[PATCH i-g-t v3 1/2] lib/xe: Introduce aligned buffer mapping

[nishit.sharma@intel.com]

From: Nishit Sharma <nishit.sharma@intel.com>

Added aligned buffer mapping which is providing an interface for mapping
buffer objects with a specified alignment. This API improves
cross-platform compatibility and simplifies batch buffer setup by
eliminating the need for platform-specific address handling.

Signed-off-by: Thomas Hellstrom <thomas.hellstrom@intel.com>
Signed-off-by: Nishit Sharma <nishit.sharma@intel.com>
---
 lib/xe/xe_ioctl.c | 42 ++++++++++++++++++++++++++++++++++++++++++
 lib/xe/xe_ioctl.h |  1 +
 2 files changed, 43 insertions(+)

diff --git a/lib/xe/xe_ioctl.c b/lib/xe/xe_ioctl.c
index 16aae05c9..566a08a8f 100644
--- a/lib/xe/xe_ioctl.c
+++ b/lib/xe/xe_ioctl.c
@@ -579,6 +579,48 @@ void *xe_bo_map_fixed(int fd, uint32_t bo, size_t size, uint64_t addr)
 	return map;
 }
 
+/**
+ * xe_bo_map_aligned: Maps a buffer object (bo) into
+ * CPU address space with a specified alignment
+ * @fd: The device file-descriptor
+ * @bo: The buffer object
+ * @size: The size of the map
+ * @alignment: The requested map alignment
+ *
+ * Return: pointer to CPU-Mapped BO with requested alignment
+ */
+void *xe_bo_map_aligned(int fd, uint32_t bo, size_t size, size_t alignment)
+{
+	size_t anon_size = size + alignment;
+	uint64_t anon_addr;
+	void *anon_map, *map;
+	uint64_t map_addr;
+	size_t hole_size;
+
+	/* Reserve a range of virtual space where we can fit an aligned map */
+	anon_map = mmap(NULL, anon_size, PROT_NONE, MAP_PRIVATE | MAP_ANONYMOUS, -1, 0);
+	igt_assert(anon_map != MAP_FAILED);
+	anon_addr = to_user_pointer(anon_map);
+
+	/* Compute the first aligned address within the virtual space. */
+	map_addr = ALIGN(anon_addr, alignment);
+	/* Map the bo there, replacing part of the reserved virtual range. */
+	map = xe_bo_map_fixed(fd, bo, size, map_addr);
+	igt_assert(((uintptr_t)map % alignment) == 0);
+
+	/* Unreserve part of the virtual range (if any) *before* the bo map */
+	hole_size = map_addr - anon_addr;
+	if (hole_size)
+		igt_assert(munmap(anon_map, hole_size) == 0);
+
+	/* Unreserve part of the virtual range (if any) *after* the bo map */
+	hole_size = anon_size - hole_size - size;
+	if (hole_size)
+		igt_assert(munmap(map + size, hole_size) == 0);
+
+	return map;
+}
+
 void *xe_bo_mmap_ext(int fd, uint32_t bo, size_t size, int prot)
 {
 	return __xe_bo_map(fd, bo, size, prot);
diff --git a/lib/xe/xe_ioctl.h b/lib/xe/xe_ioctl.h
index 3ea651063..b62d259fd 100644
--- a/lib/xe/xe_ioctl.h
+++ b/lib/xe/xe_ioctl.h
@@ -91,6 +91,7 @@ void xe_exec_queue_destroy(int fd, uint32_t exec_queue);
 uint64_t xe_bo_mmap_offset(int fd, uint32_t bo);
 void *xe_bo_map(int fd, uint32_t bo, size_t size);
 void *xe_bo_map_fixed(int fd, uint32_t bo, size_t size, uint64_t addr);
+void *xe_bo_map_aligned(int fd, uint32_t bo, size_t size, size_t alignment);
 void *xe_bo_mmap_ext(int fd, uint32_t bo, size_t size, int prot);
 int __xe_exec(int fd, struct drm_xe_exec *exec);
 void xe_exec(int fd, struct drm_xe_exec *exec);
-- 
2.34.1