1 files changed, 99 insertions, 45 deletions

diff --git a/drivers/gpu/drm/xe/xe_devcoredump.c b/drivers/gpu/drm/xe/xe_devcoredump.c
index f8947e7e917e..39fe485d2085 100644
--- a/drivers/gpu/drm/xe/xe_devcoredump.c
+++ b/drivers/gpu/drm/xe/xe_devcoredump.c
@@ -30,30 +30,39 @@
 /**
  * DOC: Xe device coredump
  *
- * Devices overview:
  * Xe uses dev_coredump infrastructure for exposing the crash errors in a
- * standardized way.
- * devcoredump exposes a temporary device under /sys/class/devcoredump/
- * which is linked with our card device directly.
- * The core dump can be accessed either from
- * /sys/class/drm/card<n>/device/devcoredump/ or from
- * /sys/class/devcoredump/devcd<m> where
- * /sys/class/devcoredump/devcd<m>/failing_device is a link to
- * /sys/class/drm/card<n>/device/.
+ * standardized way. Once a crash occurs, devcoredump exposes a temporary
+ * node under ``/sys/class/devcoredump/devcd<m>/``. The same node is also
+ * accessible in ``/sys/class/drm/card<n>/device/devcoredump/``. The
+ * ``failing_device`` symlink points to the device that crashed and created the
+ * coredump.
  *
- * Snapshot at hang:
- * The 'data' file is printed with a drm_printer pointer at devcoredump read
- * time. For this reason, we need to take snapshots from when the hang has
- * happened, and not only when the user is reading the file. Otherwise the
- * information is outdated since the resets might have happened in between.
+ * The following characteristics are observed by xe when creating a device
+ * coredump:
  *
- * 'First' failure snapshot:
- * In general, the first hang is the most critical one since the following hangs
- * can be a consequence of the initial hang. For this reason we only take the
- * snapshot of the 'first' failure and ignore subsequent calls of this function,
- * at least while the coredump device is alive. Dev_coredump has a delayed work
- * queue that will eventually delete the device and free all the dump
- * information.
+ * **Snapshot at hang**:
+ *   The 'data' file contains a snapshot of the HW and driver states at the time
+ *   the hang happened. Due to the driver recovering from resets/crashes, it may
+ *   not correspond to the state of the system when the file is read by
+ *   userspace.
+ *
+ * **Coredump release**:
+ *   After a coredump is generated, it stays in kernel memory until released by
+ *   userspace by writing anything to it, or after an internal timer expires. The
+ *   exact timeout may vary and should not be relied upon. Example to release
+ *   a coredump:
+ *
+ *   .. code-block:: shell
+ *
+ *	$ > /sys/class/drm/card0/device/devcoredump/data
+ *
+ * **First failure only**:
+ *   In general, the first hang is the most critical one since the following
+ *   hangs can be a consequence of the initial hang. For this reason a snapshot
+ *   is taken only for the first failure. Until the devcoredump is released by
+ *   userspace or kernel, all subsequent hangs do not override the snapshot nor
+ *   create new ones. Devcoredump has a delayed work queue that will eventually
+ *   delete the file node and free all the dump information.
  */
 
 #ifdef CONFIG_DEV_COREDUMP
@@ -91,6 +100,7 @@ static ssize_t __xe_devcoredump_read(char *buffer, size_t count,
 	p = drm_coredump_printer(&iter);
 
 	drm_puts(&p, "**** Xe Device Coredump ****\n");
+	drm_printf(&p, "Reason: %s\n", ss->reason);
 	drm_puts(&p, "kernel: " UTS_RELEASE "\n");
 	drm_puts(&p, "module: " KBUILD_MODNAME "\n");
 
@@ -98,7 +108,7 @@ static ssize_t __xe_devcoredump_read(char *buffer, size_t count,
 	drm_printf(&p, "Snapshot time: %lld.%09ld\n", ts.tv_sec, ts.tv_nsec);
 	ts = ktime_to_timespec64(ss->boot_time);
 	drm_printf(&p, "Uptime: %lld.%09ld\n", ts.tv_sec, ts.tv_nsec);
-	drm_printf(&p, "Process: %s\n", ss->process_name);
+	drm_printf(&p, "Process: %s [%d]\n", ss->process_name, ss->pid);
 	xe_device_snapshot_print(xe, &p);
 
 	drm_printf(&p, "\n**** GT #%d ****\n", ss->gt->info.id);
@@ -130,6 +140,9 @@ static void xe_devcoredump_snapshot_free(struct xe_devcoredump_snapshot *ss)
 {
 	int i;
 
+	kfree(ss->reason);
+	ss->reason = NULL;
+
 	xe_guc_log_snapshot_free(ss->guc.log);
 	ss->guc.log = NULL;
 
@@ -170,16 +183,24 @@ static ssize_t xe_devcoredump_read(char *buffer, loff_t offset,
 	/* Ensure delayed work is captured before continuing */
 	flush_work(&ss->work);
 
-	if (!ss->read.buffer)
+	mutex_lock(&coredump->lock);
+
+	if (!ss->read.buffer) {
+		mutex_unlock(&coredump->lock);
 		return -ENODEV;
+	}
 
-	if (offset >= ss->read.size)
+	if (offset >= ss->read.size) {
+		mutex_unlock(&coredump->lock);
 		return 0;
+	}
 
 	byte_copied = count < ss->read.size - offset ? count :
 		ss->read.size - offset;
 	memcpy(buffer, ss->read.buffer + offset, byte_copied);
 
+	mutex_unlock(&coredump->lock);
+
 	return byte_copied;
 }
 
@@ -193,15 +214,18 @@ static void xe_devcoredump_free(void *data)
 
 	cancel_work_sync(&coredump->snapshot.work);
 
+	mutex_lock(&coredump->lock);
+
 	xe_devcoredump_snapshot_free(&coredump->snapshot);
 	kvfree(coredump->snapshot.read.buffer);
 
 	/* To prevent stale data on next snapshot, clear everything */
 	memset(&coredump->snapshot, 0, sizeof(coredump->snapshot));
 	coredump->captured = false;
-	coredump->job = NULL;
 	drm_info(&coredump_to_xe(coredump)->drm,
 		 "Xe device coredump has been deleted.\n");
+
+	mutex_unlock(&coredump->lock);
 }
 
 static void xe_devcoredump_deferred_snap_work(struct work_struct *work)
@@ -244,10 +268,10 @@ static void xe_devcoredump_deferred_snap_work(struct work_struct *work)
 }
 
 static void devcoredump_snapshot(struct xe_devcoredump *coredump,
+				 struct xe_exec_queue *q,
 				 struct xe_sched_job *job)
 {
 	struct xe_devcoredump_snapshot *ss = &coredump->snapshot;
-	struct xe_exec_queue *q = job->q;
 	struct xe_guc *guc = exec_queue_to_guc(q);
 	u32 adj_logical_mask = q->logical_mask;
 	u32 width_mask = (0x1 << q->width) - 1;
@@ -260,12 +284,14 @@ static void devcoredump_snapshot(struct xe_devcoredump *coredump,
 	ss->snapshot_time = ktime_get_real();
 	ss->boot_time = ktime_get_boottime();
 
-	if (q->vm && q->vm->xef)
+	if (q->vm && q->vm->xef) {
 		process_name = q->vm->xef->process_name;
+		ss->pid = q->vm->xef->pid;
+	}
+
 	strscpy(ss->process_name, process_name);
 
 	ss->gt = q->gt;
-	coredump->job = job;
 	INIT_WORK(&ss->work, xe_devcoredump_deferred_snap_work);
 
 	cookie = dma_fence_begin_signalling();
@@ -284,10 +310,11 @@ static void devcoredump_snapshot(struct xe_devcoredump *coredump,
 	ss->guc.log = xe_guc_log_snapshot_capture(&guc->log, true);
 	ss->guc.ct = xe_guc_ct_snapshot_capture(&guc->ct);
 	ss->ge = xe_guc_exec_queue_snapshot_capture(q);
-	ss->job = xe_sched_job_snapshot_capture(job);
+	if (job)
+		ss->job = xe_sched_job_snapshot_capture(job);
 	ss->vm = xe_vm_snapshot_capture(q->vm);
 
-	xe_engine_snapshot_capture_for_job(job);
+	xe_engine_snapshot_capture_for_queue(q);
 
 	queue_work(system_unbound_wq, &ss->work);
 
@@ -297,28 +324,42 @@ static void devcoredump_snapshot(struct xe_devcoredump *coredump,
 
 /**
  * xe_devcoredump - Take the required snapshots and initialize coredump device.
+ * @q: The faulty xe_exec_queue, where the issue was detected.
  * @job: The faulty xe_sched_job, where the issue was detected.
+ * @fmt: Printf format + args to describe the reason for the core dump
  *
  * This function should be called at the crash time within the serialized
  * gt_reset. It is skipped if we still have the core dump device available
  * with the information of the 'first' snapshot.
  */
-void xe_devcoredump(struct xe_sched_job *job)
+__printf(3, 4)
+void xe_devcoredump(struct xe_exec_queue *q, struct xe_sched_job *job, const char *fmt, ...)
 {
-	struct xe_device *xe = gt_to_xe(job->q->gt);
+	struct xe_device *xe = gt_to_xe(q->gt);
 	struct xe_devcoredump *coredump = &xe->devcoredump;
+	va_list varg;
+
+	mutex_lock(&coredump->lock);
 
 	if (coredump->captured) {
 		drm_dbg(&xe->drm, "Multiple hangs are occurring, but only the first snapshot was taken\n");
+		mutex_unlock(&coredump->lock);
 		return;
 	}
 
 	coredump->captured = true;
-	devcoredump_snapshot(coredump, job);
+
+	va_start(varg, fmt);
+	coredump->snapshot.reason = kvasprintf(GFP_ATOMIC, fmt, varg);
+	va_end(varg);
+
+	devcoredump_snapshot(coredump, q, job);
 
 	drm_info(&xe->drm, "Xe device coredump has been created\n");
 	drm_info(&xe->drm, "Check your /sys/class/drm/card%d/device/devcoredump/data\n",
 		 xe->drm.primary->index);
+
+	mutex_unlock(&coredump->lock);
 }
 
 static void xe_driver_devcoredump_fini(void *arg)
@@ -330,6 +371,18 @@ static void xe_driver_devcoredump_fini(void *arg)
 
 int xe_devcoredump_init(struct xe_device *xe)
 {
+	int err;
+
+	err = drmm_mutex_init(&xe->drm, &xe->devcoredump.lock);
+	if (err)
+		return err;
+
+	if (IS_ENABLED(CONFIG_LOCKDEP)) {
+		fs_reclaim_acquire(GFP_KERNEL);
+		might_lock(&xe->devcoredump.lock);
+		fs_reclaim_release(GFP_KERNEL);
+	}
+
 	return devm_add_action_or_reset(xe->drm.dev, xe_driver_devcoredump_fini, &xe->drm);
 }
 
@@ -338,25 +391,25 @@ int xe_devcoredump_init(struct xe_device *xe)
 /**
  * xe_print_blob_ascii85 - print a BLOB to some useful location in ASCII85
  *
- * The output is split to multiple lines because some print targets, e.g. dmesg
- * cannot handle arbitrarily long lines. Note also that printing to dmesg in
- * piece-meal fashion is not possible, each separate call to drm_puts() has a
- * line-feed automatically added! Therefore, the entire output line must be
- * constructed in a local buffer first, then printed in one atomic output call.
+ * The output is split into multiple calls to drm_puts() because some print
+ * targets, e.g. dmesg, cannot handle arbitrarily long lines. These targets may
+ * add newlines, as is the case with dmesg: each drm_puts() call creates a
+ * separate line.
  *
  * There is also a scheduler yield call to prevent the 'task has been stuck for
  * 120s' kernel hang check feature from firing when printing to a slow target
  * such as dmesg over a serial port.
  *
- * TODO: Add compression prior to the ASCII85 encoding to shrink huge buffers down.
- *
  * @p: the printer object to output to
  * @prefix: optional prefix to add to output string
+ * @suffix: optional suffix to add at the end. 0 disables it and is
+ *          not added to the output, which is useful when using multiple calls
+ *          to dump data to @p
  * @blob: the Binary Large OBject to dump out
  * @offset: offset in bytes to skip from the front of the BLOB, must be a multiple of sizeof(u32)
  * @size: the size in bytes of the BLOB, must be a multiple of sizeof(u32)
  */
-void xe_print_blob_ascii85(struct drm_printer *p, const char *prefix,
+void xe_print_blob_ascii85(struct drm_printer *p, const char *prefix, char suffix,
 			   const void *blob, size_t offset, size_t size)
 {
 	const u32 *blob32 = (const u32 *)blob;
@@ -364,7 +417,8 @@ void xe_print_blob_ascii85(struct drm_printer *p, const char *prefix,
 	size_t line_pos = 0;
 
 #define DMESG_MAX_LINE_LEN	800
-#define MIN_SPACE		(ASCII85_BUFSZ + 2)		/* 85 + "\n\0" */
+	/* Always leave space for the suffix char and the \0 */
+#define MIN_SPACE		(ASCII85_BUFSZ + 2)	/* 85 + "<suffix>\0" */
 
 	if (size & 3)
 		drm_printf(p, "Size not word aligned: %zu", size);
@@ -396,7 +450,6 @@ void xe_print_blob_ascii85(struct drm_printer *p, const char *prefix,
 		line_pos += strlen(line_buff + line_pos);
 
 		if ((line_pos + MIN_SPACE) >= DMESG_MAX_LINE_LEN) {
-			line_buff[line_pos++] = '\n';
 			line_buff[line_pos++] = 0;
 
 			drm_puts(p, line_buff);
@@ -408,10 +461,11 @@ void xe_print_blob_ascii85(struct drm_printer *p, const char *prefix,
 		}
 	}
 
+	if (suffix)
+		line_buff[line_pos++] = suffix;
+
 	if (line_pos) {
-		line_buff[line_pos++] = '\n';
 		line_buff[line_pos++] = 0;
-
 		drm_puts(p, line_buff);
 	}