Re: [PATCH v5 2/2] drm/xe/guc: Compress GuC log and CTB dump with zstd

[Julia Filipchuk <julia.filipchuk@intel.com>]

Patch looks generally good.

Please check deallocation in xe_guc_print_blob_compressed().

Please remove added build files.
>  kernel/build64-debug/Makefile             |   3 +
>  kernel/build64-debug/scripts/basic/fixdep | Bin 0 -> 16936 bytes



On 7/16/2026 8:51 AM, Dong, Zhanjun wrote:
> diff --git a/drivers/gpu/drm/xe/xe_guc_log.c b/drivers/gpu/drm/xe/xe_guc_log.c
> index 538d4df0f7aa..d0325c4f7b86 100644
> --- a/drivers/gpu/drm/xe/xe_guc_log.c
> +++ b/drivers/gpu/drm/xe/xe_guc_log.c
> @@ -225,16 +228,149 @@ struct xe_guc_log_snapshot *xe_guc_log_snapshot_capture(struct xe_guc_log *log,
>  	return snapshot;
>  }
>  
> +#if IS_ENABLED(CONFIG_DRM_XE_COMPRESS_DUMP)
> +static void xe_guc_print_blob_compressed(struct xe_gt *gt, struct drm_printer *p,
> +					 const char *length_label, const char *data_label,
> +					 void **chunks, int num_chunks,
> +					 size_t chunk_size, size_t total_size)
> +{
> +	zstd_parameters params;
> +	zstd_cstream *cstream;
> +	zstd_out_buffer outbuf;
> +	size_t wksp_size, dst_size;
> +	size_t remain, ret;
> +	void *wksp = NULL;
> +	char *dst = NULL;
> +	int i;
> +
> +	/*
> +	 * Pass 0 as estimated_src_size to use zstd level-3 defaults
> +	 * (windowLog=18, 256KB window). Passing the full total_size would
> +	 * cause zstd to inflate windowLog proportionally (e.g. windowLog=24
> +	 * for a 19MB log), making the workspace tens of MB.  With 0, the
> +	 * workspace stays ~1.5MB, well within kmalloc limits.
> +	 */
> +	params = zstd_get_params(3, 0);
> +
> +	wksp_size = zstd_cstream_workspace_bound(&params.cParams);
> +	wksp = kvzalloc(wksp_size, GFP_KERNEL);
> +	if (!wksp)
> +		goto err;
> +
> +	dst_size = zstd_compress_bound(total_size);
> +	dst = kvzalloc(dst_size, GFP_KERNEL);
> +	if (!dst)> +		goto err;
> +
> +	cstream = zstd_init_cstream(&params, 0, wksp, wksp_size);
> +	if (!cstream) {
> +		xe_gt_err(gt, "failed to init zstd cstream\n");
> +		goto err;
> +	}
> +
> +	outbuf.dst = dst;
> +	outbuf.size = dst_size;
> +	outbuf.pos = 0;
> +
> +	remain = total_size;
> +	for (i = 0; i < num_chunks && remain; i++) {
> +		size_t size = min(chunk_size, remain);
> +		zstd_in_buffer inbuf = { .src = chunks[i], .size = size, .pos = 0 };
> +
> +		while (inbuf.pos < inbuf.size) {
> +			ret = zstd_compress_stream(cstream, &outbuf, &inbuf);
> +			if (ZSTD_isError(ret)) {
> +				xe_gt_err(gt, "zstd_compress_stream failed: %s\n",
> +					  ZSTD_getErrorName(ret));
> +				goto err;
> +			}
> +		}
> +		remain -= size;
> +	}
> +
> +	do {
> +		ret = zstd_end_stream(cstream, &outbuf);
> +		if (ZSTD_isError(ret)) {
> +			xe_gt_err(gt, "zstd_end_stream failed: %s\n",
> +				  ZSTD_getErrorName(ret));
> +			goto err;
> +		}
> +	} while (ret > 0 && outbuf.pos < outbuf.size);
> +
> +	drm_printf(p, "%s.length: 0x%zx -> 0x%zx Algo: ZSTD\n",
> +		   length_label, total_size, outbuf.pos);
> +	xe_print_blob_ascii85(p, data_label, '\n', dst, 0,
> +			      DIV_ROUND_UP(outbuf.pos, sizeof(u32)) * sizeof(u32));
> +	goto out;
> +
> +err:
> +	drm_printf(p, "%s.length: 0x%zx Algo: ERROR (compression failed)\n",
> +		   length_label, total_size);
> +out:
> +	kvfree(dst);> +	kvfree(wksp);

Possible free of unallocated pointer? I don't think kvfree checks for null.

Maybe add checks before free. Or implement full error unroll via gotos.

	if (dst)
		kvfree(dst);
	if (wksp)
		kvfree(wksp);

> +}
> +#endif
> +




>  /**
> - * xe_guc_log_snapshot_print - dump a previously saved copy of the GuC log to some useful location
> - * @snapshot: a snapshot of the GuC log
> - * @p: the printer object to output to
> + * xe_guc_print_blob - Print binary data (compressed or uncompressed) as ascii85
> + * @gt: GT structure for error reporting
> + * @p: drm_printer for output
> + * @length_label: label prefix for the length/metadata line (e.g. "[LOG]" or "[CTB]")
> + * @data_label: label for the ascii85 blob (e.g. "[LOG].data" or "[CTB].data")
> + * @chunks: array of pointers to source data chunks
> + * @num_chunks: number of elements in @chunks
> + * @chunk_size: nominal size of each chunk; the last chunk may hold fewer valid bytes
> + * @total_size: total uncompressed byte count across all chunks
> + *
> + * If CONFIG_DRM_XE_COMPRESS_DUMP is enabled, compresses @total_size bytes using
> + * zstd level-3 streaming compression and prints the result via @p using ascii85
> + * encoding. Otherwise, directly prints the uncompressed data.
> + * On failure the function returns without printing the data blob.
>   */
> -void xe_guc_log_snapshot_print(struct xe_guc_log_snapshot *snapshot, struct drm_printer *p)
> +void xe_guc_print_blob(struct xe_gt *gt __maybe_unused, struct drm_printer *p,
> +		       const char *length_label, const char *data_label,
> +		       void **chunks, int num_chunks,
> +		       size_t chunk_size, size_t total_size)
>  {
> +#if IS_ENABLED(CONFIG_DRM_XE_COMPRESS_DUMP)
> +	xe_guc_print_blob_compressed(gt, p, length_label, data_label,
> +				     chunks, num_chunks, chunk_size, total_size);
> +#else
> +	/* Compression disabled, output uncompressed data directly */

Minor nit. Above comment line seems unneeded with funciton description already
covering the topic.
>  	size_t remain;
>  	int i;
>  
> +	drm_printf(p, "%s.length: 0x%zx Algo: RAW\n", length_label, total_size);
> +
> +	/*
> +	 * Print each chunk directly without merging into a single buffer.
> +	 * xe_print_blob_ascii85() supports multiple calls - use suffix=0
> +	 * for all but the last chunk to omit the newline between chunks.
> +	 */
> +	remain = total_size;
> +	for (i = 0; i < num_chunks && remain; i++) {
> +		size_t size = min(chunk_size, remain);
> +		const char *prefix = i ? NULL : data_label;
> +		/* Add suffix only on the last chunk */
> +		char suffix = (remain == size) ? '\n' : 0;
> +
> +		xe_print_blob_ascii85(p, prefix, suffix, chunks[i], 0,
> +				      DIV_ROUND_UP(size, sizeof(u32)) * sizeof(u32));
> +		remain -= size;
> +	}
> +#endif
> +}




> @@ -248,16 +384,9 @@ void xe_guc_log_snapshot_print(struct xe_guc_log_snapshot *snapshot, struct drm_
>  	drm_printf(p, "GuC timestamp: 0x%08llX [%llu]\n", snapshot->stamp, snapshot->stamp);
>  	drm_printf(p, "Log level: %u\n", snapshot->level);
>  
> -	drm_printf(p, "[LOG].length: 0x%zx\n", snapshot->size);
> -	remain = snapshot->size;
> -	for (i = 0; i < snapshot->num_chunks; i++) {
> -		size_t size = min(GUC_LOG_CHUNK_SIZE, remain);
> -		const char *prefix = i ? NULL : "[LOG].data";
> -		char suffix = i == snapshot->num_chunks - 1 ? '\n' : 0;
> -
> -		xe_print_blob_ascii85(p, prefix, suffix, snapshot->copy[i], 0, size);
> -		remain -= size;
> -	}

Variable remain may now unused with this block removed.

> +	xe_guc_print_blob(gt, p, "[LOG]", "[LOG].data",
> +			  snapshot->copy, snapshot->num_chunks,
> +			  GUC_LOG_CHUNK_SIZE, snapshot->size);
>  }
>  
>  static inline void lfd_output_binary(struct drm_printer *p, char *buf, int buf_size)