[PATCH v4 22/25] drm/xe: Add ULLS migration job support to GuC submission

[Matthew Brost <matthew.brost@intel.com>]

Add ULLS migration job support to GuC submission backend.

Changes required:
- On migration queue, reduce max jobs to the number of ULLS semaphores
  minus one
- Directly set the hardware engine tail via a MMIO write for ULLS jobs
  except for first ULLS job
- Set ULLS sempahore for current job releasing last job except for first
  ULLS job
- Suppress submit H2G for ULLS except for first ULLS job

Signed-off-by: Matthew Brost <matthew.brost@intel.com>
Link: https://patch.msgid.link/20260228013501.106680-24-matthew.brost@intel.com
Signed-off-by: Maarten Lankhorst <dev@lankhorst.se>
---
 drivers/gpu/drm/xe/xe_guc_submit.c | 16 +++++++++++++---
 1 file changed, 13 insertions(+), 3 deletions(-)

diff --git a/drivers/gpu/drm/xe/xe_guc_submit.c b/drivers/gpu/drm/xe/xe_guc_submit.c
index dcb4b8a4f3b7..1578d80b01b8 100644
--- a/drivers/gpu/drm/xe/xe_guc_submit.c
+++ b/drivers/gpu/drm/xe/xe_guc_submit.c
@@ -1207,6 +1207,11 @@ static void submit_exec_queue(struct xe_exec_queue *q, struct xe_sched_job *job)
 	if (exec_queue_suspended(q))
 		return;
 
+	if (job->is_ulls && !job->is_ulls_first) {
+		xe_hw_engine_write_ring_tail(q->hwe, lrc->ring.tail);
+		xe_lrc_set_ulls_semaphore(lrc, xe_sched_job_lrc_seqno(job));
+	}
+
 	if (!exec_queue_enabled(q)) {
 		action[len++] = XE_GUC_ACTION_SCHED_CONTEXT_MODE_SET;
 		action[len++] = q->guc->id;
@@ -1220,13 +1225,14 @@ static void submit_exec_queue(struct xe_exec_queue *q, struct xe_sched_job *job)
 		set_exec_queue_pending_enable(q);
 		set_exec_queue_enabled(q);
 		trace_xe_exec_queue_scheduling_enable(q);
-	} else {
+	} else if (!job->is_ulls || job->is_ulls_first) {
 		action[len++] = XE_GUC_ACTION_SCHED_CONTEXT;
 		action[len++] = q->guc->id;
 		trace_xe_exec_queue_submit(q);
 	}
 
-	xe_guc_ct_send(&guc->ct, action, len, g2h_len, num_g2h);
+	if (!job->is_ulls || job->is_ulls_first || num_g2h)
+		xe_guc_ct_send(&guc->ct, action, len, g2h_len, num_g2h);
 
 	if (extra_submit) {
 		len = 0;
@@ -2088,6 +2094,7 @@ static int guc_exec_queue_init(struct xe_exec_queue *q)
 	struct xe_guc_exec_queue *ge;
 	long timeout;
 	int err, i;
+	int max_jobs = (xe_lrc_ring_size() / MAX_JOB_SIZE_BYTES);
 
 	xe_gt_assert(guc_to_gt(guc), xe_device_uc_enabled(guc_to_xe(guc)));
 
@@ -2127,8 +2134,11 @@ static int guc_exec_queue_init(struct xe_exec_queue *q)
 		submit_wq = primary->guc->sched.base.submit_wq;
 	}
 
+	if (q->vm && q->vm->flags & XE_VM_FLAG_MIGRATION)
+		max_jobs = min(max_jobs, LRC_MIGRATION_ULLS_SEMAPHORE_COUNT - 1);
+
 	err = xe_sched_init(&ge->sched, &drm_sched_ops, &xe_sched_ops,
-			    submit_wq, xe_lrc_ring_size() / MAX_JOB_SIZE_BYTES, 64,
+			    submit_wq, max_jobs, 64,
 			    timeout, guc_to_gt(guc)->ordered_wq, NULL,
 			    ge->name, gt_to_xe(q->gt)->drm.dev);
 	if (err)
-- 
2.34.1