drm/xe: Fix exporting xe buffers multiple times

The `struct ttm_resource->placement` contains TTM_PL_FLAG_* flags, but
it was incorrectly tested for XE_PL_* flags.
This caused xe_dma_buf_pin() to always fail when invoked for
the second time. Fix this by checking the `mem_type` field instead.

Fixes: 7764222 ("drm/xe: Disallow pinning dma-bufs in VRAM")
Cc: Thomas Hellström <thomas.hellstrom@linux.intel.com>
Cc: Rodrigo Vivi <rodrigo.vivi@intel.com>
Cc: Lucas De Marchi <lucas.demarchi@intel.com>
Cc: "Thomas Hellström" <thomas.hellstrom@linux.intel.com>
Cc: Michal Wajdeczko <michal.wajdeczko@intel.com>
Cc: Matthew Brost <matthew.brost@intel.com>
Cc: Matthew Auld <matthew.auld@intel.com>
Cc: Nirmoy Das <nirmoy.das@intel.com>
Cc: Jani Nikula <jani.nikula@intel.com>
Cc: intel-xe@lists.freedesktop.org
Cc: <stable@vger.kernel.org> # v6.8+
Signed-off-by: Tomasz Rusinowicz <tomasz.rusinowicz@intel.com>
Signed-off-by: Jacek Lawrynowicz <jacek.lawrynowicz@linux.intel.com>
Reviewed-by: Matthew Brost <matthew.brost@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20250218100353.2137964-1-jacek.lawrynowicz@linux.intel.com
Signed-off-by: Thomas Hellström <thomas.hellstrom@linux.intel.com>
(cherry picked from commit b96dabd)
Signed-off-by: Thomas Hellström <thomas.hellstrom@linux.intel.com>

drivers/gpu/drm/xe/xe_bo.h

@@ -341,7 +341,6 @@ static inline unsigned int xe_sg_segment_size(struct device *dev)
 	return round_down(max / 2, PAGE_SIZE);
 }
 
-#if IS_ENABLED(CONFIG_DRM_XE_KUNIT_TEST)
 /**
  * xe_bo_is_mem_type - Whether the bo currently resides in the given
  * TTM memory type
@@ -356,4 +355,3 @@ static inline bool xe_bo_is_mem_type(struct xe_bo *bo, u32 mem_type)
 	return bo->ttm.resource->mem_type == mem_type;
 }
 #endif
-#endif

drivers/gpu/drm/xe/xe_dma_buf.c

@@ -58,7 +58,7 @@ static int xe_dma_buf_pin(struct dma_buf_attachment *attach)
 	 * 1) Avoid pinning in a placement not accessible to some importers.
 	 * 2) Pinning in VRAM requires PIN accounting which is a to-do.
 	 */
-	if (xe_bo_is_pinned(bo) && bo->ttm.resource->placement != XE_PL_TT) {
+	if (xe_bo_is_pinned(bo) && !xe_bo_is_mem_type(bo, XE_PL_TT)) {
 		drm_dbg(&xe->drm, "Can't migrate pinned bo for dma-buf pin.\n");
 		return -EINVAL;
 	}