Regions are created as a child of the decoder that encompasses an
address space with constraints. Regions have a number of attributes that
must be configured before the region can be activated.
The ABI is not meant to be secure, but is meant to avoid accidental
races. As a result, a buggy process may create a region by name that was
allocated by a different process. However, multiple processes which are
trying not to race with each other shouldn't need special
synchronization to do so.
// Allocate a new region name
region=$(cat /sys/bus/cxl/devices/decoder0.0/create_region)
// Create a new region by name
echo $region > /sys/bus/cxl/devices/decoder0.0/create_region
// Region now exists in sysfs
stat -t /sys/bus/cxl/devices/decoder0.0/$region
// Delete the region, and name
echo $region > /sys/bus/cxl/devices/decoder0.0/delete_region
Signed-off-by: Ben Widawsky <ben.widawsky@xxxxxxxxx>
---
Changes since v2:
- Rename 'region' variables to 'cxlr'
- Update ABI docs for possible actual upstream version
---
Documentation/ABI/testing/sysfs-bus-cxl | 24 ++
.../driver-api/cxl/memory-devices.rst | 11 +
drivers/cxl/core/Makefile | 1 +
drivers/cxl/core/core.h | 3 +
drivers/cxl/core/port.c | 16 ++
drivers/cxl/core/region.c | 208 ++++++++++++++++++
drivers/cxl/cxl.h | 9 +
drivers/cxl/region.h | 38 ++++
tools/testing/cxl/Kbuild | 1 +
9 files changed, 311 insertions(+)
create mode 100644 drivers/cxl/core/region.c
create mode 100644 drivers/cxl/region.h
diff --git a/Documentation/ABI/testing/sysfs-bus-cxl b/Documentation/ABI/testing/sysfs-bus-cxl
index 7c2b846521f3..dcc728458936 100644
--- a/Documentation/ABI/testing/sysfs-bus-cxl
+++ b/Documentation/ABI/testing/sysfs-bus-cxl
@@ -163,3 +163,27 @@ Description:
memory (type-3). The 'target_type' attribute indicates the
current setting which may dynamically change based on what
memory regions are activated in this decode hierarchy.
+
+What: /sys/bus/cxl/devices/decoderX.Y/create_region
+Date: August, 2021
+KernelVersion: v5.18
+Contact: linux-cxl@xxxxxxxxxxxxxxx
+Description:
+ Creates a new CXL region. Writing a value of the form
+ "regionX.Y:Z" will create a new uninitialized region that will
+ be mapped by the CXL decoderX.Y. Reading from this node will
+ return a newly allocated region name. In order to create a
+ region (writing) you must use a value returned from reading the
+ node. Regions must be created for root decoders, and must
+ subsequently configured and bound to a region driver before they
+ can be used.
+
+What: /sys/bus/cxl/devices/decoderX.Y/delete_region
+Date: August, 2021
+KernelVersion: v5.18
+Contact: linux-cxl@xxxxxxxxxxxxxxx
+Description:
+ Deletes the named region. A region must be unbound from the
+ region driver before being deleted. The attributes expects a
+ region in the form "regionX.Y:Z". The region's name, allocated
+ by reading create_region, will also be released.
diff --git a/Documentation/driver-api/cxl/memory-devices.rst b/Documentation/driver-api/cxl/memory-devices.rst
index db476bb170b6..66ddc58a21b1 100644
--- a/Documentation/driver-api/cxl/memory-devices.rst
+++ b/Documentation/driver-api/cxl/memory-devices.rst
@@ -362,6 +362,17 @@ CXL Core
.. kernel-doc:: drivers/cxl/core/mbox.c
:doc: cxl mbox
+CXL Regions
+-----------
+.. kernel-doc:: drivers/cxl/region.h
+ :identifiers:
+
+.. kernel-doc:: drivers/cxl/core/region.c
+ :doc: cxl core region
+
+.. kernel-doc:: drivers/cxl/core/region.c
+ :identifiers:
+
External Interfaces
===================
diff --git a/drivers/cxl/core/Makefile b/drivers/cxl/core/Makefile
index 6d37cd78b151..39ce8f2f2373 100644
--- a/drivers/cxl/core/Makefile
+++ b/drivers/cxl/core/Makefile
@@ -4,6 +4,7 @@ obj-$(CONFIG_CXL_BUS) += cxl_core.o
ccflags-y += -I$(srctree)/drivers/cxl
cxl_core-y := port.o
cxl_core-y += pmem.o
+cxl_core-y += region.o
cxl_core-y += regs.o
cxl_core-y += memdev.o
cxl_core-y += mbox.o
diff --git a/drivers/cxl/core/core.h b/drivers/cxl/core/core.h
index efbaa851929d..35fd08d560e2 100644
--- a/drivers/cxl/core/core.h
+++ b/drivers/cxl/core/core.h
@@ -10,6 +10,9 @@ extern const struct device_type cxl_memdev_type;
extern struct attribute_group cxl_base_attribute_group;
+extern struct device_attribute dev_attr_create_region;
+extern struct device_attribute dev_attr_delete_region;
+
struct cxl_send_command;
struct cxl_mem_query_commands;
int cxl_query_cmd(struct cxl_memdev *cxlmd,
diff --git a/drivers/cxl/core/port.c b/drivers/cxl/core/port.c
index 631dec0fa79e..0826208b2bdf 100644
--- a/drivers/cxl/core/port.c
+++ b/drivers/cxl/core/port.c
@@ -215,6 +215,8 @@ static struct attribute_group cxl_decoder_base_attribute_group = {
};
static struct attribute *cxl_decoder_root_attrs[] = {
+ &dev_attr_create_region.attr,
+ &dev_attr_delete_region.attr,
&dev_attr_cap_pmem.attr,
&dev_attr_cap_ram.attr,
&dev_attr_cap_type2.attr,
@@ -267,11 +269,23 @@ static const struct attribute_group *cxl_decoder_endpoint_attribute_groups[] = {
NULL,
};
+static int delete_region(struct device *dev, void *arg)
+{
+ struct cxl_decoder *cxld = to_cxl_decoder(dev->parent);
+
+ return cxl_delete_region(cxld, dev_name(dev));
+}
+
static void cxl_decoder_release(struct device *dev)
{
struct cxl_decoder *cxld = to_cxl_decoder(dev);
struct cxl_port *port = to_cxl_port(dev->parent);
+ device_for_each_child(&cxld->dev, cxld, delete_region);
+
+ dev_WARN_ONCE(dev, !ida_is_empty(&cxld->region_ida),
+ "Lost track of a region");
+
ida_free(&port->decoder_ida, cxld->id);
kfree(cxld);
}
@@ -1194,6 +1208,8 @@ static struct cxl_decoder *cxl_decoder_alloc(struct cxl_port *port,
cxld->target_type = CXL_DECODER_EXPANDER;
cxld->platform_res = (struct resource)DEFINE_RES_MEM(0, 0);
+ ida_init(&cxld->region_ida);
+
return cxld;
err:
kfree(cxld);
diff --git a/drivers/cxl/core/region.c b/drivers/cxl/core/region.c
new file mode 100644
index 000000000000..1a448543db0d
--- /dev/null
+++ b/drivers/cxl/core/region.c
@@ -0,0 +1,208 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/* Copyright(c) 2021 Intel Corporation. All rights reserved. */
+#include <linux/io-64-nonatomic-lo-hi.h>
+#include <linux/device.h>
+#include <linux/module.h>
+#include <linux/slab.h>
+#include <linux/idr.h>
+#include <region.h>
+#include <cxl.h>
+#include "core.h"
+
+/**
+ * DOC: cxl core region
+ *
+ * Regions are managed through the Linux device model. Each region instance is a
+ * unique struct device. CXL core provides functionality to create, destroy, and
+ * configure regions. This is all implemented here. Binding a region
+ * (programming the hardware) is handled by a separate region driver.
+ */
+
+static void cxl_region_release(struct device *dev);
+
+static const struct device_type cxl_region_type = {
+ .name = "cxl_region",
+ .release = cxl_region_release,
+};
+
+static ssize_t create_region_show(struct device *dev,
+ struct device_attribute *attr, char *buf)
+{
+ struct cxl_port *port = to_cxl_port(dev->parent);
+ struct cxl_decoder *cxld = to_cxl_decoder(dev);
+ int rc;
+
+ if (dev_WARN_ONCE(dev, !is_root_decoder(dev),
+ "Invalid decoder selected for region.")) {
+ return -ENODEV;
+ }
+
+ rc = ida_alloc(&cxld->region_ida, GFP_KERNEL);
+ if (rc < 0) {
+ dev_err(&cxld->dev, "Couldn't get a new id\n");
+ return rc;
+ }
+
+ return sysfs_emit(buf, "region%d.%d:%d\n", port->id, cxld->id, rc);
+}
+
+static ssize_t create_region_store(struct device *dev,
+ struct device_attribute *attr,
+ const char *buf, size_t len)
+{
+ struct cxl_port *port = to_cxl_port(dev->parent);
+ struct cxl_decoder *cxld = to_cxl_decoder(dev);
+ int decoder_id, port_id, region_id;
+ struct cxl_region *cxlr;
+ ssize_t rc;
+
+ if (sscanf(buf, "region%d.%d:%d", &port_id, &decoder_id, ®ion_id) != 3)
+ return -EINVAL;
+
+ if (decoder_id != cxld->id)
+ return -EINVAL;
+
+ if (port_id != port->id)
+ return -EINVAL;
+
+ cxlr = cxl_alloc_region(cxld, region_id);
+ if (IS_ERR(cxlr))
+ return PTR_ERR(cxlr);
+
+ rc = cxl_add_region(cxld, cxlr);
+ if (rc) {
+ kfree(cxlr);
+ return rc;
+ }
+
+ return len;
+}
+DEVICE_ATTR_RW(create_region);
+
+static ssize_t delete_region_store(struct device *dev,
+ struct device_attribute *attr,
+ const char *buf, size_t len)
+{
+ struct cxl_decoder *cxld = to_cxl_decoder(dev);
+ int rc;
+
+ rc = cxl_delete_region(cxld, buf);
+ if (rc)
+ return rc;
+
+ return len;
+}
+DEVICE_ATTR_WO(delete_region);
+
+struct cxl_region *to_cxl_region(struct device *dev)
+{
+ if (dev_WARN_ONCE(dev, dev->type != &cxl_region_type,
+ "not a cxl_region device\n"))
+ return NULL;
+
+ return container_of(dev, struct cxl_region, dev);
+}
+EXPORT_SYMBOL_GPL(to_cxl_region);
+
+static void cxl_region_release(struct device *dev)
+{
+ struct cxl_decoder *cxld = to_cxl_decoder(dev->parent);
+ struct cxl_region *cxlr = to_cxl_region(dev);
+
+ ida_free(&cxld->region_ida, cxlr->id);
+ kfree(cxlr);
+}
+
+struct cxl_region *cxl_alloc_region(struct cxl_decoder *cxld, int id)
+{
+ struct cxl_region *cxlr;
+
+ cxlr = kzalloc(sizeof(*cxlr), GFP_KERNEL);
+ if (!cxlr)
+ return ERR_PTR(-ENOMEM);
+
+ cxlr->id = id;
+
+ return cxlr;
+}
+
+/**
+ * cxl_add_region - Adds a region to a decoder
+ * @cxld: Parent decoder.
+ * @cxlr: Region to be added to the decoder.
+ *
+ * This is the second step of region initialization. Regions exist within an
+ * address space which is mapped by a @cxld. That @cxld must be a root decoder,
+ * and it enforces constraints upon the region as it is configured.
+ *
+ * Return: 0 if the region was added to the @cxld, else returns negative error
+ * code. The region will be named "regionX.Y.Z" where X is the port, Y is the
+ * decoder id, and Z is the region number.
+ */
+int cxl_add_region(struct cxl_decoder *cxld, struct cxl_region *cxlr)
+{
+ struct cxl_port *port = to_cxl_port(cxld->dev.parent);
+ struct device *dev = &cxlr->dev;
+ int rc;
+
+ device_initialize(dev);
+ dev->parent = &cxld->dev;
+ device_set_pm_not_required(dev);
+ dev->bus = &cxl_bus_type;
+ dev->type = &cxl_region_type;
+ rc = dev_set_name(dev, "region%d.%d:%d", port->id, cxld->id, cxlr->id);
+ if (rc)
+ goto err;
+
+ rc = device_add(dev);
+ if (rc)
+ goto err;
+
+ dev_dbg(dev, "Added to %s\n", dev_name(&cxld->dev));
+
+ return 0;
+
+err:
+ put_device(dev);
+ return rc;
+}
+
+static struct cxl_region *cxl_find_region_by_name(struct cxl_decoder *cxld,
+ const char *name)
+{
+ struct device *region_dev;
+
+ region_dev = device_find_child_by_name(&cxld->dev, name);
+ if (!region_dev)
+ return ERR_PTR(-ENOENT);
+
+ return to_cxl_region(region_dev);
+}
+
+/**
+ * cxl_delete_region - Deletes a region
+ * @cxld: Parent decoder
+ * @region_name: Named region, ie. regionX.Y:Z
+ */
+int cxl_delete_region(struct cxl_decoder *cxld, const char *region_name)
+{
+ struct cxl_region *cxlr;
+
+ device_lock(&cxld->dev);
+
+ cxlr = cxl_find_region_by_name(cxld, region_name);
+ if (IS_ERR(cxlr)) {
+ device_unlock(&cxld->dev);
+ return PTR_ERR(cxlr);
+ }
+
+ dev_dbg(&cxld->dev, "Requested removal of %s from %s\n",
+ dev_name(&cxlr->dev), dev_name(&cxld->dev));
+
+ device_unregister(&cxlr->dev);
+ device_unlock(&cxld->dev);
+
+ put_device(&cxlr->dev);
+
+ return 0;
+}
diff --git a/drivers/cxl/cxl.h b/drivers/cxl/cxl.h
index 13fb06849199..b9f0099c1f39 100644
--- a/drivers/cxl/cxl.h
+++ b/drivers/cxl/cxl.h
@@ -221,6 +221,7 @@ enum cxl_decoder_type {
* @target_type: accelerator vs expander (type2 vs type3) selector
* @flags: memory type capabilities and locking
* @target_lock: coordinate coherent reads of the target list
+ * @region_ida: allocator for region ids.
* @nr_targets: number of elements in @target
* @target: active ordered target list in current decoder configuration
*/
@@ -236,6 +237,7 @@ struct cxl_decoder {
enum cxl_decoder_type target_type;
unsigned long flags;
seqlock_t target_lock;
+ struct ida region_ida;
int nr_targets;
struct cxl_dport *target[];
};
@@ -323,6 +325,13 @@ struct cxl_ep {
struct list_head list;
};
+bool is_cxl_region(struct device *dev);
+struct cxl_region *to_cxl_region(struct device *dev);
+struct cxl_region *cxl_alloc_region(struct cxl_decoder *cxld,
+ int interleave_ways);
+int cxl_add_region(struct cxl_decoder *cxld, struct cxl_region *cxlr);
+int cxl_delete_region(struct cxl_decoder *cxld, const char *region);
+
static inline bool is_cxl_root(struct cxl_port *port)
{
return port->uport == port->dev.parent;
diff --git a/drivers/cxl/region.h b/drivers/cxl/region.h
new file mode 100644
index 000000000000..eb1249e3c1d4
--- /dev/null
+++ b/drivers/cxl/region.h
@@ -0,0 +1,38 @@
+/* SPDX-License-Identifier: GPL-2.0-only */
+/* Copyright(c) 2021 Intel Corporation. */
+#ifndef __CXL_REGION_H__
+#define __CXL_REGION_H__
+
+#include <linux/uuid.h>
+
+#include "cxl.h"
+
+/**
+ * struct cxl_region - CXL region
+ * @dev: This region's device.
+ * @id: This regions id. Id is globally unique across all regions.
+ * @list: Node in decoder's region list.
+ * @res: Resource this region carves out of the platform decode range.
+ * @config: HDM decoder program config
+ * @config.size: Size of the region determined from LSA or userspace.
+ * @config.uuid: The UUID for this region.
+ * @config.interleave_ways: Number of interleave ways this region is configured for.
+ * @config.interleave_granularity: Interleave granularity of region
+ * @config.targets: The memory devices comprising the region.
+ */
+struct cxl_region {
+ struct device dev;
+ int id;
+ struct list_head list;
+ struct resource *res;
+
+ struct {
+ u64 size;
+ uuid_t uuid;
+ int interleave_ways;
+ int interleave_granularity;
+ struct cxl_memdev *targets[CXL_DECODER_MAX_INTERLEAVE];
+ } config;
+};
+
+#endif
diff --git a/tools/testing/cxl/Kbuild b/tools/testing/cxl/Kbuild
index 82e49ab0937d..3fe6d34e6d59 100644
--- a/tools/testing/cxl/Kbuild
+++ b/tools/testing/cxl/Kbuild
@@ -46,6 +46,7 @@ cxl_core-y += $(CXL_CORE_SRC)/memdev.o
cxl_core-y += $(CXL_CORE_SRC)/mbox.o
cxl_core-y += $(CXL_CORE_SRC)/pci.o
cxl_core-y += $(CXL_CORE_SRC)/hdm.o
+cxl_core-y += $(CXL_CORE_SRC)/region.o
cxl_core-y += config_check.o
obj-m += test/
--
2.35.0
