drm/i915/huc: Add fetch support for gsc-loaded HuC binary

On newer platforms (starting DG2 G10 B-step and G11 A-step), ownership of
HuC loading has been moved from the GuC to the GSC. As part of the
change, the header format of the HuC binary has been updated and does not
match the GuC anymore. The GSC will perform all the required checks on
the binary size, so we only need to check that the version matches.

Note that since we still haven't added any gsc-loaded FWs, the
loaded_via_gsc variable will always be kept to its initialization value
of zero.

v2: Add a note about loaded_via_gsc being zero (Alan)
Signed-off-by: Daniele Ceraolo Spurio <daniele.ceraolospurio@intel.com>
Reviewed-by: Alan Previn <alan.previn.teres.alexis@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20220504204816.2082588-3-daniele.ceraolospurio@intel.com

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

@@ -301,45 +301,31 @@ static void __force_fw_fetch_failures(struct intel_uc_fw *uc_fw, int e)
 	}
 }
 
-/**
- * intel_uc_fw_fetch - fetch uC firmware
- * @uc_fw: uC firmware
- *
- * Fetch uC firmware into GEM obj.
- *
- * Return: 0 on success, a negative errno code on failure.
- */
-int intel_uc_fw_fetch(struct intel_uc_fw *uc_fw)
+static int check_gsc_manifest(const struct firmware *fw,
+			      struct intel_uc_fw *uc_fw)
 {
-	struct drm_i915_private *i915 = __uc_fw_to_gt(uc_fw)->i915;
-	struct device *dev = i915->drm.dev;
-	struct drm_i915_gem_object *obj;
-	const struct firmware *fw = NULL;
-	struct uc_css_header *css;
-	size_t size;
-	int err;
+	u32 *dw = (u32 *)fw->data;
+	u32 version = dw[HUC_GSC_VERSION_DW];
 
-	GEM_BUG_ON(!i915->wopcm.size);
-	GEM_BUG_ON(!intel_uc_fw_is_enabled(uc_fw));
-
-	err = i915_inject_probe_error(i915, -ENXIO);
-	if (err)
-		goto fail;
+	uc_fw->major_ver_found = FIELD_GET(HUC_GSC_MAJOR_VER_MASK, version);
+	uc_fw->minor_ver_found = FIELD_GET(HUC_GSC_MINOR_VER_MASK, version);
 
-	__force_fw_fetch_failures(uc_fw, -EINVAL);
-	__force_fw_fetch_failures(uc_fw, -ESTALE);
+	return 0;
+}
 
-	err = request_firmware(&fw, uc_fw->path, dev);
-	if (err)
-		goto fail;
+static int check_ccs_header(struct drm_i915_private *i915,
+			    const struct firmware *fw,
+			    struct intel_uc_fw *uc_fw)
+{
+	struct uc_css_header *css;
+	size_t size;
 
 	/* Check the size of the blob before examining buffer contents */
 	if (unlikely(fw->size < sizeof(struct uc_css_header))) {
 		drm_warn(&i915->drm, "%s firmware %s: invalid size: %zu < %zu\n",
 			 intel_uc_fw_type_repr(uc_fw->type), uc_fw->path,
 			 fw->size, sizeof(struct uc_css_header));
-		err = -ENODATA;
-		goto fail;
+		return -ENODATA;
 	}
 
 	css = (struct uc_css_header *)fw->data;
@@ -352,8 +338,7 @@ int intel_uc_fw_fetch(struct intel_uc_fw *uc_fw)
 			 "%s firmware %s: unexpected header size: %zu != %zu\n",
 			 intel_uc_fw_type_repr(uc_fw->type), uc_fw->path,
 			 fw->size, sizeof(struct uc_css_header));
-		err = -EPROTO;
-		goto fail;
+		return -EPROTO;
 	}
 
 	/* uCode size must calculated from other sizes */
@@ -368,8 +353,7 @@ int intel_uc_fw_fetch(struct intel_uc_fw *uc_fw)
 		drm_warn(&i915->drm, "%s firmware %s: invalid size: %zu < %zu\n",
 			 intel_uc_fw_type_repr(uc_fw->type), uc_fw->path,
 			 fw->size, size);
-		err = -ENOEXEC;
-		goto fail;
+		return -ENOEXEC;
 	}
 
 	/* Sanity check whether this fw is not larger than whole WOPCM memory */
@@ -378,8 +362,7 @@ int intel_uc_fw_fetch(struct intel_uc_fw *uc_fw)
 		drm_warn(&i915->drm, "%s firmware %s: invalid size: %zu > %zu\n",
 			 intel_uc_fw_type_repr(uc_fw->type), uc_fw->path,
 			 size, (size_t)i915->wopcm.size);
-		err = -E2BIG;
-		goto fail;
+		return -E2BIG;
 	}
 
 	/* Get version numbers from the CSS header */
@@ -388,6 +371,49 @@ int intel_uc_fw_fetch(struct intel_uc_fw *uc_fw)
 	uc_fw->minor_ver_found = FIELD_GET(CSS_SW_VERSION_UC_MINOR,
 					   css->sw_version);
 
+	if (uc_fw->type == INTEL_UC_FW_TYPE_GUC)
+		uc_fw->private_data_size = css->private_data_size;
+
+	return 0;
+}
+
+/**
+ * intel_uc_fw_fetch - fetch uC firmware
+ * @uc_fw: uC firmware
+ *
+ * Fetch uC firmware into GEM obj.
+ *
+ * Return: 0 on success, a negative errno code on failure.
+ */
+int intel_uc_fw_fetch(struct intel_uc_fw *uc_fw)
+{
+	struct drm_i915_private *i915 = __uc_fw_to_gt(uc_fw)->i915;
+	struct device *dev = i915->drm.dev;
+	struct drm_i915_gem_object *obj;
+	const struct firmware *fw = NULL;
+	int err;
+
+	GEM_BUG_ON(!i915->wopcm.size);
+	GEM_BUG_ON(!intel_uc_fw_is_enabled(uc_fw));
+
+	err = i915_inject_probe_error(i915, -ENXIO);
+	if (err)
+		goto fail;
+
+	__force_fw_fetch_failures(uc_fw, -EINVAL);
+	__force_fw_fetch_failures(uc_fw, -ESTALE);
+
+	err = request_firmware(&fw, uc_fw->path, dev);
+	if (err)
+		goto fail;
+
+	if (uc_fw->loaded_via_gsc)
+		err = check_gsc_manifest(fw, uc_fw);
+	else
+		err = check_ccs_header(i915, fw, uc_fw);
+	if (err)
+		goto fail;
+
 	if (uc_fw->major_ver_found != uc_fw->major_ver_wanted ||
 	    uc_fw->minor_ver_found < uc_fw->minor_ver_wanted) {
 		drm_notice(&i915->drm, "%s firmware %s: unexpected version: %u.%u != %u.%u\n",
@@ -400,9 +426,6 @@ int intel_uc_fw_fetch(struct intel_uc_fw *uc_fw)
 		}
 	}
 
-	if (uc_fw->type == INTEL_UC_FW_TYPE_GUC)
-		uc_fw->private_data_size = css->private_data_size;
-
 	if (HAS_LMEM(i915)) {
 		obj = i915_gem_object_create_lmem_from_data(i915, fw->data, fw->size);
 		if (!IS_ERR(obj))

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

@@ -102,6 +102,8 @@ struct intel_uc_fw {
 	u32 ucode_size;
 
 	u32 private_data_size;
+
+	bool loaded_via_gsc;
 };
 
 #ifdef CONFIG_DRM_I915_DEBUG_GUC

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

@@ -39,6 +39,11 @@
  * 3. Length info of each component can be found in header, in dwords.
  * 4. Modulus and exponent key are not required by driver. They may not appear
  *    in fw. So driver will load a truncated firmware in this case.
+ *
+ * Starting from DG2, the HuC is loaded by the GSC instead of i915. The GSC
+ * firmware performs all the required integrity checks, we just need to check
+ * the version. Note that the header for GSC-managed blobs is different from the
+ * CSS used for dma-loaded firmwares.
  */
 
 struct uc_css_header {
@@ -78,4 +83,8 @@ struct uc_css_header {
 } __packed;
 static_assert(sizeof(struct uc_css_header) == 128);
 
+#define HUC_GSC_VERSION_DW		44
+#define   HUC_GSC_MAJOR_VER_MASK	(0xFF << 0)
+#define   HUC_GSC_MINOR_VER_MASK	(0xFF << 16)
+
 #endif /* _INTEL_UC_FW_ABI_H */