drm/i915/uc: Enhancements to firmware table validation

The validation of the firmware table was being done inside the code
for scanning the table for the next available firmware blob. Which is
unnecessary. So pull it out into a separate function that is only
called once per blob type at init time.

Also, drop the CONFIG_SELFTEST requirement and make errors terminal.
It was mentioned that potential issues with backports would not be
caught by regular pre-merge CI as that only occurs on tip not stable
branches. Making the validation unconditional and failing driver load
on detecting of a problem ensures that such backports will also be
validated correctly.

This requires adding a firmware global flag to indicate an issue with
any of the per firmware tables. This is done rather than adding a new
state enum as a new enum value would be a much more invasive change -
lots of places would need updating to support the new error state.

Note also that this change means that a table error will cause the
driver to wedge even on platforms that don't require firmware files.
This is intentional as per the above backport concern - someone doing
backports is not guaranteed to test on every platform that they may
potential affect. So forcing a failure on all platforms ensures that
the problem will be noticed and corrected immediately.

v2: Change to unconditionally fail module load on a validation error
(review feedback/discussion with Daniele).
v3: Add a new flag to track table validation errors (review
feedback/discussion with 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/20230502234007.1762014-5-John.C.Harrison@Intel.com

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

@@ -432,6 +432,9 @@ static bool uc_is_wopcm_locked(struct intel_uc *uc)
 
 static int __uc_check_hw(struct intel_uc *uc)
 {
+	if (uc->fw_table_invalid)
+		return -EIO;
+
 	if (!intel_uc_supports_guc(uc))
 		return 0;
 

drivers/gpu/drm/i915/gt/uc/intel_uc.h

@@ -36,6 +36,7 @@ struct intel_uc {
 	struct drm_i915_gem_object *load_err_log;
 
 	bool reset_in_progress;
+	bool fw_table_invalid;
 };
 
 void intel_uc_init_early(struct intel_uc *uc);

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

@@ -233,20 +233,22 @@ struct fw_blobs_by_type {
 	u32 count;
 };
 
-static void
-__uc_fw_auto_select(struct drm_i915_private *i915, struct intel_uc_fw *uc_fw)
-{
-	static const struct uc_fw_platform_requirement blobs_guc[] = {
+static const struct uc_fw_platform_requirement blobs_guc[] = {
 	INTEL_GUC_FIRMWARE_DEFS(MAKE_FW_LIST, GUC_FW_BLOB, GUC_FW_BLOB_MMP)
-	};
-	static const struct uc_fw_platform_requirement blobs_huc[] = {
+};
+
+static const struct uc_fw_platform_requirement blobs_huc[] = {
 	INTEL_HUC_FIRMWARE_DEFS(MAKE_FW_LIST, HUC_FW_BLOB, HUC_FW_BLOB_MMP, HUC_FW_BLOB_GSC)
-	};
-	static const struct fw_blobs_by_type blobs_all[INTEL_UC_FW_NUM_TYPES] = {
+};
+
+static const struct fw_blobs_by_type blobs_all[INTEL_UC_FW_NUM_TYPES] = {
 	[INTEL_UC_FW_TYPE_GUC] = { blobs_guc, ARRAY_SIZE(blobs_guc) },
 	[INTEL_UC_FW_TYPE_HUC] = { blobs_huc, ARRAY_SIZE(blobs_huc) },
-	};
-	static bool verified[INTEL_UC_FW_NUM_TYPES];
+};
+
+static void
+__uc_fw_auto_select(struct drm_i915_private *i915, struct intel_uc_fw *uc_fw)
+{
 	const struct uc_fw_platform_requirement *fw_blobs;
 	enum intel_platform p = INTEL_INFO(i915)->platform;
 	u32 fw_count;
@@ -286,6 +288,11 @@ __uc_fw_auto_select(struct drm_i915_private *i915, struct intel_uc_fw *uc_fw)
 			continue;
 
 		if (uc_fw->file_selected.path) {
+			/*
+			 * Continuing an earlier search after a found blob failed to load.
+			 * Once the previously chosen path has been found, clear it out
+			 * and let the search continue from there.
+			 */
 			if (uc_fw->file_selected.path == blob->path)
 				uc_fw->file_selected.path = NULL;
 
@@ -306,11 +313,26 @@ __uc_fw_auto_select(struct drm_i915_private *i915, struct intel_uc_fw *uc_fw)
 		/* Failed to find a match for the last attempt?! */
 		uc_fw->file_selected.path = NULL;
 	}
+}
 
-	/* make sure the list is ordered as expected */
-	if (IS_ENABLED(CONFIG_DRM_I915_SELFTEST) && !verified[uc_fw->type]) {
-		verified[uc_fw->type] = true;
+static bool validate_fw_table_type(struct drm_i915_private *i915, enum intel_uc_fw_type type)
+{
+	const struct uc_fw_platform_requirement *fw_blobs;
+	u32 fw_count;
+	int i;
+
+	if (type >= ARRAY_SIZE(blobs_all)) {
+		drm_err(&i915->drm, "No blob array for %s\n", intel_uc_fw_type_repr(type));
+		return false;
+	}
 
+	fw_blobs = blobs_all[type].blobs;
+	fw_count = blobs_all[type].count;
+
+	if (!fw_count)
+		return true;
+
+	/* make sure the list is ordered as expected */
 	for (i = 1; i < fw_count; i++) {
 		/* Next platform is good: */
 		if (fw_blobs[i].p < fw_blobs[i - 1].p)
@@ -361,7 +383,7 @@ __uc_fw_auto_select(struct drm_i915_private *i915, struct intel_uc_fw *uc_fw)
 
 bad:
 		drm_err(&i915->drm, "Invalid %s blob order: %s r%u %s%d.%d.%d comes before %s r%u %s%d.%d.%d\n",
-				intel_uc_fw_type_repr(uc_fw->type),
+			intel_uc_fw_type_repr(type),
 			intel_platform_name(fw_blobs[i - 1].p), fw_blobs[i - 1].rev,
 			fw_blobs[i - 1].blob.legacy ? "L" : "v",
 			fw_blobs[i - 1].blob.major,
@@ -372,10 +394,10 @@ __uc_fw_auto_select(struct drm_i915_private *i915, struct intel_uc_fw *uc_fw)
 			fw_blobs[i].blob.major,
 			fw_blobs[i].blob.minor,
 			fw_blobs[i].blob.patch);
-
-			uc_fw->file_selected.path = NULL;
-		}
+		return false;
 	}
+
+	return true;
 }
 
 static const char *__override_guc_firmware_path(struct drm_i915_private *i915)
@@ -430,7 +452,8 @@ static void __uc_fw_user_override(struct drm_i915_private *i915, struct intel_uc
 void intel_uc_fw_init_early(struct intel_uc_fw *uc_fw,
 			    enum intel_uc_fw_type type)
 {
-	struct drm_i915_private *i915 = ____uc_fw_to_gt(uc_fw, type)->i915;
+	struct intel_gt *gt = ____uc_fw_to_gt(uc_fw, type);
+	struct drm_i915_private *i915 = gt->i915;
 
 	/*
 	 * we use FIRMWARE_UNINITIALIZED to detect checks against uc_fw->status
@@ -443,6 +466,12 @@ void intel_uc_fw_init_early(struct intel_uc_fw *uc_fw,
 	uc_fw->type = type;
 
 	if (HAS_GT_UC(i915)) {
+		if (!validate_fw_table_type(i915, type)) {
+			gt->uc.fw_table_invalid = true;
+			intel_uc_fw_change_status(uc_fw, INTEL_UC_FIRMWARE_NOT_SUPPORTED);
+			return;
+		}
+
 		__uc_fw_auto_select(i915, uc_fw);
 		__uc_fw_user_override(i915, uc_fw);
 	}