[PATCH] drm/xe: Allow to trigger GT resets using debugfs writes

[Michal Wajdeczko]

Today we allow to trigger GT resest by reading dedicated debugfs
files "force_reset" and "force_reset_sync" that we are exposing
using drm_info_list[] and drm_debugfs_create_files().

To avoid triggering potentially disruptive actions during otherwise
"safe" read operations, expose those two attributes using debugfs
function where we can specify file permissions and provide custom
"write" handler to trigger the GT resets also from there.

This step would allow us to drop triggering GT resets during read
operations, which we leave just to give users more time to switch.

Signed-off-by: Michal Wajdeczko <michal.wajdeczko at intel.com>
Cc: Lucas De Marchi <lucas.demarchi at intel.com>
Cc: Rodrigo Vivi <rodrigo.vivi at intel.com>
---
 drivers/gpu/drm/xe/xe_gt_debugfs.c | 96 +++++++++++++++++++++++-------
 1 file changed, 76 insertions(+), 20 deletions(-)

diff --git a/drivers/gpu/drm/xe/xe_gt_debugfs.c b/drivers/gpu/drm/xe/xe_gt_debugfs.c
index 119a55bb7580..848618acdca8 100644
--- a/drivers/gpu/drm/xe/xe_gt_debugfs.c
+++ b/drivers/gpu/drm/xe/xe_gt_debugfs.c
@@ -122,24 +122,6 @@ static int powergate_info(struct xe_gt *gt, struct drm_printer *p)
 	return ret;
 }
 
-static int force_reset(struct xe_gt *gt, struct drm_printer *p)
-{
-	xe_pm_runtime_get(gt_to_xe(gt));
-	xe_gt_reset_async(gt);
-	xe_pm_runtime_put(gt_to_xe(gt));
-
-	return 0;
-}
-
-static int force_reset_sync(struct xe_gt *gt, struct drm_printer *p)
-{
-	xe_pm_runtime_get(gt_to_xe(gt));
-	xe_gt_reset(gt);
-	xe_pm_runtime_put(gt_to_xe(gt));
-
-	return 0;
-}
-
 static int sa_info(struct xe_gt *gt, struct drm_printer *p)
 {
 	struct xe_tile *tile = gt_to_tile(gt);
@@ -306,8 +288,6 @@ static int hwconfig(struct xe_gt *gt, struct drm_printer *p)
  * - without access to the PF specific data
  */
 static const struct drm_info_list vf_safe_debugfs_list[] = {
-	{"force_reset", .show = xe_gt_debugfs_simple_show, .data = force_reset},
-	{"force_reset_sync", .show = xe_gt_debugfs_simple_show, .data = force_reset_sync},
 	{"sa_info", .show = xe_gt_debugfs_simple_show, .data = sa_info},
 	{"topology", .show = xe_gt_debugfs_simple_show, .data = topology},
 	{"ggtt", .show = xe_gt_debugfs_simple_show, .data = ggtt},
@@ -332,6 +312,78 @@ static const struct drm_info_list pf_only_debugfs_list[] = {
 	{"steering", .show = xe_gt_debugfs_simple_show, .data = steering},
 };
 
+static ssize_t write_to_gt_call(const char __user *userbuf, size_t count, loff_t *ppos,
+				void (*call)(struct xe_gt *), struct xe_gt *gt)
+{
+	bool yes;
+	int ret;
+
+	if (*ppos)
+		return -EINVAL;
+	ret = kstrtobool_from_user(userbuf, count, &yes);
+	if (ret < 0)
+		return ret;
+	if (yes)
+		call(gt);
+	return count;
+}
+
+static void force_reset(struct xe_gt *gt)
+{
+	struct xe_device *xe = gt_to_xe(gt);
+
+	xe_pm_runtime_get(xe);
+	xe_gt_reset_async(gt);
+	xe_pm_runtime_put(xe);
+}
+
+static ssize_t force_reset_write(struct file *file,
+				 const char __user *userbuf,
+				 size_t count, loff_t *ppos)
+{
+	struct seq_file *s = file->private_data;
+	struct xe_gt *gt = s->private;
+
+	return write_to_gt_call(userbuf, count, ppos, force_reset, gt);
+}
+
+static int force_reset_show(struct seq_file *s, void *unused)
+{
+	struct xe_gt *gt = s->private;
+
+	force_reset(gt); /* to be deprecated! */
+	return 0;
+}
+DEFINE_SHOW_STORE_ATTRIBUTE(force_reset);
+
+static void force_reset_sync(struct xe_gt *gt)
+{
+	struct xe_device *xe = gt_to_xe(gt);
+
+	xe_pm_runtime_get(xe);
+	xe_gt_reset(gt);
+	xe_pm_runtime_put(xe);
+}
+
+static ssize_t force_reset_sync_write(struct file *file,
+				      const char __user *userbuf,
+				      size_t count, loff_t *ppos)
+{
+	struct seq_file *s = file->private_data;
+	struct xe_gt *gt = s->private;
+
+	return write_to_gt_call(userbuf, count, ppos, force_reset_sync, gt);
+}
+
+static int force_reset_sync_show(struct seq_file *s, void *unused)
+{
+	struct xe_gt *gt = s->private;
+
+	force_reset_sync(gt); /* to be deprecated! */
+	return 0;
+}
+DEFINE_SHOW_STORE_ATTRIBUTE(force_reset_sync);
+
 void xe_gt_debugfs_register(struct xe_gt *gt)
 {
 	struct xe_device *xe = gt_to_xe(gt);
@@ -355,6 +407,10 @@ void xe_gt_debugfs_register(struct xe_gt *gt)
 	 */
 	root->d_inode->i_private = gt;
 
+	/* VF safe */
+	debugfs_create_file("force_reset", 0600, root, gt, &force_reset_fops);
+	debugfs_create_file("force_reset_sync", 0600, root, gt, &force_reset_sync_fops);
+
 	drm_debugfs_create_files(vf_safe_debugfs_list,
 				 ARRAY_SIZE(vf_safe_debugfs_list),
 				 root, minor);
-- 
2.47.1