firmware: Add the support for ZSTD-compressed firmware files

As the growing demand on ZSTD compressions, there have been requests
for the support of ZSTD-compressed firmware files, so here it is:
this patch extends the firmware loader code to allow loading ZSTD
files.  The implementation is fairly straightforward, it just adds a
ZSTD decompression routine for the file expander.  (And the code is
even simpler than XZ thanks to the ZSTD API that gives the original
decompressed size from the header.)

Link: https://lore.kernel.org/all/20210127154939.13288-1-tiwai@suse.de/Tested-by: Piotr Gorski <lucjan.lucjanov@gmail.com>
Signed-off-by: Takashi Iwai <tiwai@suse.de>
Link: https://lore.kernel.org/r/20220421152908.4718-2-tiwai@suse.deSigned-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/base/firmware_loader/Kconfig

@@ -159,21 +159,33 @@ config FW_LOADER_USER_HELPER_FALLBACK
 
 config FW_LOADER_COMPRESS
 	bool "Enable compressed firmware support"
-	select FW_LOADER_PAGED_BUF
-	select XZ_DEC
 	help
 	  This option enables the support for loading compressed firmware
 	  files. The caller of firmware API receives the decompressed file
 	  content. The compressed file is loaded as a fallback, only after
 	  loading the raw file failed at first.
 
-	  Currently only XZ-compressed files are supported, and they have to
-	  be compressed with either none or crc32 integrity check type (pass
-	  "-C crc32" option to xz command).
-
 	  Compressed firmware support does not apply to firmware images
 	  that are built into the kernel image (CONFIG_EXTRA_FIRMWARE).
 
+if FW_LOADER_COMPRESS
+config FW_LOADER_COMPRESS_XZ
+	bool "Enable XZ-compressed firmware support"
+	select FW_LOADER_PAGED_BUF
+	select XZ_DEC
+	help
+	  This option adds the support for XZ-compressed files.
+	  The files have to be compressed with either none or crc32
+	  integrity check type (pass "-C crc32" option to xz command).
+
+config FW_LOADER_COMPRESS_ZSTD
+	bool "Enable ZSTD-compressed firmware support"
+	select ZSTD_DECOMPRESS
+	help
+	  This option adds the support for ZSTD-compressed files.
+
+endif # FW_LOADER_COMPRESS
+
 config FW_CACHE
 	bool "Enable firmware caching during suspend"
 	depends on PM_SLEEP

drivers/base/firmware_loader/main.c

@@ -35,6 +35,7 @@
 #include <linux/syscore_ops.h>
 #include <linux/reboot.h>
 #include <linux/security.h>
+#include <linux/zstd.h>
 #include <linux/xz.h>
 
 #include <generated/utsrelease.h>
@@ -304,10 +305,74 @@ int fw_map_paged_buf(struct fw_priv *fw_priv)
 }
 #endif
 
+/*
+ * ZSTD-compressed firmware support
+ */
+#ifdef CONFIG_FW_LOADER_COMPRESS_ZSTD
+static int fw_decompress_zstd(struct device *dev, struct fw_priv *fw_priv,
+			      size_t in_size, const void *in_buffer)
+{
+	size_t len, out_size, workspace_size;
+	void *workspace, *out_buf;
+	zstd_dctx *ctx;
+	int err;
+
+	if (fw_priv->allocated_size) {
+		out_size = fw_priv->allocated_size;
+		out_buf = fw_priv->data;
+	} else {
+		zstd_frame_header params;
+
+		if (zstd_get_frame_header(&params, in_buffer, in_size) ||
+		    params.frameContentSize == ZSTD_CONTENTSIZE_UNKNOWN) {
+			dev_dbg(dev, "%s: invalid zstd header\n", __func__);
+			return -EINVAL;
+		}
+		out_size = params.frameContentSize;
+		out_buf = vzalloc(out_size);
+		if (!out_buf)
+			return -ENOMEM;
+	}
+
+	workspace_size = zstd_dctx_workspace_bound();
+	workspace = kvzalloc(workspace_size, GFP_KERNEL);
+	if (!workspace) {
+		err = -ENOMEM;
+		goto error;
+	}
+
+	ctx = zstd_init_dctx(workspace, workspace_size);
+	if (!ctx) {
+		dev_dbg(dev, "%s: failed to initialize context\n", __func__);
+		err = -EINVAL;
+		goto error;
+	}
+
+	len = zstd_decompress_dctx(ctx, out_buf, out_size, in_buffer, in_size);
+	if (zstd_is_error(len)) {
+		dev_dbg(dev, "%s: failed to decompress: %d\n", __func__,
+			zstd_get_error_code(len));
+		err = -EINVAL;
+		goto error;
+	}
+
+	if (!fw_priv->allocated_size)
+		fw_priv->data = out_buf;
+	fw_priv->size = len;
+	err = 0;
+
+ error:
+	kvfree(workspace);
+	if (err && !fw_priv->allocated_size)
+		vfree(out_buf);
+	return err;
+}
+#endif /* CONFIG_FW_LOADER_COMPRESS_ZSTD */
+
 /*
  * XZ-compressed firmware support
  */
-#ifdef CONFIG_FW_LOADER_COMPRESS
+#ifdef CONFIG_FW_LOADER_COMPRESS_XZ
 /* show an error and return the standard error code */
 static int fw_decompress_xz_error(struct device *dev, enum xz_ret xz_ret)
 {
@@ -401,7 +466,7 @@ static int fw_decompress_xz(struct device *dev, struct fw_priv *fw_priv,
 	else
 		return fw_decompress_xz_pages(dev, fw_priv, in_size, in_buffer);
 }
-#endif /* CONFIG_FW_LOADER_COMPRESS */
+#endif /* CONFIG_FW_LOADER_COMPRESS_XZ */
 
 /* direct firmware loading support */
 static char fw_path_para[256];
@@ -757,7 +822,12 @@ _request_firmware(const struct firmware **firmware_p, const char *name,
 	if (!(opt_flags & FW_OPT_PARTIAL))
 		nondirect = true;
 
-#ifdef CONFIG_FW_LOADER_COMPRESS
+#ifdef CONFIG_FW_LOADER_COMPRESS_ZSTD
+	if (ret == -ENOENT && nondirect)
+		ret = fw_get_filesystem_firmware(device, fw->priv, ".zst",
+						 fw_decompress_zstd);
+#endif
+#ifdef CONFIG_FW_LOADER_COMPRESS_XZ
 	if (ret == -ENOENT && nondirect)
 		ret = fw_get_filesystem_firmware(device, fw->priv, ".xz",
 						 fw_decompress_xz);