[PATCH v7 2/2] drm/xe/guc: Compress GuC log and CTB dump with zstd

[Zhanjun Dong <zhanjun.dong@intel.com>]

With the default settings, the GuC log is several megabytes in size.
Printing the entire log is time-consuming. In debugging scenarios,
printing the GuC log to dmesg while forwarding the dmesg output to a
serial console can take several minutes. It can also exhaust the storage
allocated to CI logs. Follow i915's approach and compress the GuC dump
data to address these issues.

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>
---
 drivers/gpu/drm/xe/Kconfig          |  15 +++
 drivers/gpu/drm/xe/xe_devcoredump.c |   4 +-
 drivers/gpu/drm/xe/xe_guc_ct.c      |  19 ++--
 drivers/gpu/drm/xe/xe_guc_ct.h      |   4 +-
 drivers/gpu/drm/xe/xe_guc_log.c     | 161 +++++++++++++++++++++++++---
 drivers/gpu/drm/xe/xe_guc_log.h     |   9 +-
 6 files changed, 183 insertions(+), 29 deletions(-)

diff --git a/drivers/gpu/drm/xe/Kconfig b/drivers/gpu/drm/xe/Kconfig
index 4d7dcaff2b91..18a682a44b31 100644
--- a/drivers/gpu/drm/xe/Kconfig
+++ b/drivers/gpu/drm/xe/Kconfig
@@ -33,6 +33,7 @@ config DRM_XE
 	select ACPI_WMI if X86 && ACPI
 	select SYNC_FILE
 	select CRC32
+	select ZSTD_COMPRESS if DRM_XE_COMPRESS_DUMP
 	select SND_HDA_I915 if SND_HDA_CORE
 	select CEC_CORE if CEC_NOTIFIER
 	select VMAP_PFN
@@ -101,6 +102,20 @@ 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
+	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 5f2b90b18f97..27473c25aad2 100644
--- a/drivers/gpu/drm/xe/xe_devcoredump.c
+++ b/drivers/gpu/drm/xe/xe_devcoredump.c
@@ -115,9 +115,9 @@ 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 fe70c0fd85c5..19314184798c 100644
--- a/drivers/gpu/drm/xe/xe_guc_ct.c
+++ b/drivers/gpu/drm/xe/xe_guc_ct.c
@@ -2135,11 +2135,12 @@ 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;
@@ -2153,11 +2154,10 @@ 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");
 	}
@@ -2191,9 +2191,10 @@ 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);
 }
 
@@ -2291,10 +2292,10 @@ 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 767365a33dee..2005d1a0cd6c 100644
--- a/drivers/gpu/drm/xe/xe_guc_ct.h
+++ b/drivers/gpu/drm/xe/xe_guc_ct.h
@@ -10,6 +10,7 @@
 
 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);
@@ -24,7 +25,8 @@ 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 538d4df0f7aa..aaeb0f76af30 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>
@@ -225,16 +228,148 @@ 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);
+}
+#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;
@@ -248,16 +383,9 @@ 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)
@@ -598,12 +726,13 @@ 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
-- 
2.34.1