drm/xe/migrate: Add helper function to program identity map

Add an helper function to program identity map.

v2: Formatting nits
Signed-off-by: Akshata Jahagirdar <akshata.jahagirdar@intel.com>
Reviewed-by: Matthew Brost <matthew.brost@intel.com>
Signed-off-by: Matt Roper <matthew.d.roper@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/91dc05f05bd33076fb9a9f74f8495b48d2abff53.1721250309.git.akshata.jahagirdar@intel.com

drivers/gpu/drm/xe/xe_migrate.c

@@ -130,6 +130,51 @@ static u64 xe_migrate_vram_ofs(struct xe_device *xe, u64 addr)
 	return addr + (256ULL << xe_pt_shift(2));
 }
 
+static void xe_migrate_program_identity(struct xe_device *xe, struct xe_vm *vm, struct xe_bo *bo,
+					u64 map_ofs, u64 vram_offset, u16 pat_index, u64 pt_2m_ofs)
+{
+	u64 pos, ofs, flags;
+	u64 entry;
+	/* XXX: Unclear if this should be usable_size? */
+	u64 vram_limit =  xe->mem.vram.actual_physical_size +
+		xe->mem.vram.dpa_base;
+	u32 level = 2;
+
+	ofs = map_ofs + XE_PAGE_SIZE * level + vram_offset * 8;
+	flags = vm->pt_ops->pte_encode_addr(xe, 0, pat_index, level,
+					    true, 0);
+
+	xe_assert(xe, IS_ALIGNED(xe->mem.vram.usable_size, SZ_2M));
+
+	/*
+	 * Use 1GB pages when possible, last chunk always use 2M
+	 * pages as mixing reserved memory (stolen, WOCPM) with a single
+	 * mapping is not allowed on certain platforms.
+	 */
+	for (pos = xe->mem.vram.dpa_base; pos < vram_limit;
+	     pos += SZ_1G, ofs += 8) {
+		if (pos + SZ_1G >= vram_limit) {
+			entry = vm->pt_ops->pde_encode_bo(bo, pt_2m_ofs,
+							  pat_index);
+			xe_map_wr(xe, &bo->vmap, ofs, u64, entry);
+
+			flags = vm->pt_ops->pte_encode_addr(xe, 0,
+							    pat_index,
+							    level - 1,
+							    true, 0);
+
+			for (ofs = pt_2m_ofs; pos < vram_limit;
+			     pos += SZ_2M, ofs += 8)
+				xe_map_wr(xe, &bo->vmap, ofs, u64, pos | flags);
+			break;	/* Ensure pos == vram_limit assert correct */
+		}
+
+		xe_map_wr(xe, &bo->vmap, ofs, u64, pos | flags);
+	}
+
+	xe_assert(xe, pos == vram_limit);
+}
+
 static int xe_migrate_prepare_vm(struct xe_tile *tile, struct xe_migrate *m,
 				 struct xe_vm *vm)
 {
@@ -253,47 +298,10 @@ static int xe_migrate_prepare_vm(struct xe_tile *tile, struct xe_migrate *m,
 
 	/* Identity map the entire vram at 256GiB offset */
 	if (IS_DGFX(xe)) {
-		u64 pos, ofs, flags;
-		/* XXX: Unclear if this should be usable_size? */
-		u64 vram_limit =  xe->mem.vram.actual_physical_size +
-			xe->mem.vram.dpa_base;
-
-		level = 2;
-		ofs = map_ofs + XE_PAGE_SIZE * level + 256 * 8;
-		flags = vm->pt_ops->pte_encode_addr(xe, 0, pat_index, level,
-						    true, 0);
-
-		xe_assert(xe, IS_ALIGNED(xe->mem.vram.usable_size, SZ_2M));
-
-		/*
-		 * Use 1GB pages when possible, last chunk always use 2M
-		 * pages as mixing reserved memory (stolen, WOCPM) with a single
-		 * mapping is not allowed on certain platforms.
-		 */
-		for (pos = xe->mem.vram.dpa_base; pos < vram_limit;
-		     pos += SZ_1G, ofs += 8) {
-			if (pos + SZ_1G >= vram_limit) {
-				u64 pt31_ofs = bo->size - XE_PAGE_SIZE;
-
-				entry = vm->pt_ops->pde_encode_bo(bo, pt31_ofs,
-								  pat_index);
-				xe_map_wr(xe, &bo->vmap, ofs, u64, entry);
-
-				flags = vm->pt_ops->pte_encode_addr(xe, 0,
-								    pat_index,
-								    level - 1,
-								    true, 0);
-
-				for (ofs = pt31_ofs; pos < vram_limit;
-				     pos += SZ_2M, ofs += 8)
-					xe_map_wr(xe, &bo->vmap, ofs, u64, pos | flags);
-				break;	/* Ensure pos == vram_limit assert correct */
-			}
-
-			xe_map_wr(xe, &bo->vmap, ofs, u64, pos | flags);
-		}
+		u64 pt31_ofs = bo->size - XE_PAGE_SIZE;
 
-		xe_assert(xe, pos == vram_limit);
+		xe_migrate_program_identity(xe, vm, bo, map_ofs, 256, pat_index, pt31_ofs);
+		xe_assert(xe, (xe->mem.vram.actual_physical_size <= SZ_256G));
 	}
 
 	/*