drm/xe/guc: Compress GuC log and CTB dump with zstd

With default settings, GuC log is 8MB in size and
dumping the log is time-consuming. In debugging scenarios,
dump-to-dmesg suffers truncation loss because CI's size limit is 2MB.
Additionally, if also forwarded to serial console, it takes several
minutes. In use-case of continuous error+log collection over extended
period, we pressure CI's allocated storage. Thus, compress the
GuC log data dump to address these issues and multiply any benefits
from a future upgrade in CI's size limits.

Replace the raw ascii85 dumps of GuC log snapshots with a
zstd-compressed ascii85 stream and reuse the same helper for CTB
snapshot output.

Use zstd streaming with the default compression level of 3 and an
estimated source size of 0 so the compression workspace stays bounded
even for multi-megabyte logs.

Add a new Kconfig option DRM_XE_COMPRESS_DUMP to control whether
GuC log and CTB dumps are compressed with ZSTD. This allows users to
choose between reduced dump sizes and lower memory usage.

Signed-off-by: Zhanjun Dong <zhanjun.dong@intel.com>
Signed-off-by: Alan Previn <alan.previn.teres.alexis@intel.com>
Acked-by: José Roberto de Souza <jose.souza@intel.com>
Acked-by: Rodrigo Vivi <rodrigo.vivi@intel.com>
Reviewed-by: Julia Filipchuk <julia.filipchuk@intel.com>
Link: https://patch.msgid.link/20261013222846.308259-7-alan.previn.teres.alexis@intel.com
Signed-off-by: Rodrigo Vivi <rodrigo.vivi@intel.com>

6 files changed, 190 insertions, 29 deletions

diff --git a/drivers/gpu/drm/xe/Kconfig b/drivers/gpu/drm/xe/Kconfig
index 4d7dcaff2b91..0d87251c5d7c 100644
--- a/drivers/gpu/drm/xe/Kconfig
+++ b/drivers/gpu/drm/xe/Kconfig
@@ -101,6 +101,21 @@ config DRM_XE_PAGEMAP
 
 	  If in doubt say "Y".
 
+config DRM_XE_COMPRESS_DUMP
+	bool "Enable ZSTD compression for error dumps"
+	depends on DRM_XE
+	default y
+	select ZSTD_COMPRESS
+	help
+	  Enable this option to compress GuC log and CTB dumps with ZSTD
+	  compression. This can significantly reduce the size of error dumps
+	  but requires additional memory for compression workspace.
+
+	  Disable this option if you want to save memory or prefer uncompressed
+	  error dumps for debugging.
+
+	  If in doubt say "Y".
+
 config DRM_XE_FORCE_PROBE
 	string "Force probe xe for selected Intel hardware IDs"
 	depends on DRM_XE
diff --git a/drivers/gpu/drm/xe/xe_devcoredump.c b/drivers/gpu/drm/xe/xe_devcoredump.c
index ab681b148869..133cbe196d66 100644
--- a/drivers/gpu/drm/xe/xe_devcoredump.c
+++ b/drivers/gpu/drm/xe/xe_devcoredump.c
@@ -110,9 +110,9 @@ static ssize_t __xe_devcoredump_read(char *buffer, ssize_t count,
 	drm_printf(&p, "\tTile: %d\n", ss->gt->tile->id);
 
 	drm_puts(&p, "\n**** GuC Log ****\n");
-	xe_guc_log_snapshot_print(ss->guc.log, &p);
+	xe_guc_log_snapshot_print(ss->guc.log, &p, ss->gt);
 	drm_puts(&p, "\n**** GuC CT ****\n");
-	xe_guc_ct_snapshot_print(ss->guc.ct, &p);
+	xe_guc_ct_snapshot_print(ss->guc.ct, &p, ss->gt);
 
 	drm_puts(&p, "\n**** Contexts ****\n");
 	xe_guc_exec_queue_snapshot_print(ss->ge, &p);
diff --git a/drivers/gpu/drm/xe/xe_guc_ct.c b/drivers/gpu/drm/xe/xe_guc_ct.c
index da5ce97484b8..0d2464c72277 100644
--- a/drivers/gpu/drm/xe/xe_guc_ct.c
+++ b/drivers/gpu/drm/xe/xe_guc_ct.c
@@ -2201,11 +2201,12 @@ struct xe_guc_ct_snapshot *xe_guc_ct_snapshot_capture(struct xe_guc_ct *ct)
  * xe_guc_ct_snapshot_print - Print out a given GuC CT snapshot.
  * @snapshot: GuC CT snapshot object.
  * @p: drm_printer where it will be printed out.
+ * @gt: GT structure for error reporting
  *
  * This function prints out a given GuC CT snapshot object.
  */
 void xe_guc_ct_snapshot_print(struct xe_guc_ct_snapshot *snapshot,
-			      struct drm_printer *p)
+			      struct drm_printer *p, struct xe_gt *gt)
 {
 	if (!snapshot)
 		return;
@@ -2219,11 +2220,10 @@ void xe_guc_ct_snapshot_print(struct xe_guc_ct_snapshot *snapshot,
 		drm_printf(p, "\tg2h outstanding: %d\n",
 			   snapshot->g2h_outstanding);
 
-		if (snapshot->ctb) {
-			drm_printf(p, "[CTB].length: 0x%zx\n", snapshot->ctb_size);
-			xe_print_blob_ascii85(p, "[CTB].data", '\n',
-					      snapshot->ctb, 0, snapshot->ctb_size);
-		}
+		if (snapshot->ctb)
+			xe_guc_print_blob(gt, p, "[CTB]", "[CTB].data",
+					  &snapshot->ctb, 1,
+					  snapshot->ctb_size, snapshot->ctb_size);
 	} else {
 		drm_puts(p, "CT disabled\n");
 	}
@@ -2257,9 +2257,10 @@ void xe_guc_ct_snapshot_free(struct xe_guc_ct_snapshot *snapshot)
 void xe_guc_ct_print(struct xe_guc_ct *ct, struct drm_printer *p, bool want_ctb)
 {
 	struct xe_guc_ct_snapshot *snapshot;
+	struct xe_gt *gt = ct_to_gt(ct);
 
 	snapshot = guc_ct_snapshot_capture(ct, false, want_ctb);
-	xe_guc_ct_snapshot_print(snapshot, p);
+	xe_guc_ct_snapshot_print(snapshot, p, gt);
 	xe_guc_ct_snapshot_free(snapshot);
 }
 
@@ -2357,10 +2358,10 @@ static void ct_dead_print(struct xe_dead_ct *dead)
 	drm_printf(&lp, "\tTile: %d\n", gt->tile->id);
 
 	drm_puts(&lp, "**** GuC Log ****\n");
-	xe_guc_log_snapshot_print(dead->snapshot_log, &lp);
+	xe_guc_log_snapshot_print(dead->snapshot_log, &lp, gt);
 
 	drm_puts(&lp, "**** GuC CT ****\n");
-	xe_guc_ct_snapshot_print(dead->snapshot_ct, &lp);
+	xe_guc_ct_snapshot_print(dead->snapshot_ct, &lp, gt);
 
 	drm_puts(&lp, "Done.\n");
 }
diff --git a/drivers/gpu/drm/xe/xe_guc_ct.h b/drivers/gpu/drm/xe/xe_guc_ct.h
index e2a33249d65d..f3af15c95c75 100644
--- a/drivers/gpu/drm/xe/xe_guc_ct.h
+++ b/drivers/gpu/drm/xe/xe_guc_ct.h
@@ -12,6 +12,7 @@
 
 struct drm_printer;
 struct xe_device;
+struct xe_gt;
 
 int xe_guc_ct_init_noalloc(struct xe_guc_ct *ct);
 int xe_guc_ct_init(struct xe_guc_ct *ct);
@@ -26,7 +27,8 @@ void xe_guc_ct_flush_and_stop(struct xe_guc_ct *ct);
 void xe_guc_ct_fast_path(struct xe_guc_ct *ct);
 
 struct xe_guc_ct_snapshot *xe_guc_ct_snapshot_capture(struct xe_guc_ct *ct);
-void xe_guc_ct_snapshot_print(struct xe_guc_ct_snapshot *snapshot, struct drm_printer *p);
+void xe_guc_ct_snapshot_print(struct xe_guc_ct_snapshot *snapshot, struct drm_printer *p,
+			      struct xe_gt *gt);
 void xe_guc_ct_snapshot_free(struct xe_guc_ct_snapshot *snapshot);
 void xe_guc_ct_print(struct xe_guc_ct *ct, struct drm_printer *p, bool want_ctb);
 
diff --git a/drivers/gpu/drm/xe/xe_guc_log.c b/drivers/gpu/drm/xe/xe_guc_log.c
index 7d006268ce91..47adaf70d5bf 100644
--- a/drivers/gpu/drm/xe/xe_guc_log.c
+++ b/drivers/gpu/drm/xe/xe_guc_log.c
@@ -6,6 +6,9 @@
 #include "xe_guc_log.h"
 
 #include <linux/fault-inject.h>
+#if IS_ENABLED(CONFIG_DRM_XE_COMPRESS_DUMP)
+#include <linux/zstd.h>
+#endif
 
 #include <linux/utsname.h>
 #include <drm/drm_managed.h>
@@ -226,16 +229,155 @@ 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);
+	/*
+	 * zstd may only write dst_size bytes, but xe_print_blob_ascii85() reads
+	 * the blob a u32 at a time and so touches up to three bytes past the
+	 * last compressed byte. Round-up allocation to a u32 boundary rather than
+	 * rely on dst_size happening to be aligned. kvzalloc() leaves that
+	 * padding zeroed, which also keeps the encoded tail reproducible.
+	 */
+	dst = kvzalloc(round_up(dst_size, sizeof(u32)), 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);
+}
+#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
 	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
+}
+
+/**
+ * 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
+ * @gt: GT structure of the GuC log
+ */
+void xe_guc_log_snapshot_print(struct xe_guc_log_snapshot *snapshot, struct drm_printer *p,
+			       struct xe_gt *gt)
+{
 	if (!snapshot) {
 		drm_printf(p, "GuC log snapshot not allocated!\n");
 		return;
@@ -249,16 +391,9 @@ 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;
-	}
+	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)
@@ -599,12 +734,13 @@ void xe_guc_log_print_dmesg(struct xe_guc_log *log)
 void xe_guc_log_print(struct xe_guc_log *log, struct drm_printer *p)
 {
 	struct xe_guc_log_snapshot *snapshot;
+	struct xe_gt *gt = log_to_gt(log);
 
 	drm_printf(p, "**** GuC Log ****\n");
 
 	snapshot = xe_guc_log_snapshot_capture(log, false);
-	drm_printf(p, "CS reference clock: %u\n", log_to_gt(log)->info.reference_clock);
-	xe_guc_log_snapshot_print(snapshot, p);
+	drm_printf(p, "CS reference clock: %u\n", gt->info.reference_clock);
+	xe_guc_log_snapshot_print(snapshot, p, gt);
 	xe_guc_log_snapshot_free(snapshot);
 }
 
diff --git a/drivers/gpu/drm/xe/xe_guc_log.h b/drivers/gpu/drm/xe/xe_guc_log.h
index 4649a260755e..3e97647ee8b5 100644
--- a/drivers/gpu/drm/xe/xe_guc_log.h
+++ b/drivers/gpu/drm/xe/xe_guc_log.h
@@ -11,6 +11,7 @@
 
 struct drm_printer;
 struct xe_device;
+struct xe_gt;
 
 #if IS_ENABLED(CONFIG_DRM_XE_DEBUG_GUC)
 #define XE_GUC_LOG_EVENT_DATA_BUFFER_SIZE	SZ_16M
@@ -59,7 +60,13 @@ void xe_guc_log_print(struct xe_guc_log *log, struct drm_printer *p);
 void xe_guc_log_print_lfd(struct xe_guc_log *log, struct drm_printer *p);
 void xe_guc_log_print_dmesg(struct xe_guc_log *log);
 struct xe_guc_log_snapshot *xe_guc_log_snapshot_capture(struct xe_guc_log *log, bool atomic);
-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, 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);
+
+void xe_guc_log_snapshot_print(struct xe_guc_log_snapshot *snapshot, struct drm_printer *p,
+			       struct xe_gt *gt);
 void xe_guc_log_snapshot_free(struct xe_guc_log_snapshot *snapshot);
 
 static inline u32