drm/i915/uc: Move xfer rsa logic to common function

The way we copy the RSA is the same for GuC and HuC, so we can move the
logic in a common function. this will also make any update needed for
local memory easier.

v2: return the number of copied bytes and check it (Chris)
Signed-off-by: Daniele Ceraolo Spurio <daniele.ceraolospurio@intel.com>
Reviewed-by: Chris Wilson <chris@chris-wilson.co.uk> #v1
Reviewed-by: Michal Wajdeczko <michal.wajdeczko@intel.com>
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Link: https://patchwork.freedesktop.org/patch/msgid/20190725001813.4740-6-daniele.ceraolospurio@intel.com

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

@@ -75,13 +75,12 @@ static void guc_prepare_xfer(struct intel_guc *guc)
 static void guc_xfer_rsa(struct intel_guc *guc)
 {
 	struct intel_uncore *uncore = guc_to_gt(guc)->uncore;
-	struct intel_uc_fw *fw = &guc->fw;
-	struct sg_table *pages = fw->obj->mm.pages;
 	u32 rsa[UOS_RSA_SCRATCH_COUNT];
+	size_t copied;
 	int i;
 
-	sg_pcopy_to_buffer(pages->sgl, pages->nents,
-			   rsa, sizeof(rsa), fw->rsa_offset);
+	copied = intel_uc_fw_copy_rsa(&guc->fw, rsa, sizeof(rsa));
+	GEM_BUG_ON(copied < sizeof(rsa));
 
 	for (i = 0; i < UOS_RSA_SCRATCH_COUNT; i++)
 		intel_uncore_write(uncore, UOS_RSA_SCRATCH(i), rsa[i]);

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

@@ -36,17 +36,17 @@ void intel_huc_fw_init_early(struct intel_huc *huc)
 
 static void huc_xfer_rsa(struct intel_huc *huc)
 {
-	struct intel_uc_fw *fw = &huc->fw;
-	struct sg_table *pages = fw->obj->mm.pages;
+	size_t copied;
 
 	/*
 	 * HuC firmware image is outside GuC accessible range.
 	 * Copy the RSA signature out of the image into
 	 * the perma-pinned region set aside for it
 	 */
-	sg_pcopy_to_buffer(pages->sgl, pages->nents,
-			   huc->rsa_data_vaddr, fw->rsa_size,
-			   fw->rsa_offset);
+	GEM_BUG_ON(huc->fw.rsa_size > huc->rsa_data->size);
+	copied = intel_uc_fw_copy_rsa(&huc->fw, huc->rsa_data_vaddr,
+				      huc->rsa_data->size);
+	GEM_BUG_ON(copied < huc->fw.rsa_size);
 }
 
 static int huc_xfer_ucode(struct intel_huc *huc)

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

@@ -458,6 +458,26 @@ void intel_uc_fw_cleanup_fetch(struct intel_uc_fw *uc_fw)
 	uc_fw->status = INTEL_UC_FIRMWARE_SELECTED;
 }
 
+/**
+ * intel_uc_fw_copy_rsa - copy fw RSA to buffer
+ *
+ * @uc_fw: uC firmware
+ * @dst: dst buffer
+ * @max_len: max number of bytes to copy
+ *
+ * Return: number of copied bytes.
+ */
+size_t intel_uc_fw_copy_rsa(struct intel_uc_fw *uc_fw, void *dst, u32 max_len)
+{
+	struct sg_table *pages = uc_fw->obj->mm.pages;
+	u32 size = min_t(u32, uc_fw->rsa_size, max_len);
+
+	GEM_BUG_ON(!intel_uc_fw_is_available(uc_fw));
+
+	return sg_pcopy_to_buffer(pages->sgl, pages->nents,
+				  dst, size, uc_fw->rsa_offset);
+}
+
 /**
  * intel_uc_fw_dump - dump information about uC firmware
  * @uc_fw: uC firmware

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

@@ -176,6 +176,7 @@ int intel_uc_fw_upload(struct intel_uc_fw *uc_fw,
 int intel_uc_fw_init(struct intel_uc_fw *uc_fw);
 void intel_uc_fw_fini(struct intel_uc_fw *uc_fw);
 u32 intel_uc_fw_ggtt_offset(struct intel_uc_fw *uc_fw);
+size_t intel_uc_fw_copy_rsa(struct intel_uc_fw *uc_fw, void *dst, u32 max_len);
 void intel_uc_fw_dump(const struct intel_uc_fw *uc_fw, struct drm_printer *p);
 
 #endif