalent to 0) as that hangs some GPUs. */
-	u32 offset = addr - rq->ring->vaddr;
-	GEM_BUG_ON(offset > rq->ring->size);
-	return intel_ring_wrap(rq->ring, offset);
-}
-
-static inline void
-assert_ring_tail_valid(const struct intel_ring *ring, unsigned int tail)
-{
-	GEM_BUG_ON(!intel_ring_offset_valid(ring, tail));
-
-	/*
-	 * "Ring Buffer Use"
-	 *	Gen2 BSpec "1. Programming Environment" / 1.4.4.6
-	 *	Gen3 BSpec "1c Memory Interface Functions" / 2.3.4.5
-	 *	Gen4+ BSpec "1c Memory Interface and Command Stream" / 5.3.4.5
-	 * "If the Ring Buffer Head Pointer and the Tail Pointer are on the
-	 * same cacheline, the Head Pointer must not be greater than the Tail
-	 * Pointer."
-	 *
-	 * We use ring->head as the last known location of the actual RING_HEAD,
-	 * it may have advanced but in the worst case it is equally the same
-	 * as ring->head and so we should never program RING_TAIL to advance
-	 * into the same cacheline as ring->head.
-	 */
-#define cacheline(a) round_down(a, CACHELINE_BYTES)
-	GEM_BUG_ON(cacheline(tail) == cacheline(ring->head) &&
-		   tail < ring->head);
-#undef cacheline
-}
-
-static inline unsigned int
-intel_ring_set_tail(struct intel_ring *ring, unsigned int tail)
-{
-	/* Whilst writes to the tail are strictly order, there is no
-	 * serialisation between readers and the writers. The tail may be
-	 * read by i915_request_retire() just as it is being updated
-	 * by execlists, as although the breadcrumb is complete, the context
-	 * switch hasn't been seen.
-	 */
-	assert_ring_tail_valid(ring, tail);
-	ring->tail = tail;
-	return tail;
-}
-
-static inline unsigned int
-__intel_ring_space(unsigned int head, unsigned int tail, unsigned int size)
-{
-	/*
-	 * "If the Ring Buffer Head Pointer and the Tail Pointer are on the
-	 * same cacheline, the Head Pointer must not be greater than the Tail
-	 * Pointer."
-	 */
-	GEM_BUG_ON(!is_power_of_2(size));
-	return (head - tail - CACHELINE_BYTES) & (size - 1);
-}
-
 int intel_engines_init_mmio(struct intel_gt *gt);
 int intel_engines_setup(struct intel_gt *gt);
 int intel_engines_init(struct intel_gt *gt);
diff --git a/drivers/gpu/drm/i915/gt/intel_engine_cs.c b/drivers/gpu/drm/i915/gt/intel_engine_cs.c
index cd4caf54c59c..2afa2ef90482 100644
--- a/drivers/gpu/drm/i915/gt/intel_engine_cs.c
+++ b/drivers/gpu/drm/i915/gt/intel_engine_cs.c
@@ -37,6 +37,7 @@
 #include "intel_context.h"
 #include "intel_lrc.h"
 #include "intel_reset.h"
+#include "intel_ring.h"
 
 /* Haswell does have the CXT_SIZE register however it does not appear to be
  * valid. Now, docs explain in dwords what is in the context object. The full
diff --git a/drivers/gpu/drm/i915/gt/intel_engine_pm.c b/drivers/gpu/drm/i915/gt/intel_engine_pm.c
index 6fbfa2162e54..3c0f490ff2c7 100644
--- a/drivers/gpu/drm/i915/gt/intel_engine_pm.c
+++ b/drivers/gpu/drm/i915/gt/intel_engine_pm.c
@@ -13,6 +13,7 @@
 #include "intel_gt.h"
 #include "intel_gt_pm.h"
 #include "intel_rc6.h"
+#include "intel_ring.h"
 
 static int __engine_unpark(struct intel_wakeref *wf)
 {
diff --git a/drivers/gpu/drm/i915/gt/intel_engine_types.h b/drivers/gpu/drm/i915/gt/intel_engine_types.h
index fbe89bfd3d4f..c5d1047a4bc5 100644
--- a/drivers/gpu/drm/i915/gt/intel_engine_types.h
+++ b/drivers/gpu/drm/i915/gt/intel_engine_types.h
@@ -59,6 +59,7 @@ struct i915_gem_context;
 struct i915_request;
 struct i915_sched_attr;
 struct intel_gt;
+struct intel_ring;
 struct intel_uncore;
 
 typedef u8 intel_engine_mask_t;
@@ -77,32 +78,6 @@ struct intel_instdone {
 	u32 row[I915_MAX_SLICES][I915_MAX_SUBSLICES];
 };
 
-struct intel_ring {
-	struct kref ref;
-	struct i915_vma *vma;
-	void *vaddr;
-
-	/*
-	 * As we have two types of rings, one global to the engine used
-	 * by ringbuffer submission and those that are exclusive to a
-	 * context used by execlists, we have to play safe and allow
-	 * atomic updates to the pin_count. However, the actual pinning
-	 * of the context is either done during initialisation for
-	 * ringbuffer submission or serialised as part of the context
-	 * pinning for execlists, and so we do not need a mutex ourselves
-	 * to serialise intel_ring_pin/intel_ring_unpin.
-	 */
-	atomic_t pin_count;
-
-	u32 head;
-	u32 tail;
-	u32 emit;
-
-	u32 space;
-	u32 size;
-	u32 effective_size;
-};
-
 /*
  * we use a single page to load ctx workarounds so all of these
  * values are referred in terms of dwords
diff --git a/drivers/gpu/drm/i915/gt/intel_lrc.c b/drivers/gpu/drm/i915/gt/intel_lrc.c
index 8d8fecc69809..9d59debfd168 100644
--- a/drivers/gpu/drm/i915/gt/intel_lrc.c
+++ b/drivers/gpu/drm/i915/gt/intel_lrc.c
@@ -145,6 +145,7 @@
 #include "intel_lrc_reg.h"
 #include "intel_mocs.h"
 #include "intel_reset.h"
+#include "intel_ring.h"
 #include "intel_workarounds.h"
 
 #define RING_EXECLIST_QFULL		(1 << 0x2)
diff --git a/drivers/gpu/drm/i915/gt/intel_mocs.c b/drivers/gpu/drm/i915/gt/intel_mocs.c
index 06dba7ff294e..6d4c665a997d 100644
--- a/drivers/gpu/drm/i915/gt/intel_mocs.c
+++ b/drivers/gpu/drm/i915/gt/intel_mocs.c
@@ -26,6 +26,7 @@
 #include "intel_gt.h"
 #include "intel_mocs.h"
 #include "intel_lrc.h"
+#include "intel_ring.h"
 
 /* structures required */
 struct drm_i915_mocs_entry {
diff --git a/drivers/gpu/drm/i915/gt/intel_renderstate.c b/drivers/gpu/drm/i915/gt/intel_renderstate.c
index 6d05f9c64178..c4edc35e7d89 100644
--- a/drivers/gpu/drm/i915/gt/intel_renderstate.c
+++ b/drivers/gpu/drm/i915/gt/intel_renderstate.c
@@ -27,6 +27,7 @@
 
 #include "i915_drv.h"
 #include "intel_renderstate.h"
+#include "intel_ring.h"
 
 struct intel_renderstate {
 	const struct intel_renderstate_rodata *rodata;
diff --git a/drivers/gpu/drm/i915/gt/intel_ring.c b/drivers/gpu/drm/i915/gt/intel_ring.c
new file mode 100644
index 000000000000..98876b55f851
--- /dev/null
+++ b/drivers/gpu/drm/i915/gt/intel_ring.c
@@ -0,0 +1,314 @@
+/*
+ * SPDX-License-Identifier: MIT
+ *
+ * Copyright © 2019 Intel Corporation
+ */
+
+#include "gem/i915_gem_object.h"
+#include "i915_drv.h"
+#include "i915_vma.h"
+#include "intel_engine.h"
+#include "intel_ring.h"
+#include "intel_timeline.h"
+
+unsigned int intel_ring_update_space(struct intel_ring *ring)
+{
+	unsigned int space;
+
+	space = __intel_ring_space(ring->head, ring->emit, ring->size);
+
+	ring->space = space;
+	return space;
+}
+
+int intel_ring_pin(struct intel_ring *ring)
+{
+	struct i915_vma *vma = ring->vma;
+	unsigned int flags;
+	void *addr;
+	int ret;
+
+	if (atomic_fetch_inc(&ring->pin_count))
+		return 0;
+
+	flags = PIN_GLOBAL;
+
+	/* Ring wraparound at offset 0 sometimes hangs. No idea why. */
+	flags |= PIN_OFFSET_BIAS | i915_ggtt_pin_bias(vma);
+
+	if (vma->obj->stolen)
+		flags |= PIN_MAPPABLE;
+	else
+		flags |= PIN_HIGH;
+
+	ret = i915_vma_pin(vma, 0, 0, flags);
+	if (unlikely(ret))
+		goto err_unpin;
+
+	if (i915_vma_is_map_and_fenceable(vma))
+		addr = (void __force *)i915_vma_pin_iomap(vma);
+	else
+		addr = i915_gem_object_pin_map(vma->obj,
+					       i915_coherent_map_type(vma->vm->i915));
+	if (IS_ERR(addr)) {
+		ret = PTR_ERR(addr);
+		goto err_ring;
+	}
+
+	i915_vma_make_unshrinkable(vma);
+
+	GEM_BUG_ON(ring->vaddr);
+	ring->vaddr = addr;
+
+	return 0;
+
+err_ring:
+	i915_vma_unpin(vma);
+err_unpin:
+	atomic_dec(&ring->pin_count);
+	return ret;
+}
+
+void intel_ring_reset(struct intel_ring *ring, u32 tail)
+{
+	tail = intel_ring_wrap(ring, tail);
+	ring->tail = tail;
+	ring->head = tail;
+	ring->emit = tail;
+	intel_ring_update_space(ring);
+}
+
+void intel_ring_unpin(struct intel_ring *ring)
+{
+	if (!atomic_dec_and_test(&ring->pin_count))
+		return;
+
+	/* Discard any unused bytes beyond that submitted to hw. */
+	intel_ring_reset(ring, ring->emit);
+
+	GEM_BUG_ON(!ring->vma);
+	i915_vma_unset_ggtt_write(ring->vma);
+	if (i915_vma_is_map_and_fenceable(ring->vma))
+		i915_vma_unpin_iomap(ring->vma);
+	else
+		i915_gem_object_unpin_map(ring->vma->obj);
+
+	GEM_BUG_ON(!ring->vaddr);
+	ring->vaddr = NULL;
+
+	i915_vma_unpin(ring->vma);
+	i915_vma_make_purgeable(ring->vma);
+}
+
+static struct i915_vma *create_ring_vma(struct i915_ggtt *ggtt, int size)
+{
+	struct i915_address_space *vm = &ggtt->vm;
+	struct drm_i915_private *i915 = vm->i915;
+	struct drm_i915_gem_object *obj;
+	struct i915_vma *vma;
+
+	obj = i915_gem_object_create_stolen(i915, size);
+	if (!obj)
+		obj = i915_gem_object_create_internal(i915, size);
+	if (IS_ERR(obj))
+		return ERR_CAST(obj);
+
+	/*
+	 * Mark ring buffers as read-only from GPU side (so no stray overwrites)
+	 * if supported by the platform's GGTT.
+	 */
+	if (vm->has_read_only)
+		i915_gem_object_set_readonly(obj);
+
+	vma = i915_vma_instance(obj, vm, NULL);
+	i915_gem_object_put(obj);
+
+	return vma;
+}
+
+struct intel_ring *
+intel_engine_create_ring(struct intel_engine_cs *engine, int size)
+{
+	struct drm_i915_private *i915 = engine->i915;
+	struct intel_ring *ring;
+	struct i915_vma *vma;
+
+	GEM_BUG_ON(!is_power_of_2(size));
+	GEM_BUG_ON(RING_CTL_SIZE(size) & ~RING_NR_PAGES);
+
+	ring = kzalloc(sizeof(*ring), GFP_KERNEL);
+	if (!ring)
+		return ERR_PTR(-ENOMEM);
+
+	kref_init(&ring->ref);
+
+	ring->size = size;
+	/* Workaround an erratum on the i830 which causes a hang if
+	 * the TAIL pointer points to within the last 2 cachelines
+	 * of the buffer.
+	 */
+	ring->effective_size = size;
+	if (IS_I830(i915) || IS_I845G(i915))
+		ring->effective_size -= 2 * CACHELINE_BYTES;
+
+	intel_ring_update_space(ring);
+
+	vma = create_ring_vma(engine->gt->ggtt, size);
+	if (IS_ERR(vma)) {
+		kfree(ring);
+		return ERR_CAST(vma);
+	}
+	ring->vma = vma;
+
+	return ring;
+}
+
+void intel_ring_free(struct kref *ref)
+{
+	struct intel_ring *ring = container_of(ref, typeof(*ring), ref);
+
+	i915_vma_put(ring->vma);
+
+	kfree(ring);
+}
+
+static noinline int
+wait_for_space(struct intel_ring *ring,
+	       struct intel_timeline *tl,
+	       unsigned int bytes)
+{
+	struct i915_request *target;
+	long timeout;
+
+	if (intel_ring_update_space(ring) >= bytes)
+		return 0;
+
+	GEM_BUG_ON(list_empty(&tl->requests));
+	list_for_each_entry(target, &tl->requests, link) {
+		if (target->ring != ring)
+			continue;
+
+		/* Would completion of this request free enough space? */
+		if (bytes <= __intel_ring_space(target->postfix,
+						ring->emit, ring->size))
+			break;
+	}
+
+	if (GEM_WARN_ON(&target->link == &tl->requests))
+		return -ENOSPC;
+
+	timeout = i915_request_wait(target,
+				    I915_WAIT_INTERRUPTIBLE,
+				    MAX_SCHEDULE_TIMEOUT);
+	if (timeout < 0)
+		return timeout;
+
+	i915_request_retire_upto(target);
+
+	intel_ring_update_space(ring);
+	GEM_BUG_ON(ring->space < bytes);
+	return 0;
+}
+
+u32 *intel_ring_begin(struct i915_request *rq, unsigned int num_dwords)
+{
+	struct intel_ring *ring = rq->ring;
+	const unsigned int remain_usable = ring->effective_size - ring->emit;
+	const unsigned int bytes = num_dwords * sizeof(u32);
+	unsigned int need_wrap = 0;
+	unsigned int total_bytes;
+	u32 *cs;
+
+	/* Packets must be qword aligned. */
+	GEM_BUG_ON(num_dwords & 1);
+
+	total_bytes = bytes + rq->reserved_space;
+	GEM_BUG_ON(total_bytes > ring->effective_size);
+
+	if (unlikely(total_bytes > remain_usable)) {
+		const int remain_actual = ring->size - ring->emit;
+
+		if (bytes > remain_usable) {
+			/*
+			 * Not enough space for the basic request. So need to
+			 * flush out the remainder and then wait for
+			 * base + reserved.
+			 */
+			total_bytes += remain_actual;
+			need_wrap = remain_actual | 1;
+		} else  {
+			/*
+			 * The base request will fit but the reserved space
+			 * falls off the end. So we don't need an immediate
+			 * wrap and only need to effectively wait for the
+			 * reserved size from the start of ringbuffer.
+			 */
+			total_bytes = rq->reserved_space + remain_actual;
+		}
+	}
+
+	if (unlikely(total_bytes > ring->space)) {
+		int ret;
+
+		/*
+		 * Space is reserved in the ringbuffer for finalising the
+		 * request, as that cannot be allowed to fail. During request
+		 * finalisation, reserved_space is set to 0 to stop the
+		 * overallocation and the assumption is that then we never need
+		 * to wait (which has the risk of failing with EINTR).
+		 *
+		 * See also i915_request_alloc() and i915_request_add().
+		 */
+		GEM_BUG_ON(!rq->reserved_space);
+
+		ret = wait_for_space(ring, rq->timeline, total_bytes);
+		if (unlikely(ret))
+			return ERR_PTR(ret);
+	}
+
+	if (unlikely(need_wrap)) {
+		need_wrap &= ~1;
+		GEM_BUG_ON(need_wrap > ring->space);
+		GEM_BUG_ON(ring->emit + need_wrap > ring->size);
+		GEM_BUG_ON(!IS_ALIGNED(need_wrap, sizeof(u64)));
+
+		/* Fill the tail with MI_NOOP */
+		memset64(ring->vaddr + ring->emit, 0, need_wrap / sizeof(u64));
+		ring->space -= need_wrap;
+		ring->emit = 0;
+	}
+
+	GEM_BUG_ON(ring->emit > ring->size - bytes);
+	GEM_BUG_ON(ring->space < bytes);
+	cs = ring->vaddr + ring->emit;
+	GEM_DEBUG_EXEC(memset32(cs, POISON_INUSE, bytes / sizeof(*cs)));
+	ring->emit += bytes;
+	ring->space -= bytes;
+
+	return cs;
+}
+
+/* Align the ring tail to a cacheline boundary */
+int intel_ring_cacheline_align(struct i915_request *rq)
+{
+	int num_dwords;
+	void *cs;
+
+	num_dwords = (rq->ring->emit & (CACHELINE_BYTES - 1)) / sizeof(u32);
+	if (num_dwords == 0)
+		return 0;
+
+	num_dwords = CACHELINE_DWORDS - num_dwords;
+	GEM_BUG_ON(num_dwords & 1);
+
+	cs = intel_ring_begin(rq, num_dwords);
+	if (IS_ERR(cs))
+		return PTR_ERR(cs);
+
+	memset64(cs, (u64)MI_NOOP << 32 | MI_NOOP, num_dwords / 2);
+	intel_ring_advance(rq, cs + num_dwords);
+
+	GEM_BUG_ON(rq->ring->emit & (CACHELINE_BYTES - 1));
+	return 0;
+}
+
diff --git a/drivers/gpu/drm/i915/gt/intel_ring.h b/drivers/gpu/drm/i915/gt/intel_ring.h
new file mode 100644
index 000000000000..ea2839d9e044
--- /dev/null
+++ b/drivers/gpu/drm/i915/gt/intel_ring.h
@@ -0,0 +1,131 @@
+/*
+ * SPDX-License-Identifier: MIT
+ *
+ * Copyright © 2019 Intel Corporation
+ */
+
+#ifndef INTEL_RING_H
+#define INTEL_RING_H
+
+#include "i915_gem.h" /* GEM_BUG_ON */
+#include "i915_request.h"
+#include "intel_ring_types.h"
+
+struct intel_engine_cs;
+
+struct intel_ring *
+intel_engine_create_ring(struct intel_engine_cs *engine, int size);
+
+u32 *intel_ring_begin(struct i915_request *rq, unsigned int num_dwords);
+int intel_ring_cacheline_align(struct i915_request *rq);
+
+unsigned int intel_ring_update_space(struct intel_ring *ring);
+
+int intel_ring_pin(struct intel_ring *ring);
+void intel_ring_unpin(struct intel_ring *ring);
+void intel_ring_reset(struct intel_ring *ring, u32 tail);
+
+void intel_ring_free(struct kref *ref);
+
+static inline struct intel_ring *intel_ring_get(struct intel_ring *ring)
+{
+	kref_get(&ring->ref);
+	return ring;
+}
+
+static inline void intel_ring_put(struct intel_ring *ring)
+{
+	kref_put(&ring->ref, intel_ring_free);
+}
+
+static inline void intel_ring_advance(struct i915_request *rq, u32 *cs)
+{
+	/* Dummy function.
+	 *
+	 * This serves as a placeholder in the code so that the reader
+	 * can compare against the preceding intel_ring_begin() and
+	 * check that the number of dwords emitted matches the space
+	 * reserved for the command packet (i.e. the value passed to
+	 * intel_ring_begin()).
+	 */
+	GEM_BUG_ON((rq->ring->vaddr + rq->ring->emit) != cs);
+}
+
+static inline u32 intel_ring_wrap(const struct intel_ring *ring, u32 pos)
+{
+	return pos & (ring->size - 1);
+}
+
+static inline bool
+intel_ring_offset_valid(const struct intel_ring *ring,
+			unsigned int pos)
+{
+	if (pos & -ring->size) /* must be strictly within the ring */
+		return false;
+
+	if (!IS_ALIGNED(pos, 8)) /* must be qword aligned */
+		return false;
+
+	return true;
+}
+
+static inline u32 intel_ring_offset(const struct i915_request *rq, void *addr)
+{
+	/* Don't write ring->size (equivalent to 0) as that hangs some GPUs. */
+	u32 offset = addr - rq->ring->vaddr;
+	GEM_BUG_ON(offset > rq->ring->size);
+	return intel_ring_wrap(rq->ring, offset);
+}
+
+static inline void
+assert_ring_tail_valid(const struct intel_ring *ring, unsigned int tail)
+{
+	GEM_BUG_ON(!intel_ring_offset_valid(ring, tail));
+
+	/*
+	 * "Ring Buffer Use"
+	 *	Gen2 BSpec "1. Programming Environment" / 1.4.4.6
+	 *	Gen3 BSpec "1c Memory Interface Functions" / 2.3.4.5
+	 *	Gen4+ BSpec "1c Memory Interface and Command Stream" / 5.3.4.5
+	 * "If the Ring Buffer Head Pointer and the Tail Pointer are on the
+	 * same cacheline, the Head Pointer must not be greater than the Tail
+	 * Pointer."
+	 *
+	 * We use ring->head as the last known location of the actual RING_HEAD,
+	 * it may have advanced but in the worst case it is equally the same
+	 * as ring->head and so we should never program RING_TAIL to advance
+	 * into the same cacheline as ring->head.
+	 */
+#define cacheline(a) round_down(a, CACHELINE_BYTES)
+	GEM_BUG_ON(cacheline(tail) == cacheline(ring->head) &&
+		   tail < ring->head);
+#undef cacheline
+}
+
+static inline unsigned int
+intel_ring_set_tail(struct intel_ring *ring, unsigned int tail)
+{
+	/* Whilst writes to the tail are strictly order, there is no
+	 * serialisation between readers and the writers. The tail may be
+	 * read by i915_request_retire() just as it is being updated
+	 * by execlists, as although the breadcrumb is complete, the context
+	 * switch hasn't been seen.
+	 */
+	assert_ring_tail_valid(ring, tail);
+	ring->tail = tail;
+	return tail;
+}
+
+static inline unsigned int
+__intel_ring_space(unsigned int head, unsigned int tail, unsigned int size)
+{
+	/*
+	 * "If the Ring Buffer Head Pointer and the Tail Pointer are on the
+	 * same cacheline, the Head Pointer must not be greater than the Tail
+	 * Pointer."
+	 */
+	GEM_BUG_ON(!is_power_of_2(size));
+	return (head - tail - CACHELINE_BYTES) & (size - 1);
+}
+
+#endif /* INTEL_RING_H */
diff --git a/drivers/gpu/drm/i915/gt/intel_timeline.c b/drivers/gpu/drm/i915/gt/intel_timeline.c
index 0f959694303c..14ad10acd548 100644
--- a/drivers/gpu/drm/i915/gt/intel_timeline.c
+++ b/drivers/gpu/drm/i915/gt/intel_timeline.c
@@ -4,13 +4,13 @@
  * Copyright © 2016-2018 Intel Corporation
  */
 
-#include "gt/intel_gt_types.h"
-
 #include "i915_drv.h"
 
 #include "i915_active.h"
 #include "i915_syncmap.h"
-#include "gt/intel_timeline.h"
+#include "intel_gt.h"
+#include "intel_ring.h"
+#include "intel_timeline.h"
 
 #define ptr_set_bit(ptr, bit) ((typeof(ptr))((unsigned long)(ptr) | BIT(bit)))
 #define ptr_test_bit(ptr, bit) ((unsigned long)(ptr) & BIT(bit))
diff --git a/drivers/gpu/drm/i915/gt/intel_workarounds.c b/drivers/gpu/drm/i915/gt/intel_workarounds.c
index af8a8183154a..7cb6dab4399d 100644
--- a/drivers/gpu/drm/i915/gt/intel_workarounds.c
+++ b/drivers/gpu/drm/i915/gt/intel_workarounds.c
@@ -7,6 +7,7 @@
 #include "i915_drv.h"
 #include "intel_context.h"
 #include "intel_gt.h"
+#include "intel_ring.h"
 #include "intel_workarounds.h"
 
 /**
diff --git a/drivers/gpu/drm/i915/gt/mock_engine.c b/drivers/gpu/drm/i915/gt/mock_engine.c
index 123db2c3f956..83f549d203a0 100644
--- a/drivers/gpu/drm/i915/gt/mock_engine.c
+++ b/drivers/gpu/drm/i915/gt/mock_engine.c
@@ -23,6 +23,7 @@
  */
 
 #include "gem/i915_gem_context.h"
+#include "gt/intel_ring.h"
 
 #include "i915_drv.h"
 #include "intel_context.h"
diff --git a/drivers/gpu/drm/i915/gt/selftest_timeline.c b/drivers/gpu/drm/i915/gt/selftest_timeline.c
index dac86f699a4c..f04a59fe5d2c 100644
--- a/drivers/gpu/drm/i915/gt/selftest_timeline.c
+++ b/drivers/gpu/drm/i915/gt/selftest_timeline.c
@@ -9,6 +9,7 @@
 #include "intel_engine_pm.h"
 #include "intel_gt.h"
 #include "intel_gt_requests.h"
+#include "intel_ring.h"
 
 #include "../selftests/i915_random.h"
 #include "../i915_selftest.h"
diff --git a/drivers/gpu/drm/i915/gt/uc/intel_guc_submission.c b/drivers/gpu/drm/i915/gt/uc/intel_guc_submission.c
index 009e54a3764f..1b1691aaed28 100644
--- a/drivers/gpu/drm/i915/gt/uc/intel_guc_submission.c
+++ b/drivers/gpu/drm/i915/gt/uc/intel_guc_submission.c
@@ -6,12 +6,13 @@
 #include <linux/circ_buf.h>
 
 #include "gem/i915_gem_context.h"
-
 #include "gt/intel_context.h"
 #include "gt/intel_engine_pm.h"
 #include "gt/intel_gt.h"
 #include "gt/intel_gt_pm.h"
 #include "gt/intel_lrc_reg.h"
+#include "gt/intel_ring.h"
+
 #include "intel_guc_submission.h"
 
 #include "i915_drv.h"
diff --git a/drivers/gpu/drm/i915/gvt/cmd_parser.c b/drivers/gpu/drm/i915/gvt/cmd_parser.c
index e753b1e706e2..6a3ac8cde95d 100644
--- a/drivers/gpu/drm/i915/gvt/cmd_parser.c
+++ b/drivers/gpu/drm/i915/gvt/cmd_parser.c
@@ -35,7 +35,9 @@
  */
 
 #include <linux/slab.h>
+
 #include "i915_drv.h"
+#include "gt/intel_ring.h"
 #include "gvt.h"
 #include "i915_pvinfo.h"
 #include "trace.h"
diff --git a/drivers/gpu/drm/i915/gvt/mmio_context.c b/drivers/gpu/drm/i915/gvt/mmio_context.c
index 4208e40445b1..aaf15916d29a 100644
--- a/drivers/gpu/drm/i915/gvt/mmio_context.c
+++ b/drivers/gpu/drm/i915/gvt/mmio_context.c
@@ -35,6 +35,7 @@
 
 #include "i915_drv.h"
 #include "gt/intel_context.h"
+#include "gt/intel_ring.h"
 #include "gvt.h"
 #include "trace.h"
 
diff --git a/drivers/gpu/drm/i915/gvt/scheduler.c b/drivers/gpu/drm/i915/gvt/scheduler.c
index a5b942ee3ceb..377811f8853f 100644
--- a/drivers/gpu/drm/i915/gvt/scheduler.c
+++ b/drivers/gpu/drm/i915/gvt/scheduler.c
@@ -38,6 +38,7 @@
 #include "gem/i915_gem_context.h"
 #include "gem/i915_gem_pm.h"
 #include "gt/intel_context.h"
+#include "gt/intel_ring.h"
 
 #include "i915_drv.h"
 #include "gvt.h"
diff --git a/drivers/gpu/drm/i915/i915_active.c b/drivers/gpu/drm/i915/i915_active.c
index 4c190a548ba7..3e3495838a93 100644
--- a/drivers/gpu/drm/i915/i915_active.c
+++ b/drivers/gpu/drm/i915/i915_active.c
@@ -8,6 +8,7 @@
 
 #include "gt/intel_engine_heartbeat.h"
 #include "gt/intel_engine_pm.h"
+#include "gt/intel_ring.h"
 
 #include "i915_drv.h"
 #include "i915_active.h"
diff --git a/drivers/gpu/drm/i915/i915_perf.c b/drivers/gpu/drm/i915/i915_perf.c
index 3130b0c7ed83..38d3de2dfaa6 100644
--- a/drivers/gpu/drm/i915/i915_perf.c
+++ b/drivers/gpu/drm/i915/i915_perf.c
@@ -200,6 +200,7 @@
 #include "gt/intel_engine_user.h"
 #include "gt/intel_gt.h"
 #include "gt/intel_lrc_reg.h"
+#include "gt/intel_ring.h"
 
 #include "i915_drv.h"
 #include "i915_perf.h"
diff --git a/drivers/gpu/drm/i915/i915_request.c b/drivers/gpu/drm/i915/i915_request.c
index 4575f368455d..932c5cf190b5 100644
--- a/drivers/gpu/drm/i915/i915_request.c
+++ b/drivers/gpu/drm/i915/i915_request.c
@@ -31,6 +31,7 @@
 
 #include "gem/i915_gem_context.h"
 #include "gt/intel_context.h"
+#include "gt/intel_ring.h"
 
 #include "i915_active.h"
 #include "i915_drv.h"
-- 
2.24.0.rc0

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