@@ -127,3 +127,26 @@ 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: June, 2021
+KernelVersion: v5.16
+Contact: linux-cxl@vger.kernel.org
+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 subsequently configured and bound to a
+ region driver before they can be used.
+
+What: /sys/bus/cxl/devices/decoderX.Y/delete_region
+Date: June, 2021
+KernelVersion: v5.16
+Contact: linux-cxl@vger.kernel.org
+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.
@@ -65,6 +65,17 @@ 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
===================
@@ -4,6 +4,7 @@ obj-$(CONFIG_CXL_BUS) += cxl_core.o
ccflags-y += -DDEFAULT_SYMBOL_NAMESPACE=CXL -I$(srctree)/drivers/cxl
cxl_core-y := bus.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
@@ -131,6 +131,74 @@ static ssize_t target_list_show(struct device *dev,
}
static DEVICE_ATTR_RO(target_list);
+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_decoder *cxld = to_cxl_decoder(dev);
+ int decoder, port, region_id;
+ struct cxl_region *region;
+ ssize_t rc;
+
+ if (sscanf(buf, "region%d.%d:%d", &decoder, &port, ®ion_id) != 3)
+ return -EINVAL;
+
+ if (decoder != cxld->id)
+ return -EINVAL;
+
+ if (cxld->id != port)
+ return -EINVAL;
+
+ region = cxl_alloc_region(cxld, region_id);
+ if (IS_ERR(region))
+ return PTR_ERR(region);
+
+ rc = cxl_add_region(cxld, region);
+ if (rc) {
+ kfree(region);
+ return rc;
+ }
+
+ return len;
+}
+static 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;
+}
+static DEVICE_ATTR_WO(delete_region);
+
static struct attribute *cxl_decoder_base_attrs[] = {
&dev_attr_start.attr,
&dev_attr_size.attr,
@@ -144,6 +212,8 @@ 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,
@@ -184,11 +254,23 @@ 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);
}
@@ -722,6 +804,8 @@ struct cxl_decoder *cxl_decoder_alloc(struct cxl_port *port,
else
dev->type = &cxl_decoder_root_type;
+ ida_init(&cxld->region_ida);
+
return cxld;
err:
kfree(cxld);
new file mode 100644
@@ -0,0 +1,139 @@
+// 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>
+
+/**
+ * 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,
+};
+
+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 *region = to_cxl_region(dev);
+
+ ida_free(&cxld->region_ida, region->id);
+ kfree(region);
+}
+
+struct cxl_region *cxl_alloc_region(struct cxl_decoder *cxld, int id)
+{
+ struct cxl_region *region;
+
+ region = kzalloc(sizeof(*region), GFP_KERNEL);
+ if (!region)
+ return ERR_PTR(-ENOMEM);
+
+ region->id = id;
+
+ return region;
+}
+
+/**
+ * cxl_add_region - Adds a region to a decoder
+ * @cxld: Parent decoder.
+ * @region: 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 *region)
+{
+ struct cxl_port *port = to_cxl_port(cxld->dev.parent);
+ struct device *dev = ®ion->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,
+ region->id);
+ if (rc)
+ goto err;
+
+ rc = device_add(dev);
+ if (rc)
+ goto err;
+
+ dev_dbg(dev, "Added %s to %s\n", dev_name(dev), 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 *region;
+
+ device_lock(&cxld->dev);
+
+ region = cxl_find_region_by_name(cxld, region_name);
+ if (IS_ERR(region)) {
+ device_unlock(&cxld->dev);
+ return PTR_ERR(region);
+ }
+
+ dev_dbg(&cxld->dev, "Requested removal of %s from %s\n",
+ dev_name(®ion->dev), dev_name(&cxld->dev));
+
+ device_unregister(®ion->dev);
+ device_unlock(&cxld->dev);
+
+ put_device(®ion->dev);
+
+ return 0;
+}
@@ -217,6 +217,7 @@ enum cxl_decoder_type {
* @interleave_granularity: data stride per dport
* @target_type: accelerator vs expander (type2 vs type3) selector
* @flags: memory type capabilities and locking
+ * @region_ida: allocator for region ids.
* @nr_targets: number of elements in @target
* @target: active ordered target list in current decoder configuration
*/
@@ -228,6 +229,7 @@ struct cxl_decoder {
int interleave_granularity;
enum cxl_decoder_type target_type;
unsigned long flags;
+ struct ida region_ida;
const int nr_targets;
struct cxl_dport *target[];
};
@@ -302,6 +304,13 @@ struct cxl_dport {
struct list_head root_port_link;
};
+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 *region);
+int cxl_delete_region(struct cxl_decoder *cxld, const char *region);
+
struct cxl_port *to_cxl_port(struct device *dev);
struct cxl_port *devm_cxl_add_port(struct device *host, struct device *uport,
resource_size_t component_reg_phys,
new file mode 100644
@@ -0,0 +1,37 @@
+/* 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: Address space consumed by this region.
+ * @size: Size of the region determined from LSA or userspace.
+ * @uuid: The UUID for this region.
+ * @eniw: Number of interleave ways this region is configured for.
+ * @ig: Interleave granularity of region
+ * @targets: The memory devices comprising the region.
+ */
+struct cxl_region {
+ struct device dev;
+ int id;
+ struct list_head list;
+
+ struct {
+ struct resource *res;
+ u64 size;
+ uuid_t uuid;
+ int eniw;
+ int ig;
+ struct cxl_memdev *targets[CXL_DECODER_MAX_INTERLEAVE];
+ };
+};
+
+#endif
@@ -32,6 +32,7 @@ cxl_core-y += $(CXL_CORE_SRC)/regs.o
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)/region.o
cxl_core-y += config_check.o
cxl_core-y += mock_pmem.o
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 After creating a region, it will show up in sysfs /sys/bus/cxl/devices/ ├── decoder0.0 -> ../../../devices/platform/ACPI0017:00/root0/decoder0.0 ├── decoder1.0 -> ../../../devices/platform/ACPI0017:00/root0/port1/decoder1.0 ├── decoder2.0 -> ../../../devices/platform/ACPI0017:00/root0/port1/port2/decoder2.0 ├── mem0 -> ../../../devices/pci0000:34/0000:34:00.0/0000:35:00.0/mem0 ├── pmem0 -> ../../../devices/pci0000:34/0000:34:00.0/0000:35:00.0/mem0/pmem0 ├── port1 -> ../../../devices/platform/ACPI0017:00/root0/port1 ├── port2 -> ../../../devices/platform/ACPI0017:00/root0/port1/port2 └── root0 -> ../../../devices/platform/ACPI0017:00/root0 Signed-off-by: Ben Widawsky <ben.widawsky@intel.com> --- Documentation/ABI/testing/sysfs-bus-cxl | 23 +++ .../driver-api/cxl/memory-devices.rst | 11 ++ drivers/cxl/core/Makefile | 1 + drivers/cxl/core/bus.c | 84 +++++++++++ drivers/cxl/core/region.c | 139 ++++++++++++++++++ drivers/cxl/cxl.h | 9 ++ drivers/cxl/region.h | 37 +++++ tools/testing/cxl/Kbuild | 1 + 8 files changed, 305 insertions(+) create mode 100644 drivers/cxl/core/region.c create mode 100644 drivers/cxl/region.h