drm/xe: Introduce xe_ggtt_largest_hole

Introduce a new xe_ggtt_largest_hole helper that attends the SRIOV
demand and continue with the goal of limiting drm_mm access to xe_ggtt.

v2: Fix a typo (Michal)

Cc: Michal Wajdeczko <[e-mail]>
Reviewed-by: Lucas De Marchi <[e-mail]>
Link: https://patchwork.freedesktop.org/patch/msgid/[e-mail]
Signed-off-by: Rodrigo Vivi <[e-mail]>

drivers/gpu/drm/xe/xe_ggtt.c

···
 			    bo->flags & XE_BO_FLAG_GGTT_INVALIDATE);
 }
 
+/**
+ * xe_ggtt_largest_hole - Largest GGTT hole
+ * @ggtt: the &xe_ggtt that will be inspected
+ * @alignment: minimum alignment
+ * @spare: If not NULL: in: desired memory size to be spared / out: Adjusted possible spare
+ *
+ * Return: size of the largest continuous GGTT region
+ */
+u64 xe_ggtt_largest_hole(struct xe_ggtt *ggtt, u64 alignment, u64 *spare)
+{
+	const struct drm_mm *mm = &ggtt->mm;
+	const struct drm_mm_node *entry;
+	u64 hole_min_start = xe_wopcm_size(tile_to_xe(ggtt->tile));
+	u64 hole_start, hole_end, hole_size;
+	u64 max_hole = 0;
+
+	mutex_lock(&ggtt->lock);
+
+	drm_mm_for_each_hole(entry, mm, hole_start, hole_end) {
+		hole_start = max(hole_start, hole_min_start);
+		hole_start = ALIGN(hole_start, alignment);
+		hole_end = ALIGN_DOWN(hole_end, alignment);
+		if (hole_start >= hole_end)
+			continue;
+		hole_size = hole_end - hole_start;
+		if (spare)
+			*spare -= min3(*spare, hole_size, max_hole);
+		max_hole = max(max_hole, hole_size);
+	}
+
+	mutex_unlock(&ggtt->lock);
+
+	return max_hole;
+}
+
 #ifdef CONFIG_PCI_IOV
 static u64 xe_encode_vfid_pte(u16 vfid)
 {

drivers/gpu/drm/xe/xe_ggtt.h

···
 int xe_ggtt_insert_bo_at(struct xe_ggtt *ggtt, struct xe_bo *bo,
 			 u64 start, u64 end);
 void xe_ggtt_remove_bo(struct xe_ggtt *ggtt, struct xe_bo *bo);
+u64 xe_ggtt_largest_hole(struct xe_ggtt *ggtt, u64 alignment, u64 *spare);
 
 int xe_ggtt_dump(struct xe_ggtt *ggtt, struct drm_printer *p);
 

drivers/gpu/drm/xe/xe_gt_sriov_pf_config.c

···
 static u64 pf_get_max_ggtt(struct xe_gt *gt)
 {
 	struct xe_ggtt *ggtt = gt_to_tile(gt)->mem.ggtt;
-	const struct drm_mm *mm = &ggtt->mm;
-	const struct drm_mm_node *entry;
 	u64 alignment = pf_get_ggtt_alignment(gt);
 	u64 spare = pf_get_spare_ggtt(gt);
-	u64 hole_min_start = xe_wopcm_size(gt_to_xe(gt));
-	u64 hole_start, hole_end, hole_size;
-	u64 max_hole = 0;
+	u64 max_hole;
 
-	mutex_lock(&ggtt->lock);
-
-	drm_mm_for_each_hole(entry, mm, hole_start, hole_end) {
-		hole_start = max(hole_start, hole_min_start);
-		hole_start = ALIGN(hole_start, alignment);
-		hole_end = ALIGN_DOWN(hole_end, alignment);
-		if (hole_start >= hole_end)
-			continue;
-		hole_size = hole_end - hole_start;
-		xe_gt_sriov_dbg_verbose(gt, "HOLE start %llx size %lluK\n",
-					hole_start, hole_size / SZ_1K);
-		spare -= min3(spare, hole_size, max_hole);
-		max_hole = max(max_hole, hole_size);
-	}
-
-	mutex_unlock(&ggtt->lock);
+	max_hole = xe_ggtt_largest_hole(ggtt, alignment, &spare);
 
 	xe_gt_sriov_dbg_verbose(gt, "HOLE max %lluK reserved %lluK\n",
 				max_hole / SZ_1K, spare / SZ_1K);