diff --git a/MAINTAINERS b/MAINTAINERS
index 7f86d02cb427ab3b70937af638f8bc5c2f4d232f..73a9f3401e0e5ad924895726ee4cadb1892e58d5 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -6035,6 +6035,7 @@ M: Dan Williams <dan.j.williams@intel.com>
M: Vishal Verma <vishal.l.verma@intel.com>
M: Dave Jiang <dave.jiang@intel.com>
L: nvdimm@lists.linux.dev
+L: linux-cxl@vger.kernel.org
S: Supported
F: drivers/dax/
diff --git a/drivers/cxl/acpi.c b/drivers/cxl/acpi.c
index ad0849af42d790a528f9c4b2dec4b91c97e400ed..8ebb9a74790d1cc56b98dcfbe0fa2990c2bf0cf5 100644
--- a/drivers/cxl/acpi.c
+++ b/drivers/cxl/acpi.c
@@ -731,7 +731,8 @@ static void __exit cxl_acpi_exit(void)
cxl_bus_drain();
}
-module_init(cxl_acpi_init);
+/* load before dax_hmem sees 'Soft Reserved' CXL ranges */
+subsys_initcall(cxl_acpi_init);
module_exit(cxl_acpi_exit);
MODULE_LICENSE("GPL v2");
MODULE_IMPORT_NS(CXL);
diff --git a/drivers/cxl/core/core.h b/drivers/cxl/core/core.h
index 479f01da6d35b5cdd24a97191d1ee94c7edb997d..cde475e13216ed870b805b08627adee31b8c5a2c 100644
--- a/drivers/cxl/core/core.h
+++ b/drivers/cxl/core/core.h
@@ -15,12 +15,14 @@ extern struct device_attribute dev_attr_create_ram_region;
extern struct device_attribute dev_attr_delete_region;
extern struct device_attribute dev_attr_region;
extern const struct device_type cxl_pmem_region_type;
+extern const struct device_type cxl_dax_region_type;
extern const struct device_type cxl_region_type;
void cxl_decoder_kill_region(struct cxl_endpoint_decoder *cxled);
#define CXL_REGION_ATTR(x) (&dev_attr_##x.attr)
#define CXL_REGION_TYPE(x) (&cxl_region_type)
#define SET_CXL_REGION_ATTR(x) (&dev_attr_##x.attr),
#define CXL_PMEM_REGION_TYPE(x) (&cxl_pmem_region_type)
+#define CXL_DAX_REGION_TYPE(x) (&cxl_dax_region_type)
int cxl_region_init(void);
void cxl_region_exit(void);
#else
@@ -38,6 +40,7 @@ static inline void cxl_region_exit(void)
#define CXL_REGION_TYPE(x) NULL
#define SET_CXL_REGION_ATTR(x)
#define CXL_PMEM_REGION_TYPE(x) NULL
+#define CXL_DAX_REGION_TYPE(x) NULL
#endif
struct cxl_send_command;
diff --git a/drivers/cxl/core/port.c b/drivers/cxl/core/port.c
index b45d2796ef353587cb59f1af177ee4722adfafcb..0bb7a5ff724b510b5671bafd015a35dffd491012 100644
--- a/drivers/cxl/core/port.c
+++ b/drivers/cxl/core/port.c
@@ -46,6 +46,8 @@ static int cxl_device_id(struct device *dev)
return CXL_DEVICE_NVDIMM;
if (dev->type == CXL_PMEM_REGION_TYPE())
return CXL_DEVICE_PMEM_REGION;
+ if (dev->type == CXL_DAX_REGION_TYPE())
+ return CXL_DEVICE_DAX_REGION;
if (is_cxl_port(dev)) {
if (is_cxl_root(to_cxl_port(dev)))
return CXL_DEVICE_ROOT;
@@ -2015,6 +2017,6 @@ static void cxl_core_exit(void)
debugfs_remove_recursive(cxl_debugfs);
}
-module_init(cxl_core_init);
+subsys_initcall(cxl_core_init);
module_exit(cxl_core_exit);
MODULE_LICENSE("GPL v2");
diff --git a/drivers/cxl/core/region.c b/drivers/cxl/core/region.c
index 8c29204279e925ec0921383b9ed92583fab7d45f..91bb9ac881ff3a4af2e050b0c2938c46670dc08a 100644
--- a/drivers/cxl/core/region.c
+++ b/drivers/cxl/core/region.c
@@ -2278,6 +2278,75 @@ static struct cxl_pmem_region *cxl_pmem_region_alloc(struct cxl_region *cxlr)
return cxlr_pmem;
}
+static void cxl_dax_region_release(struct device *dev)
+{
+ struct cxl_dax_region *cxlr_dax = to_cxl_dax_region(dev);
+
+ kfree(cxlr_dax);
+}
+
+static const struct attribute_group *cxl_dax_region_attribute_groups[] = {
+ &cxl_base_attribute_group,
+ NULL,
+};
+
+const struct device_type cxl_dax_region_type = {
+ .name = "cxl_dax_region",
+ .release = cxl_dax_region_release,
+ .groups = cxl_dax_region_attribute_groups,
+};
+
+static bool is_cxl_dax_region(struct device *dev)
+{
+ return dev->type == &cxl_dax_region_type;
+}
+
+struct cxl_dax_region *to_cxl_dax_region(struct device *dev)
+{
+ if (dev_WARN_ONCE(dev, !is_cxl_dax_region(dev),
+ "not a cxl_dax_region device\n"))
+ return NULL;
+ return container_of(dev, struct cxl_dax_region, dev);
+}
+EXPORT_SYMBOL_NS_GPL(to_cxl_dax_region, CXL);
+
+static struct lock_class_key cxl_dax_region_key;
+
+static struct cxl_dax_region *cxl_dax_region_alloc(struct cxl_region *cxlr)
+{
+ struct cxl_region_params *p = &cxlr->params;
+ struct cxl_dax_region *cxlr_dax;
+ struct device *dev;
+
+ down_read(&cxl_region_rwsem);
+ if (p->state != CXL_CONFIG_COMMIT) {
+ cxlr_dax = ERR_PTR(-ENXIO);
+ goto out;
+ }
+
+ cxlr_dax = kzalloc(sizeof(*cxlr_dax), GFP_KERNEL);
+ if (!cxlr_dax) {
+ cxlr_dax = ERR_PTR(-ENOMEM);
+ goto out;
+ }
+
+ cxlr_dax->hpa_range.start = p->res->start;
+ cxlr_dax->hpa_range.end = p->res->end;
+
+ dev = &cxlr_dax->dev;
+ cxlr_dax->cxlr = cxlr;
+ device_initialize(dev);
+ lockdep_set_class(&dev->mutex, &cxl_dax_region_key);
+ device_set_pm_not_required(dev);
+ dev->parent = &cxlr->dev;
+ dev->bus = &cxl_bus_type;
+ dev->type = &cxl_dax_region_type;
+out:
+ up_read(&cxl_region_rwsem);
+
+ return cxlr_dax;
+}
+
static void cxlr_pmem_unregister(void *_cxlr_pmem)
{
struct cxl_pmem_region *cxlr_pmem = _cxlr_pmem;
@@ -2362,6 +2431,42 @@ static int devm_cxl_add_pmem_region(struct cxl_region *cxlr)
return rc;
}
+static void cxlr_dax_unregister(void *_cxlr_dax)
+{
+ struct cxl_dax_region *cxlr_dax = _cxlr_dax;
+
+ device_unregister(&cxlr_dax->dev);
+}
+
+static int devm_cxl_add_dax_region(struct cxl_region *cxlr)
+{
+ struct cxl_dax_region *cxlr_dax;
+ struct device *dev;
+ int rc;
+
+ cxlr_dax = cxl_dax_region_alloc(cxlr);
+ if (IS_ERR(cxlr_dax))
+ return PTR_ERR(cxlr_dax);
+
+ dev = &cxlr_dax->dev;
+ rc = dev_set_name(dev, "dax_region%d", cxlr->id);
+ if (rc)
+ goto err;
+
+ rc = device_add(dev);
+ if (rc)
+ goto err;
+
+ dev_dbg(&cxlr->dev, "%s: register %s\n", dev_name(dev->parent),
+ dev_name(dev));
+
+ return devm_add_action_or_reset(&cxlr->dev, cxlr_dax_unregister,
+ cxlr_dax);
+err:
+ put_device(dev);
+ return rc;
+}
+
static int match_decoder_by_range(struct device *dev, void *data)
{
struct range *r1, *r2 = data;
@@ -2624,8 +2729,7 @@ static int cxl_region_probe(struct device *dev)
p->res->start, p->res->end, cxlr,
is_system_ram) > 0)
return 0;
- dev_dbg(dev, "TODO: hookup devdax\n");
- return 0;
+ return devm_cxl_add_dax_region(cxlr);
default:
dev_dbg(&cxlr->dev, "unsupported region mode: %d\n",
cxlr->mode);
diff --git a/drivers/cxl/cxl.h b/drivers/cxl/cxl.h
index 2ac34423523524e623615cdfa7993497ea378099..b1395c46baec0a0d2b250679a32ab792ce6d3028 100644
--- a/drivers/cxl/cxl.h
+++ b/drivers/cxl/cxl.h
@@ -513,6 +513,12 @@ struct cxl_pmem_region {
struct cxl_pmem_region_mapping mapping[];
};
+struct cxl_dax_region {
+ struct device dev;
+ struct cxl_region *cxlr;
+ struct range hpa_range;
+};
+
/**
* struct cxl_port - logical collection of upstream port devices and
* downstream port devices to construct a CXL memory
@@ -707,6 +713,7 @@ void cxl_driver_unregister(struct cxl_driver *cxl_drv);
#define CXL_DEVICE_MEMORY_EXPANDER 5
#define CXL_DEVICE_REGION 6
#define CXL_DEVICE_PMEM_REGION 7
+#define CXL_DEVICE_DAX_REGION 8
#define MODULE_ALIAS_CXL(type) MODULE_ALIAS("cxl:t" __stringify(type) "*")
#define CXL_MODALIAS_FMT "cxl:t%d"
@@ -725,6 +732,7 @@ bool is_cxl_pmem_region(struct device *dev);
struct cxl_pmem_region *to_cxl_pmem_region(struct device *dev);
int cxl_add_to_region(struct cxl_port *root,
struct cxl_endpoint_decoder *cxled);
+struct cxl_dax_region *to_cxl_dax_region(struct device *dev);
#else
static inline bool is_cxl_pmem_region(struct device *dev)
{
@@ -739,6 +747,10 @@ static inline int cxl_add_to_region(struct cxl_port *root,
{
return 0;
}
+static inline struct cxl_dax_region *to_cxl_dax_region(struct device *dev)
+{
+ return NULL;
+}
#endif
/*
diff --git a/drivers/dax/Kconfig b/drivers/dax/Kconfig
index 1163eb62e5f69e3be7205950e475f98fe12a6c43..bd06e16c7ac82ad47add908c16bceae6ec67669f 100644
--- a/drivers/dax/Kconfig
+++ b/drivers/dax/Kconfig
@@ -45,6 +45,19 @@ config DEV_DAX_HMEM
Say M if unsure.
+config DEV_DAX_CXL
+ tristate "CXL DAX: direct access to CXL RAM regions"
+ depends on CXL_REGION && DEV_DAX
+ default CXL_REGION && DEV_DAX
+ help
+ CXL RAM regions are either mapped by platform-firmware
+ and published in the initial system-memory map as "System RAM", mapped
+ by platform-firmware as "Soft Reserved", or dynamically provisioned
+ after boot by the CXL driver. In the latter two cases a device-dax
+ instance is created to access that unmapped-by-default address range.
+ Per usual it can remain as dedicated access via a device interface, or
+ converted to "System RAM" via the dax_kmem facility.
+
config DEV_DAX_HMEM_DEVICES
depends on DEV_DAX_HMEM && DAX
def_bool y
diff --git a/drivers/dax/Makefile b/drivers/dax/Makefile
index 90a56ca3b345468a719c457161bdf1a63de7673a..5ed5c39857c8b4ea85efdde95f8dd7027ea7de20 100644
--- a/drivers/dax/Makefile
+++ b/drivers/dax/Makefile
@@ -3,10 +3,12 @@ obj-$(CONFIG_DAX) += dax.o
obj-$(CONFIG_DEV_DAX) += device_dax.o
obj-$(CONFIG_DEV_DAX_KMEM) += kmem.o
obj-$(CONFIG_DEV_DAX_PMEM) += dax_pmem.o
+obj-$(CONFIG_DEV_DAX_CXL) += dax_cxl.o
dax-y := super.o
dax-y += bus.o
device_dax-y := device.o
dax_pmem-y := pmem.o
+dax_cxl-y := cxl.o
obj-y += hmem/
diff --git a/drivers/dax/cxl.c b/drivers/dax/cxl.c
new file mode 100644
index 0000000000000000000000000000000000000000..ccdf8de85bd5f8b1d9b970a2aca5c81d92f7aebe
--- /dev/null
+++ b/drivers/dax/cxl.c
@@ -0,0 +1,53 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/* Copyright(c) 2023 Intel Corporation. All rights reserved. */
+#include <linux/module.h>
+#include <linux/dax.h>
+
+#include "../cxl/cxl.h"
+#include "bus.h"
+
+static int cxl_dax_region_probe(struct device *dev)
+{
+ struct cxl_dax_region *cxlr_dax = to_cxl_dax_region(dev);
+ int nid = phys_to_target_node(cxlr_dax->hpa_range.start);
+ struct cxl_region *cxlr = cxlr_dax->cxlr;
+ struct dax_region *dax_region;
+ struct dev_dax_data data;
+ struct dev_dax *dev_dax;
+
+ if (nid == NUMA_NO_NODE)
+ nid = memory_add_physaddr_to_nid(cxlr_dax->hpa_range.start);
+
+ dax_region = alloc_dax_region(dev, cxlr->id, &cxlr_dax->hpa_range, nid,
+ PMD_SIZE, IORESOURCE_DAX_KMEM);
+ if (!dax_region)
+ return -ENOMEM;
+
+ data = (struct dev_dax_data) {
+ .dax_region = dax_region,
+ .id = -1,
+ .size = range_len(&cxlr_dax->hpa_range),
+ };
+ dev_dax = devm_create_dev_dax(&data);
+ if (IS_ERR(dev_dax))
+ return PTR_ERR(dev_dax);
+
+ /* child dev_dax instances now own the lifetime of the dax_region */
+ dax_region_put(dax_region);
+ return 0;
+}
+
+static struct cxl_driver cxl_dax_region_driver = {
+ .name = "cxl_dax_region",
+ .probe = cxl_dax_region_probe,
+ .id = CXL_DEVICE_DAX_REGION,
+ .drv = {
+ .suppress_bind_attrs = true,
+ },
+};
+
+module_cxl_driver(cxl_dax_region_driver);
+MODULE_ALIAS_CXL(CXL_DEVICE_DAX_REGION);
+MODULE_LICENSE("GPL");
+MODULE_AUTHOR("Intel Corporation");
+MODULE_IMPORT_NS(CXL);
diff --git a/drivers/dax/hmem/hmem.c b/drivers/dax/hmem/hmem.c
index 5ec08f9f8a57afab92a68ad028647c0614a39327..e5fe8b39fb94beea985cfb0702ec3a6405977385 100644
--- a/drivers/dax/hmem/hmem.c
+++ b/drivers/dax/hmem/hmem.c
@@ -72,6 +72,13 @@ static int hmem_register_device(struct device *host, int target_nid,
long id;
int rc;
+ if (IS_ENABLED(CONFIG_CXL_REGION) &&
+ region_intersects(res->start, resource_size(res), IORESOURCE_MEM,
+ IORES_DESC_CXL) != REGION_DISJOINT) {
+ dev_dbg(host, "deferring range to CXL: %pr\n", res);
+ return 0;
+ }
+
rc = region_intersects(res->start, resource_size(res), IORESOURCE_MEM,
IORES_DESC_SOFT_RESERVED);
if (rc != REGION_INTERSECTS)
@@ -157,6 +164,13 @@ static __exit void dax_hmem_exit(void)
module_init(dax_hmem_init);
module_exit(dax_hmem_exit);
+/* Allow for CXL to define its own dax regions */
+#if IS_ENABLED(CONFIG_CXL_REGION)
+#if IS_MODULE(CONFIG_CXL_ACPI)
+MODULE_SOFTDEP("pre: cxl_acpi");
+#endif
+#endif
+
MODULE_ALIAS("platform:hmem*");
MODULE_ALIAS("platform:hmem_platform*");
MODULE_LICENSE("GPL v2");