EDAC: Add a memory repair control feature

Add a generic EDAC memory repair control driver to manage memory repairs in
the system, such as CXL Post Package Repair (PPR) and other soft and hard PPR
features.

For example, a CXL device with DRAM components that support PPR features may
implement PPR maintenance operations. DRAM components may support two types of
PPR:

 - hard PPR, for a permanent row repair, and
 - soft PPR,  for a temporary row repair.

Soft PPR is much faster than hard PPR, but the repair is lost with a power
cycle.

When a CXL device detects an error in a memory, it may report the need for
a repair maintenance operation by using an event record where the "maintenance
needed" flag is set. The event records contain the device physical
address (DPA) and other optional attributes of the memory to repair.

The kernel will report the corresponding CXL general media or DRAM trace event
to userspace, and userspace tools (e.g. rasdaemon) will initiate a repair
operation in response to the device request via the sysfs repair control.

Device with memory repair features registers with EDAC device driver, which
retrieves a memory repair descriptor from EDAC memory repair driver and exposes
the sysfs repair control attributes to userspace in

  /sys/bus/edac/devices/<dev-name>/mem_repairX/.

The common memory repair control interface abstracts the control of arbitrary
memory repair functionality into a standardized set of functions.  The sysfs
memory repair attribute nodes are only available if the client driver has
implemented the corresponding attribute callback function and provided
operations to the EDAC device driver during registration.

  [ bp: Massage, fixup edac_dev_register() retvals, merge
    write_overflow fix to mem_repair_create_desc() ]

Signed-off-by: Shiju Jose <shiju.jose@huawei.com>
Signed-off-by: Borislav Petkov (AMD) <bp@alien8.de>
Link: https://lore.kernel.org/r/20250212143654.1893-5-shiju.jose@huawei.com

1 files changed, 74 insertions, 0 deletions

diff --git a/include/linux/edac.h b/include/linux/edac.h
index f8346014c14e..cfb2ef41ab95 100644
--- a/include/linux/edac.h
+++ b/include/linux/edac.h
@@ -668,6 +668,7 @@ static inline struct dimm_info *edac_get_dimm(struct mem_ctl_info *mci,
 enum edac_dev_feat {
 	RAS_FEAT_SCRUB,
 	RAS_FEAT_ECS,
+	RAS_FEAT_MEM_REPAIR,
 	RAS_FEAT_MAX
 };
 
@@ -743,11 +744,82 @@ static inline int edac_ecs_get_desc(struct device *ecs_dev,
 { return -EOPNOTSUPP; }
 #endif /* CONFIG_EDAC_ECS */
 
+enum edac_mem_repair_type {
+	EDAC_REPAIR_MAX
+};
+
+enum edac_mem_repair_cmd {
+	EDAC_DO_MEM_REPAIR = 1,
+};
+
+/**
+ * struct edac_mem_repair_ops - memory repair operations
+ * (all elements are optional except do_repair, set_hpa/set_dpa)
+ * @get_repair_type: get the memory repair type, listed in
+ *			 enum edac_mem_repair_function.
+ * @get_persist_mode: get the current persist mode.
+ *		      false - Soft repair type (temporary repair).
+ *		      true - Hard memory repair type (permanent repair).
+ * @set_persist_mode: set the persist mode of the memory repair instance.
+ * @get_repair_safe_when_in_use: get whether memory media is accessible and
+ *				 data is retained during repair operation.
+ * @get_hpa: get current host physical address (HPA) of memory to repair.
+ * @set_hpa: set host physical address (HPA) of memory to repair.
+ * @get_min_hpa: get the minimum supported host physical address (HPA).
+ * @get_max_hpa: get the maximum supported host physical address (HPA).
+ * @get_dpa: get current device physical address (DPA) of memory to repair.
+ * @set_dpa: set device physical address (DPA) of memory to repair.
+ *	     In some states of system configuration (e.g. before address decoders
+ *	     have been configured), memory devices (e.g. CXL) may not have an active
+ *	     mapping in the host physical address map. As such, the memory
+ *	     to repair must be identified by a device specific physical addressing
+ *	     scheme using a device physical address(DPA). The DPA and other control
+ *	     attributes to use for the repair operations will be presented in related
+ *	     error records.
+ * @get_min_dpa: get the minimum supported device physical address (DPA).
+ * @get_max_dpa: get the maximum supported device physical address (DPA).
+ * @get_nibble_mask: get current nibble mask of memory to repair.
+ * @set_nibble_mask: set nibble mask of memory to repair.
+ * @do_repair: Issue memory repair operation for the HPA/DPA and
+ *	       other control attributes set for the memory to repair.
+ *
+ * All elements are optional except do_repair and at least one of set_hpa/set_dpa.
+ */
+struct edac_mem_repair_ops {
+	int (*get_repair_type)(struct device *dev, void *drv_data, const char **type);
+	int (*get_persist_mode)(struct device *dev, void *drv_data, bool *persist);
+	int (*set_persist_mode)(struct device *dev, void *drv_data, bool persist);
+	int (*get_repair_safe_when_in_use)(struct device *dev, void *drv_data, bool *safe);
+	int (*get_hpa)(struct device *dev, void *drv_data, u64 *hpa);
+	int (*set_hpa)(struct device *dev, void *drv_data, u64 hpa);
+	int (*get_min_hpa)(struct device *dev, void *drv_data, u64 *hpa);
+	int (*get_max_hpa)(struct device *dev, void *drv_data, u64 *hpa);
+	int (*get_dpa)(struct device *dev, void *drv_data, u64 *dpa);
+	int (*set_dpa)(struct device *dev, void *drv_data, u64 dpa);
+	int (*get_min_dpa)(struct device *dev, void *drv_data, u64 *dpa);
+	int (*get_max_dpa)(struct device *dev, void *drv_data, u64 *dpa);
+	int (*get_nibble_mask)(struct device *dev, void *drv_data, u32 *val);
+	int (*set_nibble_mask)(struct device *dev, void *drv_data, u32 val);
+	int (*do_repair)(struct device *dev, void *drv_data, u32 val);
+};
+
+#if IS_ENABLED(CONFIG_EDAC_MEM_REPAIR)
+int edac_mem_repair_get_desc(struct device *dev,
+			     const struct attribute_group **attr_groups,
+			     u8 instance);
+#else
+static inline int edac_mem_repair_get_desc(struct device *dev,
+					   const struct attribute_group **attr_groups,
+					   u8 instance)
+{ return -EOPNOTSUPP; }
+#endif /* CONFIG_EDAC_MEM_REPAIR */
+
 /* EDAC device feature information structure */
 struct edac_dev_data {
 	union {
 		const struct edac_scrub_ops *scrub_ops;
 		const struct edac_ecs_ops *ecs_ops;
+		const struct edac_mem_repair_ops *mem_repair_ops;
 	};
 	u8 instance;
 	void *private;
@@ -758,6 +830,7 @@ struct edac_dev_feat_ctx {
 	void *private;
 	struct edac_dev_data *scrub;
 	struct edac_dev_data ecs;
+	struct edac_dev_data *mem_repair;
 };
 
 struct edac_dev_feature {
@@ -766,6 +839,7 @@ struct edac_dev_feature {
 	union {
 		const struct edac_scrub_ops *scrub_ops;
 		const struct edac_ecs_ops *ecs_ops;
+		const struct edac_mem_repair_ops *mem_repair_ops;
 	};
 	void *ctx;
 	struct edac_ecs_ex_info ecs_info;