drm/xe: Allow to exclude part of GGTT from allocations

Soon we will be required to exclude some of the GGTT addresses
from the allocations, since on some platforms running the SR-IOV VF
mode, we will be able to use only selected range of the GGTT space.

Add helper functions to manage such GGTT range exclusions, and
follow the naming from the similar concept used by GVT-g.
Reviewed-by: Piotr Piórkowski <piotr.piorkowski@intel.com>
Link: https://lore.kernel.org/r/20240111182559.629-1-michal.wajdeczko@intel.comSigned-off-by: Michal Wajdeczko <michal.wajdeczko@intel.com>

drivers/gpu/drm/xe/xe_ggtt.c

@@ -11,9 +11,12 @@
 #include <drm/i915_drm.h>
 
 #include "regs/xe_gt_regs.h"
+#include "regs/xe_regs.h"
+#include "xe_assert.h"
 #include "xe_bo.h"
 #include "xe_device.h"
 #include "xe_gt.h"
+#include "xe_gt_printk.h"
 #include "xe_gt_tlb_invalidation.h"
 #include "xe_map.h"
 #include "xe_mmio.h"
@@ -312,6 +315,74 @@ void xe_ggtt_printk(struct xe_ggtt *ggtt, const char *prefix)
 	}
 }
 
+static void xe_ggtt_dump_node(struct xe_ggtt *ggtt,
+			      const struct drm_mm_node *node, const char *description)
+{
+	char buf[10];
+
+	if (IS_ENABLED(CONFIG_DRM_XE_DEBUG)) {
+		string_get_size(node->size, 1, STRING_UNITS_2, buf, sizeof(buf));
+		xe_gt_dbg(ggtt->tile->primary_gt, "GGTT %#llx-%#llx (%s) %s\n",
+			  node->start, node->start + node->size, buf, description);
+	}
+}
+
+/**
+ * xe_ggtt_balloon - prevent allocation of specified GGTT addresses
+ * @ggtt: the &xe_ggtt where we want to make reservation
+ * @start: the starting GGTT address of the reserved region
+ * @end: then end GGTT address of the reserved region
+ * @node: the &drm_mm_node to hold reserved GGTT node
+ *
+ * Use xe_ggtt_deballoon() to release a reserved GGTT node.
+ *
+ * Return: 0 on success or a negative error code on failure.
+ */
+int xe_ggtt_balloon(struct xe_ggtt *ggtt, u64 start, u64 end, struct drm_mm_node *node)
+{
+	int err;
+
+	xe_tile_assert(ggtt->tile, start < end);
+	xe_tile_assert(ggtt->tile, IS_ALIGNED(start, XE_PAGE_SIZE));
+	xe_tile_assert(ggtt->tile, IS_ALIGNED(end, XE_PAGE_SIZE));
+	xe_tile_assert(ggtt->tile, !drm_mm_node_allocated(node));
+
+	node->color = 0;
+	node->start = start;
+	node->size = end - start;
+
+	mutex_lock(&ggtt->lock);
+	err = drm_mm_reserve_node(&ggtt->mm, node);
+	mutex_unlock(&ggtt->lock);
+
+	if (xe_gt_WARN(ggtt->tile->primary_gt, err,
+		       "Failed to balloon GGTT %#llx-%#llx (%pe)\n",
+		       node->start, node->start + node->size, ERR_PTR(err)))
+		return err;
+
+	xe_ggtt_dump_node(ggtt, node, "balloon");
+	return 0;
+}
+
+/**
+ * xe_ggtt_deballoon - release a reserved GGTT region
+ * @ggtt: the &xe_ggtt where reserved node belongs
+ * @node: the &drm_mm_node with reserved GGTT region
+ *
+ * See xe_ggtt_balloon() for details.
+ */
+void xe_ggtt_deballoon(struct xe_ggtt *ggtt, struct drm_mm_node *node)
+{
+	if (!drm_mm_node_allocated(node))
+		return;
+
+	xe_ggtt_dump_node(ggtt, node, "deballoon");
+
+	mutex_lock(&ggtt->lock);
+	drm_mm_remove_node(node);
+	mutex_unlock(&ggtt->lock);
+}
+
 int xe_ggtt_insert_special_node_locked(struct xe_ggtt *ggtt, struct drm_mm_node *node,
 				       u32 size, u32 align, u32 mm_flags)
 {

drivers/gpu/drm/xe/xe_ggtt.h

@@ -16,6 +16,9 @@ int xe_ggtt_init_early(struct xe_ggtt *ggtt);
 int xe_ggtt_init(struct xe_ggtt *ggtt);
 void xe_ggtt_printk(struct xe_ggtt *ggtt, const char *prefix);
 
+int xe_ggtt_balloon(struct xe_ggtt *ggtt, u64 start, u64 size, struct drm_mm_node *node);
+void xe_ggtt_deballoon(struct xe_ggtt *ggtt, struct drm_mm_node *node);
+
 int xe_ggtt_insert_special_node(struct xe_ggtt *ggtt, struct drm_mm_node *node,
 				u32 size, u32 align);
 int xe_ggtt_insert_special_node_locked(struct xe_ggtt *ggtt,