@@ -47,6 +47,9 @@ CXL Core
CXL Regions
-----------
+.. kernel-doc:: drivers/cxl/region.c
+ :doc: cxl region
+
.. kernel-doc:: drivers/cxl/region.h
:identifiers:
@@ -56,6 +59,9 @@ CXL Regions
.. kernel-doc:: drivers/cxl/core/region.c
:identifiers:
+.. kernel-doc:: drivers/cxl/region.c
+ :identifiers:
+
External Interfaces
===================
@@ -1,6 +1,6 @@
# SPDX-License-Identifier: GPL-2.0
obj-$(CONFIG_CXL_BUS) += core/
-obj-$(CONFIG_CXL_MEM) += cxl_pci.o
+obj-$(CONFIG_CXL_MEM) += cxl_pci.o cxl_region.o
obj-$(CONFIG_CXL_ACPI) += cxl_acpi.o
obj-$(CONFIG_CXL_PMEM) += cxl_pmem.o
@@ -8,3 +8,4 @@ cxl_acpi-y := acpi.o
cxl_pci-y := pci.o
cxl_acpi-y := acpi.o
cxl_pmem-y := pmem.o
+cxl_region-y := region.o
@@ -722,6 +722,8 @@ static int cxl_device_id(struct device *dev)
return CXL_DEVICE_NVDIMM_BRIDGE;
if (dev->type == &cxl_nvdimm_type)
return CXL_DEVICE_NVDIMM;
+ if (is_cxl_region(dev))
+ return CXL_DEVICE_REGION;
return 0;
}
@@ -738,7 +740,18 @@ static int cxl_bus_match(struct device *dev, struct device_driver *drv)
static int cxl_bus_probe(struct device *dev)
{
- return to_cxl_drv(dev->driver)->probe(dev);
+ int id = cxl_device_id(dev);
+
+ if (id == CXL_DEVICE_REGION) {
+ struct cxl_region *region = to_cxl_region(dev);
+
+ if (is_cxl_region_configured(region))
+ return to_cxl_drv(dev->driver)->probe(dev);
+ } else {
+ return to_cxl_drv(dev->driver)->probe(dev);
+ }
+
+ return -ENODEV;
}
static int cxl_bus_remove(struct device *dev)
@@ -18,13 +18,23 @@
* (programming the hardware) is handled by a separate region driver.
*/
-struct cxl_region *to_cxl_region(struct device *dev);
-
-static bool is_region_active(struct cxl_region *region)
+/*
+ * Most sanity checking is left up to region binding. This does the most basic
+ * check to determine whether or not the core should try probing the driver.
+ */
+bool is_cxl_region_configured(struct cxl_region *region)
{
- /* TODO: Regions can't be activated yet. */
- return false;
+ /* zero sized regions aren't a thing. */
+ if (region->requested_size <= 0)
+ return false;
+
+ /* all regions have at least 1 target */
+ if (!region->targets[0])
+ return false;
+
+ return true;
}
+EXPORT_SYMBOL_GPL(is_cxl_region_configured);
static ssize_t offset_show(struct device *dev, struct device_attribute *attr,
char *buf)
@@ -63,7 +73,7 @@ static ssize_t size_store(struct device *dev, struct device_attribute *attr,
return rc;
device_lock(®ion->dev);
- if (is_region_active(region))
+ if (region->active)
rc = -EBUSY;
else
region->requested_size = val;
@@ -91,7 +101,7 @@ static ssize_t uuid_store(struct device *dev, struct device_attribute *attr,
return -EINVAL;
device_lock(®ion->dev);
- if (is_region_active(region))
+ if (region->active)
rc = -EBUSY;
else
rc = uuid_parse(buf, ®ion->uuid);
@@ -318,6 +318,7 @@ extern struct bus_type cxl_bus_type;
enum cxl_driver_id {
CXL_DEVICE_NVDIMM_BRIDGE,
CXL_DEVICE_NVDIMM,
+ CXL_DEVICE_REGION,
};
struct cxl_driver {
@@ -92,4 +92,5 @@ struct cxl_mem {
struct range pmem_range;
struct range ram_range;
};
+
#endif /* __CXL_MEM_H__ */
new file mode 100644
@@ -0,0 +1,100 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/* Copyright(c) 2021 Intel Corporation. All rights reserved. */
+#include <linux/device.h>
+#include <linux/module.h>
+#include "region.h"
+#include "mem.h"
+
+#define CREATE_TRACE_POINTS
+#include "trace.h"
+
+/**
+ * DOC: cxl region
+ *
+ * This module implements a region driver that is capable of programming CXL
+ * hardware to setup regions.
+ *
+ * A CXL region encompasses a chunk of host physical address space that may be
+ * consumed by a single device (x1 interleave aka linear) or across multiple
+ * devices (xN interleaved). A region is a child device of a &struct
+ * cxl_decoder. There may be multiple active regions under a single &struct
+ * cxl_decoder. The common case for multiple regions would be several linear,
+ * contiguous regions under a single decoder. Generally, there will be a 1:1
+ * relationship between decoder and region when the region is interleaved.
+ */
+
+static int bind_region(struct cxl_region *region)
+{
+ int i;
+
+ if (dev_WARN_ONCE(®ion->dev, !is_cxl_region_configured(region),
+ "unconfigured regions can't be probed (race?)\n")) {
+ return -ENXIO;
+ }
+
+ if (region->requested_size % (SZ_256M * region->eniw)) {
+ trace_cxl_region_bind(region, "Invalid size. Must be multiple of NIW");
+ return -ENXIO;
+ }
+
+ for (i = 0; i < region->eniw; i++)
+ if (!region->targets[i]) {
+ trace_cxl_region_bind(region, "Missing memory device target");
+ return -ENXIO;
+ }
+
+ /* TODO: Allocate from decoder's address space */
+
+ /* TODO: program HDM decoders */
+
+ if (uuid_is_null(®ion->uuid))
+ uuid_gen(®ion->uuid);
+
+ trace_cxl_region_bind(region, "Region binding succeeded.");
+ return 0;
+}
+
+static int cxl_region_probe(struct device *dev)
+{
+ struct cxl_region *region = to_cxl_region(dev);
+ int ret;
+
+ device_lock_assert(®ion->dev);
+
+ if (region->active)
+ return -EBUSY;
+
+ ret = bind_region(region);
+ if (!ret)
+ region->active = true;
+
+ return ret;
+}
+
+static void cxl_region_remove(struct device *dev)
+{
+ /* Remove region from the decoder's address space */
+}
+
+static struct cxl_driver cxl_region_driver = {
+ .name = "cxl_region",
+ .probe = cxl_region_probe,
+ .remove = cxl_region_remove,
+ .id = CXL_DEVICE_REGION,
+};
+
+static __init int cxl_region_init(void)
+{
+ return cxl_driver_register(&cxl_region_driver);
+}
+
+static __exit void cxl_region_exit(void)
+{
+ cxl_driver_unregister(&cxl_region_driver);
+}
+
+MODULE_LICENSE("GPL v2");
+module_init(cxl_region_init);
+module_exit(cxl_region_exit);
+MODULE_IMPORT_NS(CXL);
+MODULE_ALIAS_CXL(CXL_REGION);
@@ -14,6 +14,7 @@
* @uuid: The UUID for this region.
* @list: Node in decoders region list.
* @eniw: Number of interleave ways this region is configured for.
+ * @active: If the region has been activated.
* @targets: The memory devices comprising the region.
*/
struct cxl_region {
@@ -24,7 +25,10 @@ struct cxl_region {
uuid_t uuid;
struct list_head list;
int eniw;
+ bool active;
struct cxl_memdev *targets[];
};
+bool is_cxl_region_configured(struct cxl_region *region);
+
#endif
new file mode 100644
@@ -0,0 +1,33 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+
+#undef TRACE_SYSTEM
+#define TRACE_SYSTEM cxl
+
+#if !defined(__CXL_TRACE_H__) || defined(TRACE_HEADER_MULTI_READ)
+#define __CXL_TRACE_H__
+
+#include <linux/tracepoint.h>
+
+TRACE_EVENT(cxl_region_bind,
+ TP_PROTO(struct cxl_region *region, char *status),
+ TP_ARGS(region, status),
+ TP_STRUCT__entry(
+ __field(struct cxl_region *, region)
+ __string(status, status)
+ ),
+
+ TP_fast_assign(
+ __entry->region = region;
+ __assign_str(status, status);
+ ),
+
+ TP_printk("%s failed to bind (%s)", dev_name(&__entry->region->dev), __get_str(status))
+);
+
+#endif /* if !defined (__CXL_TRACE_H__) || defined(TRACE_HEADER_MULTI_READ) */
+
+/* This part must be outside protection */
+#undef TRACE_INCLUDE_PATH
+#define TRACE_INCLUDE_PATH ../../../drivers/cxl
+#define TRACE_INCLUDE_FILE trace
+#include <trace/define_trace.h>
The cxl_region driver is responsible for managing the HDM decoder programming in the CXL topology. Once a region is created it must be configured and bound to the driver in order to activate it. The following is a sample of how such controls might work: echo 1 > /sys/bus/cxl/devices/decoder0.0/create_region echo $((256<<20)) > /sys/bus/cxl/devices/decoder0.0/region0.0:0/size echo mem0 > /sys/bus/cxl/devices/decoder0.0/region0.0:0/target0 echo region0.0:0 > /sys/bus/cxl/drivers/cxl_region/bind In order to handle the eventual rise in failure modes of binding a region, a new trace event is created to help track these failures for debug and reconfiguration paths in userspace. Signed-off-by: Ben Widawsky <ben.widawsky@intel.com> --- .../driver-api/cxl/memory-devices.rst | 6 ++ drivers/cxl/Makefile | 3 +- drivers/cxl/core/bus.c | 15 ++- drivers/cxl/core/region.c | 24 +++-- drivers/cxl/cxl.h | 1 + drivers/cxl/mem.h | 1 + drivers/cxl/region.c | 100 ++++++++++++++++++ drivers/cxl/region.h | 4 + drivers/cxl/trace.h | 33 ++++++ 9 files changed, 178 insertions(+), 9 deletions(-) create mode 100644 drivers/cxl/region.c create mode 100644 drivers/cxl/trace.h