drm/xe/pf: Scheduler groups are incompatible with multi-lrc

Since engines in the same class can be divided across multiple groups,
the GuC does not allow scheduler groups to be active if there are
multi-lrc contexts. This means that:

1) if a MLRC context is registered when we enable scheduler groups, the
   GuC will silently ignore the configuration
2) if a MLRC context is registered after scheduler groups are enabled,
   the GuC will disable the groups and generate an adverse event.

The expectation is that the admin will ensure that all apps that use
MLRC on PF have been terminated before scheduler groups are created. A
check is added anyway to make sure we don't still have contexts waiting
to be cleaned up laying around. A check is also added at queue creation
time to block MLRC queue creation if scheduler groups have been enabled.

Signed-off-by: Daniele Ceraolo Spurio <daniele.ceraolospurio@intel.com>
Cc: Michal Wajdeczko <michal.wajdeczko@intel.com>
Reviewed-by: Michal Wajdeczko <michal.wajdeczko@intel.com>
Link: https://patch.msgid.link/20251218223846.1146344-19-daniele.ceraolospurio@intel.com

1 files changed, 21 insertions, 0 deletions

diff --git a/drivers/gpu/drm/xe/xe_guc_submit.c b/drivers/gpu/drm/xe/xe_guc_submit.c
index 1646535b86a3..7a4218f76024 100644
--- a/drivers/gpu/drm/xe/xe_guc_submit.c
+++ b/drivers/gpu/drm/xe/xe_guc_submit.c
@@ -3564,6 +3564,27 @@ void xe_guc_submit_print(struct xe_guc *guc, struct drm_printer *p)
 }
 
 /**
+ * xe_guc_has_registered_mlrc_queues - check whether there are any MLRC queues
+ * registered with the GuC
+ * @guc: GuC.
+ *
+ * Return: true if any MLRC queue is registered with the GuC, false otherwise.
+ */
+bool xe_guc_has_registered_mlrc_queues(struct xe_guc *guc)
+{
+	struct xe_exec_queue *q;
+	unsigned long index;
+
+	guard(mutex)(&guc->submission_state.lock);
+
+	xa_for_each(&guc->submission_state.exec_queue_lookup, index, q)
+		if (q->width > 1)
+			return true;
+
+	return false;
+}
+
+/**
  * xe_guc_contexts_hwsp_rebase - Re-compute GGTT references within all
  * exec queues registered to given GuC.
  * @guc: the &xe_guc struct instance