@@ -282,3 +282,13 @@ Contact: linux-cxl@vger.kernel.org
Description:
(WO) Write a string in the form 'regionZ' to delete that region,
provided it is currently idle / not bound to a driver.
+
+
+What: /sys/bus/cxl/devices/regionZ/uuid
+Date: May, 2022
+KernelVersion: v5.20
+Contact: linux-cxl@vger.kernel.org
+Description:
+ (RW) Write a unique identifier for the region. This field must
+ be set for persistent regions and it must not conflict with the
+ UUID of another region.
@@ -5,6 +5,7 @@
#include <linux/device.h>
#include <linux/module.h>
#include <linux/slab.h>
+#include <linux/uuid.h>
#include <linux/idr.h>
#include <cxl.h>
#include "core.h"
@@ -17,10 +18,126 @@
* Memory ranges, Regions represent the active mapped capacity by the HDM
* Decoder Capability structures throughout the Host Bridges, Switches, and
* Endpoints in the topology.
+ *
+ * Region configuration has ordering constraints. UUID may be set at any time
+ * but is only visible for persistent regions.
+ */
+
+/*
+ * All changes to the interleave configuration occur with this lock held
+ * for write.
*/
+static DECLARE_RWSEM(cxl_region_rwsem);
static struct cxl_region *to_cxl_region(struct device *dev);
+static ssize_t uuid_show(struct device *dev, struct device_attribute *attr,
+ char *buf)
+{
+ struct cxl_region *cxlr = to_cxl_region(dev);
+ struct cxl_region_params *p = &cxlr->params;
+ ssize_t rc;
+
+ rc = down_read_interruptible(&cxl_region_rwsem);
+ if (rc)
+ return rc;
+ rc = sysfs_emit(buf, "%pUb\n", &p->uuid);
+ up_read(&cxl_region_rwsem);
+
+ return rc;
+}
+
+static int is_dup(struct device *match, void *data)
+{
+ struct cxl_region_params *p;
+ struct cxl_region *cxlr;
+ uuid_t *uuid = data;
+
+ if (!is_cxl_region(match))
+ return 0;
+
+ lockdep_assert_held(&cxl_region_rwsem);
+ cxlr = to_cxl_region(match);
+ p = &cxlr->params;
+
+ if (uuid_equal(&p->uuid, uuid)) {
+ dev_dbg(match, "already has uuid: %pUb\n", uuid);
+ return -EBUSY;
+ }
+
+ return 0;
+}
+
+static ssize_t uuid_store(struct device *dev, struct device_attribute *attr,
+ const char *buf, size_t len)
+{
+ struct cxl_region *cxlr = to_cxl_region(dev);
+ struct cxl_region_params *p = &cxlr->params;
+ uuid_t temp;
+ ssize_t rc;
+
+ if (len != UUID_STRING_LEN + 1)
+ return -EINVAL;
+
+ rc = uuid_parse(buf, &temp);
+ if (rc)
+ return rc;
+
+ if (uuid_is_null(&temp))
+ return -EINVAL;
+
+ rc = down_write_killable(&cxl_region_rwsem);
+ if (rc)
+ return rc;
+
+ if (uuid_equal(&p->uuid, &temp))
+ goto out;
+
+ rc = -EBUSY;
+ if (p->state >= CXL_CONFIG_ACTIVE)
+ goto out;
+
+ rc = bus_for_each_dev(&cxl_bus_type, NULL, &temp, is_dup);
+ if (rc < 0)
+ goto out;
+
+ uuid_copy(&p->uuid, &temp);
+out:
+ up_write(&cxl_region_rwsem);
+
+ if (rc)
+ return rc;
+ return len;
+}
+static DEVICE_ATTR_RW(uuid);
+
+static umode_t cxl_region_visible(struct kobject *kobj, struct attribute *a,
+ int n)
+{
+ struct device *dev = kobj_to_dev(kobj);
+ struct cxl_region *cxlr = to_cxl_region(dev);
+
+ if (a == &dev_attr_uuid.attr && cxlr->mode != CXL_DECODER_PMEM)
+ return 0;
+ return a->mode;
+}
+
+static struct attribute *cxl_region_attrs[] = {
+ &dev_attr_uuid.attr,
+ NULL,
+};
+
+static const struct attribute_group cxl_region_group = {
+ .attrs = cxl_region_attrs,
+ .is_visible = cxl_region_visible,
+};
+
+static const struct attribute_group *region_groups[] = {
+ &cxl_base_attribute_group,
+ &cxl_region_group,
+ NULL,
+};
+
static void cxl_region_release(struct device *dev)
{
struct cxl_region *cxlr = to_cxl_region(dev);
@@ -32,6 +149,7 @@ static void cxl_region_release(struct device *dev)
static const struct device_type cxl_region_type = {
.name = "cxl_region",
.release = cxl_region_release,
+ .groups = region_groups
};
bool is_cxl_region(struct device *dev)
@@ -295,18 +295,43 @@ struct cxl_root_decoder {
struct cxl_switch_decoder cxlsd;
};
+/*
+ * enum cxl_config_state - State machine for region configuration
+ * @CXL_CONFIG_IDLE: Any sysfs attribute can be written freely
+ * @CXL_CONFIG_ACTIVE: All targets have been added the region is now
+ * active
+ */
+enum cxl_config_state {
+ CXL_CONFIG_IDLE,
+ CXL_CONFIG_ACTIVE,
+};
+
+/**
+ * struct cxl_region_params - region settings
+ * @state: allow the driver to lockdown further parameter changes
+ * @uuid: unique id for persistent regions
+ *
+ * State transitions are protected by the cxl_region_rwsem
+ */
+struct cxl_region_params {
+ enum cxl_config_state state;
+ uuid_t uuid;
+};
+
/**
* struct cxl_region - CXL region
* @dev: This region's device
* @id: This region's id. Id is globally unique across all regions
* @mode: Endpoint decoder allocation / access mode
* @type: Endpoint decoder target type
+ * @params: active + config params for the region
*/
struct cxl_region {
struct device dev;
int id;
enum cxl_decoder_mode mode;
enum cxl_decoder_type type;
+ struct cxl_region_params params;
};
/**