[PATCH v2 3/4] drm/xe/vram: Add initial support for PF-mem regions

From: Piotr Piórkowski <[email protected]>

Add helpers to allocate and initialize such a region from a
caller-provided parent, offset, and size, and assign the matching TTM
placement. The helpers do not decide when the region is needed or how
large it should be. A separate TTM VRAM manager is initialized when a
caller installs the region as the tile kernel_vram.

v2:
 - Enforce page alignment on offset/size and guard against a NULL
   parent BAR mapping (Sashiko).

Assisted-by: Claude:claude-5-sonnet
Signed-off-by: Piotr Piórkowski <[email protected]>
---
 drivers/gpu/drm/xe/xe_tile.c       |  8 ++++++
 drivers/gpu/drm/xe/xe_vram.c       | 46 ++++++++++++++++++++++++++++++
 drivers/gpu/drm/xe/xe_vram.h       |  4 +++
 drivers/gpu/drm/xe/xe_vram_types.h |  2 ++
 4 files changed, 60 insertions(+)

diff --git a/drivers/gpu/drm/xe/xe_tile.c b/drivers/gpu/drm/xe/xe_tile.c
index fd0c2e4cbdd2..e196f424fda4 100644
--- a/drivers/gpu/drm/xe/xe_tile.c
+++ b/drivers/gpu/drm/xe/xe_tile.c
@@ -198,6 +198,14 @@ int xe_tile_init_noalloc(struct xe_tile *tile)
 		xe->info.mem_region_mask |= BIT(tile->mem.vram->id) << 1;
 	}
 
+	if (IS_DGFX(xe) && tile->mem.kernel_vram &&
+	    tile->mem.kernel_vram != tile->mem.vram &&
+	    !ttm_resource_manager_used(&tile->mem.kernel_vram->ttm.manager)) {
+		err = xe_ttm_vram_mgr_init(xe, tile->mem.kernel_vram);
+		if (err)
+			return err;
+	}
+
 	return xe_tile_sysfs_init(tile);
 }
 
diff --git a/drivers/gpu/drm/xe/xe_vram.c b/drivers/gpu/drm/xe/xe_vram.c
index e5f83df98826..408733c01d4b 100644
--- a/drivers/gpu/drm/xe/xe_vram.c
+++ b/drivers/gpu/drm/xe/xe_vram.c
@@ -29,6 +29,8 @@ static const char *stringify_vram_binding(enum xe_vram_binding binding)
 	switch (binding) {
 	case XE_VRAM_BINDING_TILE:
 		return "Tile";
+	case XE_VRAM_BINDING_PFMEM:
+		return "PF-mem";
 	}
 
 	return "Unknown";
@@ -258,6 +260,11 @@ static int vram_region_init(struct xe_device *xe, struct xe_vram_region *vram,
 	if (vram->mapping)
 		return 0;
 
+	if (!lmem_bar->mapping) {
+		drm_err(&xe->drm, "Failed to map LMEM BAR\n");
+		return -ENOMEM;
+	}
+
 	vram->actual_physical_size = region_size;
 	vram->io_start = lmem_bar->io_start + offset;
 	vram->io_size = min_t(u64, usable_size, remain_io_size);
@@ -276,6 +283,45 @@ static int vram_region_init(struct xe_device *xe, struct xe_vram_region *vram,
 	return 0;
 }
 
+/**
+ * xe_vram_region_alloc_pfmem - Allocate a PF-mem VRAM region
+ * @xe: the &xe_device
+ * @id: tile id the region belongs to
+ *
+ * Return: the allocated VRAM region, or NULL on failure.
+ */
+struct xe_vram_region *xe_vram_region_alloc_pfmem(struct xe_device *xe, u8 id)
+{
+	return vram_region_alloc(xe, XE_VRAM_BINDING_PFMEM, id, XE_PL_VRAM0_PFMEM + id);
+}
+
+/**
+ * xe_vram_region_init_pfmem - Initialize a PF-mem VRAM region
+ * @vram: pre-allocated VRAM region to initialize
+ * @parent: tile VRAM region that provides the address space context
+ * @offset: region offset relative to the parent
+ * @size: region size
+ *
+ * Return: 0 on success, negative error code on failure.
+ */
+int xe_vram_region_init_pfmem(struct xe_vram_region *vram,
+			      struct xe_vram_region *parent,
+			      u64 offset, u64 size)
+{
+	struct xe_device *xe = parent->xe;
+	resource_size_t remain_io_size;
+
+	if (!size || !PAGE_ALIGNED(offset) || !PAGE_ALIGNED(size) ||
+	    offset > parent->usable_size || size > parent->usable_size - offset)
+		return -EINVAL;
+
+	remain_io_size = offset < parent->io_size ? parent->io_size - offset : 0;
+	if (!remain_io_size)
+		return -EINVAL;
+
+	return vram_region_init(xe, vram, parent, offset, size, size, remain_io_size);
+}
+
 /**
  * xe_map_resource_to_region - Map ttm resource to vram memory region
  * @res: The ttm resource
diff --git a/drivers/gpu/drm/xe/xe_vram.h b/drivers/gpu/drm/xe/xe_vram.h
index 87088ffbfd5e..021f044e496b 100644
--- a/drivers/gpu/drm/xe/xe_vram.h
+++ b/drivers/gpu/drm/xe/xe_vram.h
@@ -17,6 +17,10 @@ struct xe_vram_region *xe_map_resource_to_region(struct ttm_resource *res);
 int xe_vram_probe(struct xe_device *xe);
 
 struct xe_vram_region *xe_vram_region_alloc_tile(struct xe_device *xe, u8 id);
+struct xe_vram_region *xe_vram_region_alloc_pfmem(struct xe_device *xe, u8 id);
+int xe_vram_region_init_pfmem(struct xe_vram_region *vram,
+			      struct xe_vram_region *parent,
+			      u64 offset, u64 size);
 resource_size_t xe_vram_region_io_start(const struct xe_vram_region *vram);
 resource_size_t xe_vram_region_io_size(const struct xe_vram_region *vram);
 resource_size_t xe_vram_region_dpa_base(const struct xe_vram_region *vram);
diff --git a/drivers/gpu/drm/xe/xe_vram_types.h b/drivers/gpu/drm/xe/xe_vram_types.h
index 51884e7a679d..01690bfbcce0 100644
--- a/drivers/gpu/drm/xe/xe_vram_types.h
+++ b/drivers/gpu/drm/xe/xe_vram_types.h
@@ -18,9 +18,11 @@ struct xe_migrate;
 /**
  * enum xe_vram_binding - VRAM binding types
  * @XE_VRAM_BINDING_TILE: general-purpose VRAM region bound to a tile
+ * @XE_VRAM_BINDING_PFMEM: VRAM region reserved solely for PF kernel allocations
  */
 enum xe_vram_binding {
 	XE_VRAM_BINDING_TILE = 0,
+	XE_VRAM_BINDING_PFMEM,
 };
 
 /**
-- 
2.34.1