[igt-dev] [PATCH i-g-t] tests/kms: Return false in gem_has_lmem for platforms not having LMEM support

[Vidya Srinivas]

Starting commit (tests/kms: Create buffer object from LMEM for discrete) it checks
for LMEM. But this is breaking older kernels like 5.4 without
DRM_I915_QUERY_MEMORY_REGIONS support. This causes
item.length filled from IOCTL to be < 0 and gives segmentation
fault. Another way to fix is check for NULL query in
gem_get_lmem_region_count and return false.

Patch returns false from gem_has_lmem for obvious platforms
which dont have LMEM support and also adds the check
for NULL query in gem_get_lmem_region_count.

Signed-off-by: Lin Charlton <charlton.lin at intel.com>
Signed-off-by: Vidya Srinivas <vidya.srinivas at intel.com>
---
 lib/i915/intel_memory_region.c | 7 +++++++
 1 file changed, 7 insertions(+)

diff --git a/lib/i915/intel_memory_region.c b/lib/i915/intel_memory_region.c
index 144ae12ca7a0..635c21ab3765 100644
--- a/lib/i915/intel_memory_region.c
+++ b/lib/i915/intel_memory_region.c
@@ -143,6 +143,10 @@ uint8_t gem_get_lmem_region_count(int fd)
 	uint8_t lmem_regions = 0;
 
 	query_info = gem_get_query_memory_regions(fd);
+
+	if (!query_info)
+		return 0;
+
 	num_regions = query_info->num_regions;
 
 	for (int i = 0; i < num_regions; i++) {
@@ -164,6 +168,9 @@ uint8_t gem_get_lmem_region_count(int fd)
  */
 bool gem_has_lmem(int fd)
 {
+	if (intel_display_ver(intel_get_drm_devid(fd) < 12) ||
+		IS_ALDERLAKE_P(intel_get_drm_devid(fd)) || IS_TIGERLAKE(intel_get_drm_devid(fd)))
+		return false;
 	return gem_get_lmem_region_count(fd) > 0;
 }
 
-- 
2.32.0