drm/xe/configfs: Add mid context restore bb

Like done for post context restore, allow the user to add commands to
the middle of context restore, at the beginning of engine restore
commands.

Reviewed-by: Rodrigo Vivi <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Lucas De Marchi <[email protected]>

Author: lucasdemarchi

drivers/gpu/drm/xe/xe_configfs.c

@@ -126,13 +126,21 @@
  * not intended for normal execution and will taint the kernel with TAINT_TEST
  * when used.
  *
- * Currently this is implemented only for post context restore. Examples:
+ * Currently this is implemented only for post and mid context restore.
+ * Examples:
  *
- * #. Execute a LRI command to write 0xDEADBEEF to register 0x4f10::
+ * #. Execute a LRI command to write 0xDEADBEEF to register 0x4f10 after the
+ *    normal context restore::
  *
  *	# echo 'rcs cmd 11000001 4F100 DEADBEEF' \
  *		> /sys/kernel/config/xe/0000:03:00.0/ctx_restore_post_bb
  *
+ * #. Execute a LRI command to write 0xDEADBEEF to register 0x4f10 at the
+ *    beginning of the context restore::
+ *
+ *	# echo 'rcs cmd 11000001 4F100 DEADBEEF' \
+ *		> /sys/kernel/config/xe/0000:03:00.0/ctx_restore_mid_bb
+
  * #. Load certain values in a couple of registers (it can be used as a simpler
  *    alternative to the `cmd`) action::
  *
@@ -146,7 +154,7 @@
  *       When using multiple lines, make sure to use a command that is
  *       implemented with a single write syscall, like HEREDOC.
  *
- * This attribute can only be set before binding to the device.
+ * These attributes can only be set before binding to the device.
  *
  * Remove devices
  * ==============
@@ -168,6 +176,7 @@ struct xe_config_group_device {
 	struct xe_config_device {
 		u64 engines_allowed;
 		struct wa_bb ctx_restore_post_bb[XE_ENGINE_CLASS_MAX];
+		struct wa_bb ctx_restore_mid_bb[XE_ENGINE_CLASS_MAX];
 		bool survivability_mode;
 		bool enable_psmi;
 	} config;
@@ -467,6 +476,13 @@ static ssize_t wa_bb_show(struct xe_config_group_device *dev,
 	return p - data;
 }
 
+static ssize_t ctx_restore_mid_bb_show(struct config_item *item, char *page)
+{
+	struct xe_config_group_device *dev = to_xe_config_group_device(item);
+
+	return wa_bb_show(dev, dev->config.ctx_restore_mid_bb, page, SZ_4K);
+}
+
 static ssize_t ctx_restore_post_bb_show(struct config_item *item, char *page)
 {
 	struct xe_config_group_device *dev = to_xe_config_group_device(item);
@@ -623,6 +639,14 @@ static ssize_t wa_bb_store(struct wa_bb wa_bb[static XE_ENGINE_CLASS_MAX],
 	return len;
 }
 
+static ssize_t ctx_restore_mid_bb_store(struct config_item *item,
+					const char *data, size_t sz)
+{
+	struct xe_config_group_device *dev = to_xe_config_group_device(item);
+
+	return wa_bb_store(dev->config.ctx_restore_mid_bb, dev, data, sz);
+}
+
 static ssize_t ctx_restore_post_bb_store(struct config_item *item,
 					 const char *data, size_t sz)
 {
@@ -631,12 +655,14 @@ static ssize_t ctx_restore_post_bb_store(struct config_item *item,
 	return wa_bb_store(dev->config.ctx_restore_post_bb, dev, data, sz);
 }
 
+CONFIGFS_ATTR(, ctx_restore_mid_bb);
 CONFIGFS_ATTR(, ctx_restore_post_bb);
 CONFIGFS_ATTR(, enable_psmi);
 CONFIGFS_ATTR(, engines_allowed);
 CONFIGFS_ATTR(, survivability_mode);
 
 static struct configfs_attribute *xe_config_device_attrs[] = {
+	&attr_ctx_restore_mid_bb,
 	&attr_ctx_restore_post_bb,
 	&attr_enable_psmi,
 	&attr_engines_allowed,
@@ -909,7 +935,19 @@ u32 xe_configfs_get_ctx_restore_mid_bb(struct pci_dev *pdev,
 				       enum xe_engine_class class,
 				       const u32 **cs)
 {
-	return 0;
+	struct xe_config_group_device *dev = find_xe_config_group_device(pdev);
+	u32 len;
+
+	if (!dev)
+		return 0;
+
+	if (cs)
+		*cs = dev->config.ctx_restore_mid_bb[class].cs;
+
+	len = dev->config.ctx_restore_mid_bb[class].len;
+	config_group_put(&dev->group);
+
+	return len;
 }
 
 /**