drm/xe: Allow to disable engines

Sometimes it's useful to load the driver with a smaller set of engines
to allow more targeted debugging, particularly on early enabling.

Besides checking what is fused off in hardware, add similar logic to
disable engines in software. This will use configfs to allow users
to set what engine to disable, so already add prepare for that. The
exact configfs interface will be added later.

Reviewed-by: Matt Roper <matthew.d.roper@intel.com>
Link: https://lore.kernel.org/r/20250528-engine-mask-v4-3-f4636d2a890a@intel.com
Signed-off-by: Lucas De Marchi <lucas.demarchi@intel.com>

3 files changed, 38 insertions, 0 deletions

diff --git a/drivers/gpu/drm/xe/xe_configfs.c b/drivers/gpu/drm/xe/xe_configfs.c
index cb9f175c89a1..8320d57ef5a8 100644
--- a/drivers/gpu/drm/xe/xe_configfs.c
+++ b/drivers/gpu/drm/xe/xe_configfs.c
@@ -226,6 +226,21 @@ void xe_configfs_clear_survivability_mode(struct pci_dev *pdev)
 	config_item_put(&dev->group.cg_item);
 }
 
+/**
+ * xe_configfs_get_engines_allowed - get engine allowed mask from configfs
+ * @pdev: pci device
+ *
+ * Find the configfs group that belongs to the pci device and return
+ * the mask of engines allowed to be used.
+ *
+ * Return: engine mask with allowed engines
+ */
+u64 xe_configfs_get_engines_allowed(struct pci_dev *pdev)
+{
+	/* dummy implementation */
+	return U64_MAX;
+}
+
 int __init xe_configfs_init(void)
 {
 	struct config_group *root = &xe_configfs.su_group;
diff --git a/drivers/gpu/drm/xe/xe_configfs.h b/drivers/gpu/drm/xe/xe_configfs.h
index ef6d231b3024..fb8764008089 100644
--- a/drivers/gpu/drm/xe/xe_configfs.h
+++ b/drivers/gpu/drm/xe/xe_configfs.h
@@ -5,6 +5,7 @@
 #ifndef _XE_CONFIGFS_H_
 #define _XE_CONFIGFS_H_
 
+#include <linux/limits.h>
 #include <linux/types.h>
 
 struct pci_dev;
@@ -14,11 +15,13 @@ int xe_configfs_init(void);
 void xe_configfs_exit(void);
 bool xe_configfs_get_survivability_mode(struct pci_dev *pdev);
 void xe_configfs_clear_survivability_mode(struct pci_dev *pdev);
+u64 xe_configfs_get_engines_allowed(struct pci_dev *pdev);
 #else
 static inline int xe_configfs_init(void) { return 0; }
 static inline void xe_configfs_exit(void) { }
 static inline bool xe_configfs_get_survivability_mode(struct pci_dev *pdev) { return false; }
 static inline void xe_configfs_clear_survivability_mode(struct pci_dev *pdev) { }
+static inline u64 xe_configfs_get_engines_allowed(struct pci_dev *pdev) { return U64_MAX; }
 #endif
 
 #endif
diff --git a/drivers/gpu/drm/xe/xe_hw_engine.c b/drivers/gpu/drm/xe/xe_hw_engine.c
index 33681169b857..3439c8522d01 100644
--- a/drivers/gpu/drm/xe/xe_hw_engine.c
+++ b/drivers/gpu/drm/xe/xe_hw_engine.c
@@ -17,6 +17,7 @@
 #include "regs/xe_irq_regs.h"
 #include "xe_assert.h"
 #include "xe_bo.h"
+#include "xe_configfs.h"
 #include "xe_device.h"
 #include "xe_execlist.h"
 #include "xe_force_wake.h"
@@ -805,6 +806,24 @@ static void check_gsc_availability(struct xe_gt *gt)
 	}
 }
 
+static void check_sw_disable(struct xe_gt *gt)
+{
+	struct xe_device *xe = gt_to_xe(gt);
+	u64 sw_allowed = xe_configfs_get_engines_allowed(to_pci_dev(xe->drm.dev));
+	enum xe_hw_engine_id id;
+
+	for (id = 0; id < XE_NUM_HW_ENGINES; ++id) {
+		if (!(gt->info.engine_mask & BIT(id)))
+			continue;
+
+		if (!(sw_allowed & BIT(id))) {
+			gt->info.engine_mask &= ~BIT(id);
+			xe_gt_info(gt, "%s disabled via configfs\n",
+				   engine_infos[id].name);
+		}
+	}
+}
+
 int xe_hw_engines_init_early(struct xe_gt *gt)
 {
 	int i;
@@ -813,6 +832,7 @@ int xe_hw_engines_init_early(struct xe_gt *gt)
 	read_copy_fuses(gt);
 	read_compute_fuses(gt);
 	check_gsc_availability(gt);
+	check_sw_disable(gt);
 
 	BUILD_BUG_ON(XE_HW_ENGINE_PREEMPT_TIMEOUT < XE_HW_ENGINE_PREEMPT_TIMEOUT_MIN);
 	BUILD_BUG_ON(XE_HW_ENGINE_PREEMPT_TIMEOUT > XE_HW_ENGINE_PREEMPT_TIMEOUT_MAX);