diff --git a/Documentation/DocBook/drm.tmpl b/Documentation/DocBook/drm.tmpl
index 66bc646..4d8dffb 100644
--- a/Documentation/DocBook/drm.tmpl
+++ b/Documentation/DocBook/drm.tmpl
@@ -4155,14 +4155,19 @@ int num_ioctls;</synopsis>
       <title>GuC-based Command Submission</title>
       <sect2>
         <title>GuC</title>
-!Pdrivers/gpu/drm/i915/intel_guc_loader.c GuC-specific firmware loader
+!Pdrivers/gpu/drm/i915/intel_guc_loader.c GuC
 !Idrivers/gpu/drm/i915/intel_guc_loader.c
       </sect2>
       <sect2>
         <title>GuC Client</title>
-!Pdrivers/gpu/drm/i915/i915_guc_submission.c GuC-based command submissison
+!Pdrivers/gpu/drm/i915/i915_guc_submission.c GuC Client
 !Idrivers/gpu/drm/i915/i915_guc_submission.c
       </sect2>
+      <sect2>
+        <title>GuC Firmware Layout</title>
+!Pdrivers/gpu/drm/i915/intel_guc_fwif.h GuC Firmware Layout
+!Idrivers/gpu/drm/i915/intel_guc_fwif.h
+      </sect2>
     </sect1>
 
     <sect1>
diff --git a/drivers/gpu/drm/i915/i915_debugfs.c b/drivers/gpu/drm/i915/i915_debugfs.c
index 5615d3d..0753b2f 100644
--- a/drivers/gpu/drm/i915/i915_debugfs.c
+++ b/drivers/gpu/drm/i915/i915_debugfs.c
@@ -2386,9 +2386,15 @@ static int i915_guc_load_status_info(struct seq_file *m, void *data)
 	seq_printf(m, "\tload: %s\n",
 		intel_guc_fw_status_repr(guc_fw->guc_fw_load_status));
 	seq_printf(m, "\tversion wanted: %d.%d\n",
-		guc_fw->guc_fw_major_wanted, guc_fw->guc_fw_minor_wanted);
+		guc_fw->ver_major_wanted, guc_fw->ver_minor_wanted);
 	seq_printf(m, "\tversion found: %d.%d\n",
-		guc_fw->guc_fw_major_found, guc_fw->guc_fw_minor_found);
+		guc_fw->ver_major_found, guc_fw->ver_minor_found);
+	seq_printf(m, "\theader: offset is %d; size = %d\n",
+		guc_fw->header_offset, guc_fw->header_size);
+	seq_printf(m, "\tuCode: offset is %d; size = %d\n",
+		guc_fw->ucode_offset, guc_fw->ucode_size);
+	seq_printf(m, "\tRSA: offset is %d; size = %d\n",
+		guc_fw->rsa_offset, guc_fw->rsa_size);
 
 	tmp = I915_READ(GUC_STATUS);
 
diff --git a/drivers/gpu/drm/i915/i915_guc_reg.h b/drivers/gpu/drm/i915/i915_guc_reg.h
index b355661..578739d 100644
--- a/drivers/gpu/drm/i915/i915_guc_reg.h
+++ b/drivers/gpu/drm/i915/i915_guc_reg.h
@@ -42,6 +42,7 @@
 #define SOFT_SCRATCH(n)			(0xc180 + ((n) * 4))
 
 #define UOS_RSA_SCRATCH_0		0xc200
+#define   UOS_RSA_SCRATCH_MAX_COUNT	  64
 #define DMA_ADDR_0_LOW			0xc300
 #define DMA_ADDR_0_HIGH			0xc304
 #define DMA_ADDR_1_LOW			0xc308
diff --git a/drivers/gpu/drm/i915/intel_guc.h b/drivers/gpu/drm/i915/intel_guc.h
index 4ec2d27..55c9bf8 100644
--- a/drivers/gpu/drm/i915/intel_guc.h
+++ b/drivers/gpu/drm/i915/intel_guc.h
@@ -72,15 +72,21 @@ struct intel_guc_fw {
 	enum intel_guc_fw_status	guc_fw_fetch_status;
 	enum intel_guc_fw_status	guc_fw_load_status;
 
-	uint16_t			guc_fw_major_wanted;
-	uint16_t			guc_fw_minor_wanted;
-	uint16_t			guc_fw_major_found;
-	uint16_t			guc_fw_minor_found;
+	uint32_t header_size;
+	uint32_t header_offset;
+	uint32_t rsa_size;
+	uint32_t rsa_offset;
+	uint32_t ucode_size;
+	uint32_t ucode_offset;
+
+	uint16_t ver_major_wanted;
+	uint16_t ver_minor_wanted;
+	uint16_t ver_major_found;
+	uint16_t ver_minor_found;
 };
 
 struct intel_guc {
 	struct intel_guc_fw guc_fw;
-
 	uint32_t log_flags;
 	struct drm_i915_gem_object *log_obj;
 
diff --git a/drivers/gpu/drm/i915/intel_guc_fwif.h b/drivers/gpu/drm/i915/intel_guc_fwif.h
index e1f47ba..cd94075 100644
--- a/drivers/gpu/drm/i915/intel_guc_fwif.h
+++ b/drivers/gpu/drm/i915/intel_guc_fwif.h
@@ -122,6 +122,78 @@
 
 #define GUC_CTL_MAX_DWORDS		(GUC_CTL_RSRVD + 1)
 
+/**
+ * DOC: GuC Firmware Layout
+ *
+ * The GuC firmware layout looks like this:
+ *
+ *     +-------------------------------+
+ *     |        guc_css_header         |
+ *     | contains major/minor version  |
+ *     +-------------------------------+
+ *     |             uCode             |
+ *     +-------------------------------+
+ *     |         RSA signature         |
+ *     +-------------------------------+
+ *     |          modulus key          |
+ *     +-------------------------------+
+ *     |          exponent val         |
+ *     +-------------------------------+
+ *
+ * The firmware may or may not have modulus key and exponent data. The header,
+ * uCode and RSA signature are must-have components that will be used by driver.
+ * Length of each components, which is all in dwords, can be found in header.
+ * In the case that modulus and exponent are not present in fw, a.k.a truncated
+ * image, the length value still appears in header.
+ *
+ * Driver will do some basic fw size validation based on the following rules:
+ *
+ * 1. Header, uCode and RSA are must-have components.
+ * 2. All firmware components, if they present, are in the sequence illustrated
+ * in the layout table above.
+ * 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.
+*/
+
+struct guc_css_header {
+	uint32_t module_type;
+	 /* header_len includes all non-uCode bits, which is:
+	  * < css_header + key_len + modulus_len + exponent_len > */
+	uint32_t header_len;
+	uint32_t header_version;
+	uint32_t module_id;
+	uint32_t module_vendor;
+	union {
+		struct {
+			uint8_t day;
+			uint8_t month;
+			uint16_t year;
+		};
+		uint32_t date;
+	};
+	uint32_t length; /* uCode length plus header_len */
+	uint32_t key_len;
+	uint32_t modulus_len;
+	uint32_t exponent_len;
+	union {
+		struct {
+			uint8_t hour;
+			uint8_t min;
+			uint16_t sec;
+		};
+		uint32_t time;
+	};
+
+	char username[8];
+	char buildnumber[12];
+	uint32_t device_id;
+	uint32_t guc_sw_version;
+	uint32_t prod_preprod_fw;
+	uint32_t reserved[12];
+	uint32_t header_info;
+} __packed;
+
 struct guc_doorbell_info {
 	u32 db_status;
 	u32 cookie;
diff --git a/drivers/gpu/drm/i915/intel_guc_loader.c b/drivers/gpu/drm/i915/intel_guc_loader.c
index 40241f3..e2813d4 100644
--- a/drivers/gpu/drm/i915/intel_guc_loader.c
+++ b/drivers/gpu/drm/i915/intel_guc_loader.c
@@ -218,16 +218,6 @@ static inline bool guc_ucode_response(struct drm_i915_private *dev_priv,
 /*
  * Transfer the firmware image to RAM for execution by the microcontroller.
  *
- * GuC Firmware layout:
- * +-------------------------------+  ----
- * |          CSS header           |  128B
- * | contains major/minor version  |
- * +-------------------------------+  ----
- * |             uCode             |
- * +-------------------------------+  ----
- * |         RSA signature         |  256B
- * +-------------------------------+  ----
- *
  * Architecturally, the DMA engine is bidirectional, and can potentially even
  * transfer between GTT locations. This functionality is left out of the API
  * for now as there is no need for it.
@@ -235,33 +225,29 @@ static inline bool guc_ucode_response(struct drm_i915_private *dev_priv,
  * Note that GuC needs the CSS header plus uKernel code to be copied by the
  * DMA engine in one operation, whereas the RSA signature is loaded via MMIO.
  */
-
-#define UOS_CSS_HEADER_OFFSET		0
-#define UOS_VER_MINOR_OFFSET		0x44
-#define UOS_VER_MAJOR_OFFSET		0x46
-#define UOS_CSS_HEADER_SIZE		0x80
-#define UOS_RSA_SIG_SIZE		0x100
-
 static int guc_ucode_xfer_dma(struct drm_i915_private *dev_priv)
 {
 	struct intel_guc_fw *guc_fw = &dev_priv->guc.guc_fw;
 	struct drm_i915_gem_object *fw_obj = guc_fw->guc_fw_obj;
 	unsigned long offset;
 	struct sg_table *sg = fw_obj->pages;
-	u32 status, ucode_size, rsa[UOS_RSA_SIG_SIZE / sizeof(u32)];
+	u32 status, rsa[UOS_RSA_SCRATCH_MAX_COUNT];
 	int i, ret = 0;
 
-	/* uCode size, also is where RSA signature starts */
-	offset = ucode_size = guc_fw->guc_fw_size - UOS_RSA_SIG_SIZE;
-	I915_WRITE(DMA_COPY_SIZE, ucode_size);
+	/* where RSA signature starts */
+	offset = guc_fw->rsa_offset;
 
 	/* Copy RSA signature from the fw image to HW for verification */
-	sg_pcopy_to_buffer(sg->sgl, sg->nents, rsa, UOS_RSA_SIG_SIZE, offset);
-	for (i = 0; i < UOS_RSA_SIG_SIZE / sizeof(u32); i++)
+	sg_pcopy_to_buffer(sg->sgl, sg->nents, rsa, sizeof(rsa), offset);
+	for (i = 0; i < UOS_RSA_SCRATCH_MAX_COUNT; i++)
 		I915_WRITE(UOS_RSA_SCRATCH_0 + i * sizeof(u32), rsa[i]);
 
+	/* The header plus uCode will be copied to WOPCM via DMA, excluding any
+	 * other components */
+	I915_WRITE(DMA_COPY_SIZE, guc_fw->header_size + guc_fw->ucode_size);
+
 	/* Set the source address for the new blob */
-	offset = i915_gem_obj_ggtt_offset(fw_obj);
+	offset = i915_gem_obj_ggtt_offset(fw_obj) + guc_fw->header_offset;
 	I915_WRITE(DMA_ADDR_0_LOW, lower_32_bits(offset));
 	I915_WRITE(DMA_ADDR_0_HIGH, upper_32_bits(offset) & 0xFFFF);
 
@@ -465,10 +451,8 @@ static void guc_fw_fetch(struct drm_device *dev, struct intel_guc_fw *guc_fw)
 {
 	struct drm_i915_gem_object *obj;
 	const struct firmware *fw;
-	const u8 *css_header;
-	const size_t minsize = UOS_CSS_HEADER_SIZE + UOS_RSA_SIG_SIZE;
-	const size_t maxsize = GUC_WOPCM_SIZE_VALUE + UOS_RSA_SIG_SIZE
-			- 0x8000; /* 32k reserved (8K stack + 24k context) */
+	struct guc_css_header *css_header;
+	size_t size;
 	int err;
 
 	DRM_DEBUG_DRIVER("before requesting firmware: GuC fw fetch status %s\n",
@@ -482,12 +466,53 @@ static void guc_fw_fetch(struct drm_device *dev, struct intel_guc_fw *guc_fw)
 
 	DRM_DEBUG_DRIVER("fetch GuC fw from %s succeeded, fw %p\n",
 		guc_fw->guc_fw_path, fw);
-	DRM_DEBUG_DRIVER("firmware file size %zu (minimum %zu, maximum %zu)\n",
-		fw->size, minsize, maxsize);
 
-	/* Check the size of the blob befoe examining buffer contents */
-	if (fw->size < minsize || fw->size > maxsize)
+	/* Check the size of the blob before examining buffer contents */
+	if (fw->size < sizeof(struct guc_css_header)) {
+		DRM_ERROR("Firmware header is missing\n");
 		goto fail;
+	}
+
+	css_header = (struct guc_css_header *)fw->data;
+
+	/* Firmware bits always start from header */
+	guc_fw->header_offset = 0;
+	guc_fw->header_size = (css_header->header_len - css_header->modulus_len
+		- css_header->key_len - css_header->exponent_len) * sizeof(u32);
+
+	if (guc_fw->header_size != sizeof(struct guc_css_header)) {
+		DRM_ERROR("CSS header definition mismatch\n");
+		goto fail;
+	}
+
+	/* then, uCode */
+	guc_fw->ucode_offset = guc_fw->header_offset + guc_fw->header_size;
+	guc_fw->ucode_size =
+		(css_header->length - css_header->header_len) * sizeof(u32);
+
+	/* now RSA */
+	if (css_header->key_len != UOS_RSA_SCRATCH_MAX_COUNT) {
+		DRM_ERROR("RSA key size is bad\n");
+		goto fail;
+	}
+	guc_fw->rsa_offset = guc_fw->ucode_offset + guc_fw->ucode_size;
+	guc_fw->rsa_size = css_header->key_len * sizeof(u32);
+
+	/* At least, it should have header, uCode and RSA. Size of all three. */
+	size = guc_fw->header_size + guc_fw->ucode_size + guc_fw->rsa_size;
+	if (fw->size < size) {
+		DRM_ERROR("Missing firmware components\n");
+		goto fail;
+	}
+
+	/* Header and uCode will be loaded to WOPCM. Size of the two. */
+	size = guc_fw->header_size + guc_fw->ucode_size;
+
+	/* Top 32k of WOPCM is reserved (8K stack + 24k RC6 context). */
+	if (size > GUC_WOPCM_SIZE_VALUE - 0x8000) {
+		DRM_ERROR("Firmware is too large to fit in WOPCM\n");
+		goto fail;
+	}
 
 	/*
 	 * The GuC firmware image has the version number embedded at a well-known
@@ -495,22 +520,21 @@ static void guc_fw_fetch(struct drm_device *dev, struct intel_guc_fw *guc_fw)
 	 * TWO bytes each (i.e. u16), although all pointers and offsets are defined
 	 * in terms of bytes (u8).
 	 */
-	css_header = fw->data + UOS_CSS_HEADER_OFFSET;
-	guc_fw->guc_fw_major_found = *(u16 *)(css_header + UOS_VER_MAJOR_OFFSET);
-	guc_fw->guc_fw_minor_found = *(u16 *)(css_header + UOS_VER_MINOR_OFFSET);
+	guc_fw->ver_major_found = css_header->guc_sw_version >> 16;
+	guc_fw->ver_minor_found = css_header->guc_sw_version & 0xFFFF;
 
-	if (guc_fw->guc_fw_major_found != guc_fw->guc_fw_major_wanted ||
-	    guc_fw->guc_fw_minor_found < guc_fw->guc_fw_minor_wanted) {
+	if (guc_fw->ver_major_found != guc_fw->ver_major_wanted ||
+	    guc_fw->ver_minor_found < guc_fw->ver_minor_wanted) {
 		DRM_ERROR("GuC firmware version %d.%d, required %d.%d\n",
-			guc_fw->guc_fw_major_found, guc_fw->guc_fw_minor_found,
-			guc_fw->guc_fw_major_wanted, guc_fw->guc_fw_minor_wanted);
+			guc_fw->ver_major_found, guc_fw->ver_minor_found,
+			guc_fw->ver_major_wanted, guc_fw->ver_minor_wanted);
 		err = -ENOEXEC;
 		goto fail;
 	}
 
 	DRM_DEBUG_DRIVER("firmware version %d.%d OK (minimum %d.%d)\n",
-			guc_fw->guc_fw_major_found, guc_fw->guc_fw_minor_found,
-			guc_fw->guc_fw_major_wanted, guc_fw->guc_fw_minor_wanted);
+			guc_fw->ver_major_found, guc_fw->ver_minor_found,
+			guc_fw->ver_major_wanted, guc_fw->ver_minor_wanted);
 
 	obj = i915_gem_object_create_from_data(dev, fw->data, fw->size);
 	if (IS_ERR_OR_NULL(obj)) {
@@ -567,8 +591,8 @@ void intel_guc_ucode_init(struct drm_device *dev)
 		fw_path = NULL;
 	} else if (IS_SKYLAKE(dev)) {
 		fw_path = I915_SKL_GUC_UCODE;
-		guc_fw->guc_fw_major_wanted = 4;
-		guc_fw->guc_fw_minor_wanted = 3;
+		guc_fw->ver_major_wanted = 4;
+		guc_fw->ver_minor_wanted = 3;
 	} else {
 		i915.enable_guc_submission = false;
 		fw_path = "";	/* unknown device */
