drm/i915/uc: Reject duplicate entries in firmware table

It was noticed that duplicate entries in the firmware table could cause
an infinite loop in the firmware loading code if that entry failed to
load. Duplicate entries are a bug anyway and so should never happen.
Ensure they don't by tweaking the table validation code to reject
duplicates.

For full m/m/p files, that can be done by simply tweaking the patch
level check to reject matching values. For reduced version entries,
the filename itself must be compared.

v2: Improve comment (review by Daniele)

Signed-off-by: John Harrison <John.C.Harrison@Intel.com>
Reviewed-by: Daniele Ceraolo Spurio <daniele.ceraolospurio@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20230502234007.1762014-6-John.C.Harrison@Intel.com

drivers/gpu/drm/i915/gt/uc/intel_uc_fw.c

@@ -319,7 +319,7 @@ static bool validate_fw_table_type(struct drm_i915_private *i915, enum intel_uc_
 {
 	const struct uc_fw_platform_requirement *fw_blobs;
 	u32 fw_count;
-	int i;
+	int i, j;
 
 	if (type >= ARRAY_SIZE(blobs_all)) {
 		drm_err(&i915->drm, "No blob array for %s\n", intel_uc_fw_type_repr(type));
@@ -334,6 +334,26 @@ static bool validate_fw_table_type(struct drm_i915_private *i915, enum intel_uc_
 
 	/* make sure the list is ordered as expected */
 	for (i = 1; i < fw_count; i++) {
+		/* Versionless file names must be unique per platform: */
+		for (j = i + 1; j < fw_count; j++) {
+			/* Same platform? */
+			if (fw_blobs[i].p != fw_blobs[j].p)
+				continue;
+
+			if (fw_blobs[i].blob.path != fw_blobs[j].blob.path)
+				continue;
+
+			drm_err(&i915->drm, "Duplicate %s blobs: %s r%u %s%d.%d.%d [%s] matches %s%d.%d.%d [%s]\n",
+				intel_uc_fw_type_repr(type),
+				intel_platform_name(fw_blobs[j].p), fw_blobs[j].rev,
+				fw_blobs[j].blob.legacy ? "L" : "v",
+				fw_blobs[j].blob.major, fw_blobs[j].blob.minor,
+				fw_blobs[j].blob.patch, fw_blobs[j].blob.path,
+				fw_blobs[i].blob.legacy ? "L" : "v",
+				fw_blobs[i].blob.major, fw_blobs[i].blob.minor,
+				fw_blobs[i].blob.patch, fw_blobs[i].blob.path);
+		}
+
 		/* Next platform is good: */
 		if (fw_blobs[i].p < fw_blobs[i - 1].p)
 			continue;
@@ -377,8 +397,8 @@ static bool validate_fw_table_type(struct drm_i915_private *i915, enum intel_uc_
 		if (fw_blobs[i].blob.minor != fw_blobs[i - 1].blob.minor)
 			goto bad;
 
-		/* Patch versions must be in order: */
-		if (fw_blobs[i].blob.patch <= fw_blobs[i - 1].blob.patch)
+		/* Patch versions must be in order and unique: */
+		if (fw_blobs[i].blob.patch < fw_blobs[i - 1].blob.patch)
 			continue;
 
 bad: