drm/amdgpu: MCBP based on DRM scheduler (v9)

Trigger Mid-Command Buffer Preemption according to the priority of the software
rings and the hw fence signalling condition.

The muxer saves the locations of the indirect buffer frames from the software
ring together with the fence sequence number in its fifo queue, and pops out
those records when the fences are signalled. The locations are used to resubmit
packages in preemption scenarios by coping the chunks from the software ring.

v2: Update comment style.
v3: Fix conflict caused by previous modifications.
v4: Remove unnecessary prints.
v5: Fix corner cases for resubmission cases.
v6: Refactor functions for resubmission, calling fence_process in irq handler.
v7: Solve conflict for removing amdgpu_sw_ring.c.
v8: Add time threshold to judge if preemption request is needed.
v9: Correct comment spelling. Set fence emit timestamp before rsu assignment.

Cc: Christian Koenig <Christian.Koenig@amd.com>
Cc: Luben Tuikov <Luben.Tuikov@amd.com>
Cc: Andrey Grodzovsky <Andrey.Grodzovsky@amd.com>
Cc: Michel Dänzer <michel@daenzer.net>
Signed-off-by: Jiadong.Zhu <Jiadong.Zhu@amd.com>
Acked-by: Luben Tuikov <luben.tuikov@amd.com>
Acked-by: Huang Rui <ray.huang@amd.com>
Acked-by: Christian König <christian.koenig@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

1 files changed, 313 insertions, 38 deletions

diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_ring_mux.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_ring_mux.c
index a52c4e7e8c39..3348337379da 100644
--- a/drivers/gpu/drm/amd/amdgpu/amdgpu_ring_mux.c
+++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_ring_mux.c
@@ -28,6 +28,7 @@
 #include "amdgpu.h"
 
 #define AMDGPU_MUX_RESUBMIT_JIFFIES_TIMEOUT (HZ / 2)
+#define AMDGPU_MAX_LAST_UNSIGNALED_THRESHOLD_US 10000
 
 static const struct ring_info {
 	unsigned int hw_pio;
@@ -37,23 +38,145 @@ static const struct ring_info {
 	{ AMDGPU_RING_PRIO_2, "gfx_high"},
 };
 
+static struct kmem_cache *amdgpu_mux_chunk_slab;
+
+static inline struct amdgpu_mux_entry *amdgpu_ring_mux_sw_entry(struct amdgpu_ring_mux *mux,
+								struct amdgpu_ring *ring)
+{
+	return ring->entry_index < mux->ring_entry_size ?
+			&mux->ring_entry[ring->entry_index] : NULL;
+}
+
+/* copy packages on sw ring range[begin, end) */
+static void amdgpu_ring_mux_copy_pkt_from_sw_ring(struct amdgpu_ring_mux *mux,
+						  struct amdgpu_ring *ring,
+						  u64 s_start, u64 s_end)
+{
+	u64 start, end;
+	struct amdgpu_ring *real_ring = mux->real_ring;
+
+	start = s_start & ring->buf_mask;
+	end = s_end & ring->buf_mask;
+
+	if (start == end) {
+		DRM_ERROR("no more data copied from sw ring\n");
+		return;
+	}
+	if (start > end) {
+		amdgpu_ring_alloc(real_ring, (ring->ring_size >> 2) + end - start);
+		amdgpu_ring_write_multiple(real_ring, (void *)&ring->ring[start],
+					   (ring->ring_size >> 2) - start);
+		amdgpu_ring_write_multiple(real_ring, (void *)&ring->ring[0], end);
+	} else {
+		amdgpu_ring_alloc(real_ring, end - start);
+		amdgpu_ring_write_multiple(real_ring, (void *)&ring->ring[start], end - start);
+	}
+}
+
+static void amdgpu_mux_resubmit_chunks(struct amdgpu_ring_mux *mux)
+{
+	struct amdgpu_mux_entry *e = NULL;
+	struct amdgpu_mux_chunk *chunk;
+	uint32_t seq, last_seq;
+	int i;
+
+	/*find low priority entries:*/
+	if (!mux->s_resubmit)
+		return;
+
+	for (i = 0; i < mux->num_ring_entries; i++) {
+		if (mux->ring_entry[i].ring->hw_prio <= AMDGPU_RING_PRIO_DEFAULT) {
+			e = &mux->ring_entry[i];
+			break;
+		}
+	}
+
+	if (!e) {
+		DRM_ERROR("%s no low priority ring found\n", __func__);
+		return;
+	}
+
+	last_seq = atomic_read(&e->ring->fence_drv.last_seq);
+	seq = mux->seqno_to_resubmit;
+	if (last_seq < seq) {
+		/*resubmit all the fences between (last_seq, seq]*/
+		list_for_each_entry(chunk, &e->list, entry) {
+			if (chunk->sync_seq > last_seq && chunk->sync_seq <= seq) {
+				amdgpu_fence_update_start_timestamp(e->ring,
+								    chunk->sync_seq,
+								    ktime_get());
+				amdgpu_ring_mux_copy_pkt_from_sw_ring(mux, e->ring,
+								      chunk->start,
+								      chunk->end);
+				mux->wptr_resubmit = chunk->end;
+				amdgpu_ring_commit(mux->real_ring);
+			}
+		}
+	}
+
+	del_timer(&mux->resubmit_timer);
+	mux->s_resubmit = false;
+}
+
+static void amdgpu_ring_mux_schedule_resubmit(struct amdgpu_ring_mux *mux)
+{
+	mod_timer(&mux->resubmit_timer, jiffies + AMDGPU_MUX_RESUBMIT_JIFFIES_TIMEOUT);
+}
+
+static void amdgpu_mux_resubmit_fallback(struct timer_list *t)
+{
+	struct amdgpu_ring_mux *mux = from_timer(mux, t, resubmit_timer);
+
+	if (!spin_trylock(&mux->lock)) {
+		amdgpu_ring_mux_schedule_resubmit(mux);
+		DRM_ERROR("reschedule resubmit\n");
+		return;
+	}
+	amdgpu_mux_resubmit_chunks(mux);
+	spin_unlock(&mux->lock);
+}
+
 int amdgpu_ring_mux_init(struct amdgpu_ring_mux *mux, struct amdgpu_ring *ring,
 			 unsigned int entry_size)
 {
 	mux->real_ring = ring;
 	mux->num_ring_entries = 0;
+
 	mux->ring_entry = kcalloc(entry_size, sizeof(struct amdgpu_mux_entry), GFP_KERNEL);
 	if (!mux->ring_entry)
 		return -ENOMEM;
 
 	mux->ring_entry_size = entry_size;
+	mux->s_resubmit = false;
+
+	amdgpu_mux_chunk_slab = kmem_cache_create("amdgpu_mux_chunk",
+						  sizeof(struct amdgpu_mux_chunk), 0,
+						  SLAB_HWCACHE_ALIGN, NULL);
+	if (!amdgpu_mux_chunk_slab) {
+		DRM_ERROR("create amdgpu_mux_chunk cache failed\n");
+		return -ENOMEM;
+	}
+
 	spin_lock_init(&mux->lock);
+	timer_setup(&mux->resubmit_timer, amdgpu_mux_resubmit_fallback, 0);
 
 	return 0;
 }
 
 void amdgpu_ring_mux_fini(struct amdgpu_ring_mux *mux)
 {
+	struct amdgpu_mux_entry *e;
+	struct amdgpu_mux_chunk *chunk, *chunk2;
+	int i;
+
+	for (i = 0; i < mux->num_ring_entries; i++) {
+		e = &mux->ring_entry[i];
+		list_for_each_entry_safe(chunk, chunk2, &e->list, entry) {
+			list_del(&chunk->entry);
+			kmem_cache_free(amdgpu_mux_chunk_slab, chunk);
+		}
+	}
+	kmem_cache_destroy(amdgpu_mux_chunk_slab);
 	kfree(mux->ring_entry);
 	mux->ring_entry = NULL;
 	mux->num_ring_entries = 0;
@@ -73,62 +196,48 @@ int amdgpu_ring_mux_add_sw_ring(struct amdgpu_ring_mux *mux, struct amdgpu_ring
 	ring->entry_index = mux->num_ring_entries;
 	e->ring = ring;
 
+	INIT_LIST_HEAD(&e->list);
 	mux->num_ring_entries += 1;
 	return 0;
 }
 
-static inline struct amdgpu_mux_entry *amdgpu_ring_mux_sw_entry(struct amdgpu_ring_mux *mux,
-								struct amdgpu_ring *ring)
-{
-	return ring->entry_index < mux->ring_entry_size ?
-			&mux->ring_entry[ring->entry_index] : NULL;
-}
-
-/* copy packages on sw ring range[begin, end) */
-static void amdgpu_ring_mux_copy_pkt_from_sw_ring(struct amdgpu_ring_mux *mux,
-						  struct amdgpu_ring *ring,
-						  u64 s_start, u64 s_end)
-{
-	u64 start, end;
-	struct amdgpu_ring *real_ring = mux->real_ring;
-
-	start = s_start & ring->buf_mask;
-	end = s_end & ring->buf_mask;
-
-	if (start == end) {
-		DRM_ERROR("no more data copied from sw ring\n");
-		return;
-	}
-	if (start > end) {
-		amdgpu_ring_alloc(real_ring, (ring->ring_size >> 2) + end - start);
-		amdgpu_ring_write_multiple(real_ring, (void *)&ring->ring[start],
-					   (ring->ring_size >> 2) - start);
-		amdgpu_ring_write_multiple(real_ring, (void *)&ring->ring[0], end);
-	} else {
-		amdgpu_ring_alloc(real_ring, end - start);
-		amdgpu_ring_write_multiple(real_ring, (void *)&ring->ring[start], end - start);
-	}
-}
-
 void amdgpu_ring_mux_set_wptr(struct amdgpu_ring_mux *mux, struct amdgpu_ring *ring, u64 wptr)
 {
 	struct amdgpu_mux_entry *e;
 
+	spin_lock(&mux->lock);
+
+	if (ring->hw_prio <= AMDGPU_RING_PRIO_DEFAULT)
+		amdgpu_mux_resubmit_chunks(mux);
+
 	e = amdgpu_ring_mux_sw_entry(mux, ring);
 	if (!e) {
 		DRM_ERROR("cannot find entry for sw ring\n");
+		spin_unlock(&mux->lock);
+		return;
+	}
+
+	/* We could skip this set wptr as preemption in process. */
+	if (ring->hw_prio <= AMDGPU_RING_PRIO_DEFAULT && mux->pending_trailing_fence_signaled) {
+		spin_unlock(&mux->lock);
 		return;
 	}
 
-	spin_lock(&mux->lock);
 	e->sw_cptr = e->sw_wptr;
+	/* Update cptr if the package already copied in resubmit functions */
+	if (ring->hw_prio <= AMDGPU_RING_PRIO_DEFAULT && e->sw_cptr < mux->wptr_resubmit)
+		e->sw_cptr = mux->wptr_resubmit;
 	e->sw_wptr = wptr;
 	e->start_ptr_in_hw_ring = mux->real_ring->wptr;
 
-	amdgpu_ring_mux_copy_pkt_from_sw_ring(mux, ring, e->sw_cptr, wptr);
-	e->end_ptr_in_hw_ring = mux->real_ring->wptr;
-	amdgpu_ring_commit(mux->real_ring);
-
+	/* Skip copying for the packages already resubmitted.*/
+	if (ring->hw_prio > AMDGPU_RING_PRIO_DEFAULT || mux->wptr_resubmit < wptr) {
+		amdgpu_ring_mux_copy_pkt_from_sw_ring(mux, ring, e->sw_cptr, wptr);
+		e->end_ptr_in_hw_ring = mux->real_ring->wptr;
+		amdgpu_ring_commit(mux->real_ring);
+	} else {
+		e->end_ptr_in_hw_ring = mux->real_ring->wptr;
+	}
 	spin_unlock(&mux->lock);
 }
 
@@ -239,3 +348,169 @@ unsigned int amdgpu_sw_ring_priority(int idx)
 	return idx < ARRAY_SIZE(sw_ring_info) ?
 		sw_ring_info[idx].hw_pio : AMDGPU_RING_PRIO_DEFAULT;
 }
+
+/*Scan on low prio rings to have unsignaled fence and high ring has no fence.*/
+int amdgpu_mcbp_scan(struct amdgpu_ring_mux *mux)
+{
+	struct amdgpu_ring *ring;
+	int i, need_preempt;
+
+	need_preempt = 0;
+	for (i = 0; i < mux->num_ring_entries; i++) {
+		ring = mux->ring_entry[i].ring;
+		if (ring->hw_prio > AMDGPU_RING_PRIO_DEFAULT &&
+		    amdgpu_fence_count_emitted(ring) > 0)
+			return 0;
+		if (ring->hw_prio <= AMDGPU_RING_PRIO_DEFAULT &&
+		    amdgpu_fence_last_unsignaled_time_us(ring) >
+		    AMDGPU_MAX_LAST_UNSIGNALED_THRESHOLD_US)
+			need_preempt = 1;
+	}
+	return need_preempt && !mux->s_resubmit;
+}
+
+/* Trigger Mid-Command Buffer Preemption (MCBP) and find if we need to resubmit. */
+int amdgpu_mcbp_trigger_preempt(struct amdgpu_ring_mux *mux)
+{
+	int r;
+
+	spin_lock(&mux->lock);
+	mux->pending_trailing_fence_signaled = true;
+	r = amdgpu_ring_preempt_ib(mux->real_ring);
+	spin_unlock(&mux->lock);
+	return r;
+}
+
+void amdgpu_sw_ring_ib_begin(struct amdgpu_ring *ring)
+{
+	struct amdgpu_device *adev = ring->adev;
+	struct amdgpu_ring_mux *mux = &adev->gfx.muxer;
+
+	WARN_ON(!ring->is_sw_ring);
+	if (ring->hw_prio > AMDGPU_RING_PRIO_DEFAULT) {
+		if (amdgpu_mcbp_scan(mux) > 0)
+			amdgpu_mcbp_trigger_preempt(mux);
+		return;
+	}
+
+	amdgpu_ring_mux_start_ib(mux, ring);
+}
+
+void amdgpu_sw_ring_ib_end(struct amdgpu_ring *ring)
+{
+	struct amdgpu_device *adev = ring->adev;
+	struct amdgpu_ring_mux *mux = &adev->gfx.muxer;
+
+	WARN_ON(!ring->is_sw_ring);
+	if (ring->hw_prio > AMDGPU_RING_PRIO_DEFAULT)
+		return;
+	amdgpu_ring_mux_end_ib(mux, ring);
+}
+
+void amdgpu_ring_mux_start_ib(struct amdgpu_ring_mux *mux, struct amdgpu_ring *ring)
+{
+	struct amdgpu_mux_entry *e;
+	struct amdgpu_mux_chunk *chunk;
+
+	spin_lock(&mux->lock);
+	amdgpu_mux_resubmit_chunks(mux);
+	spin_unlock(&mux->lock);
+
+	e = amdgpu_ring_mux_sw_entry(mux, ring);
+	if (!e) {
+		DRM_ERROR("cannot find entry!\n");
+		return;
+	}
+
+	chunk = kmem_cache_alloc(amdgpu_mux_chunk_slab, GFP_KERNEL);
+	if (!chunk) {
+		DRM_ERROR("alloc amdgpu_mux_chunk_slab failed\n");
+		return;
+	}
+
+	chunk->start = ring->wptr;
+	list_add_tail(&chunk->entry, &e->list);
+}
+
+static void scan_and_remove_signaled_chunk(struct amdgpu_ring_mux *mux, struct amdgpu_ring *ring)
+{
+	uint32_t last_seq, size = 0;
+	struct amdgpu_mux_entry *e;
+	struct amdgpu_mux_chunk *chunk, *tmp;
+
+	e = amdgpu_ring_mux_sw_entry(mux, ring);
+	if (!e) {
+		DRM_ERROR("cannot find entry!\n");
+		return;
+	}
+
+	last_seq = atomic_read(&ring->fence_drv.last_seq);
+
+	list_for_each_entry_safe(chunk, tmp, &e->list, entry) {
+		if (chunk->sync_seq <= last_seq) {
+			list_del(&chunk->entry);
+			kmem_cache_free(amdgpu_mux_chunk_slab, chunk);
+		} else {
+			size++;
+		}
+	}
+}
+
+void amdgpu_ring_mux_end_ib(struct amdgpu_ring_mux *mux, struct amdgpu_ring *ring)
+{
+	struct amdgpu_mux_entry *e;
+	struct amdgpu_mux_chunk *chunk;
+
+	e = amdgpu_ring_mux_sw_entry(mux, ring);
+	if (!e) {
+		DRM_ERROR("cannot find entry!\n");
+		return;
+	}
+
+	chunk = list_last_entry(&e->list, struct amdgpu_mux_chunk, entry);
+	if (!chunk) {
+		DRM_ERROR("cannot find chunk!\n");
+		return;
+	}
+
+	chunk->end = ring->wptr;
+	chunk->sync_seq = READ_ONCE(ring->fence_drv.sync_seq);
+
+	scan_and_remove_signaled_chunk(mux, ring);
+}
+
+bool amdgpu_mcbp_handle_trailing_fence_irq(struct amdgpu_ring_mux *mux)
+{
+	struct amdgpu_mux_entry *e;
+	struct amdgpu_ring *ring = NULL;
+	int i;
+
+	if (!mux->pending_trailing_fence_signaled)
+		return false;
+
+	if (mux->real_ring->trail_seq != le32_to_cpu(*mux->real_ring->trail_fence_cpu_addr))
+		return false;
+
+	for (i = 0; i < mux->num_ring_entries; i++) {
+		e = &mux->ring_entry[i];
+		if (e->ring->hw_prio <= AMDGPU_RING_PRIO_DEFAULT) {
+			ring = e->ring;
+			break;
+		}
+	}
+
+	if (!ring) {
+		DRM_ERROR("cannot find low priority ring\n");
+		return false;
+	}
+
+	amdgpu_fence_process(ring);
+	if (amdgpu_fence_count_emitted(ring) > 0) {
+		mux->s_resubmit = true;
+		mux->seqno_to_resubmit = ring->fence_drv.sync_seq;
+		amdgpu_ring_mux_schedule_resubmit(mux);
+	}
+
+	mux->pending_trailing_fence_signaled = false;
+	return true;
+}