Re: [PATCH v4 13/28] cxl/mem: Expose DCD partition capabilities in sysfs

Fan Ni
2024-10-09T20:46:36Z

On Mon, Oct 07, 2024 at 06:16:19PM -0500, ira.weiny@intel.com wrote:
> From: Navneet Singh <navneet.singh@intel.com>
>
> To properly configure CXL regions on Dynamic Capacity Devices (DCD),
> user space will need to know the details of the DC partitions available.
>
> Expose dynamic capacity capabilities through sysfs.
>
> Signed-off-by: Navneet Singh <navneet.singh@intel.com>
> Co-developed-by: Ira Weiny <ira.weiny@intel.com>
> Signed-off-by: Ira Weiny <ira.weiny@intel.com>
>
> ---
> Changes:
> [iweiny: Change .../memX/dc/* to .../memX/dcY/*]
> [iweiny: add read only and shareable attributes from DSMAS]
> [djiang: Split sysfs docs]
> [iweiny: Adjust sysfs doc dates]
> [iweiny: Add qos details]
> ---
> Documentation/ABI/testing/sysfs-bus-cxl | 45 ++++++++++++
> drivers/cxl/core/memdev.c | 126 ++++++++++++++++++++++++++++++++
> 2 files changed, 171 insertions(+)
>
> diff --git a/Documentation/ABI/testing/sysfs-bus-cxl b/Documentation/ABI/testing/sysfs-bus-cxl
> index 3f5627a1210a..b865eefdb74c 100644
> --- a/Documentation/ABI/testing/sysfs-bus-cxl
> +++ b/Documentation/ABI/testing/sysfs-bus-cxl
> @@ -54,6 +54,51 @@ Description:
> identically named field in the Identify Memory Device Output
> Payload in the CXL-2.0 specification.
>
> +What: /sys/bus/cxl/devices/memX/dcY/size
> +Date: December, 2024
> +KernelVersion: v6.13
> +Contact: linux-cxl@vger.kernel.org
> +Description:
> + (RO) Dynamic Capacity (DC) region information. Devices only
> + export dcY if DCD partition Y is supported.
> + dcY/size is the size of each of those partitions.
> +
> +What: /sys/bus/cxl/devices/memX/dcY/read_only
> +Date: December, 2024
> +KernelVersion: v6.13
> +Contact: linux-cxl@vger.kernel.org
> +Description:
> + (RO) Dynamic Capacity (DC) region information. Devices only
> + export dcY if DCD partition Y is supported.
> + dcY/read_only indicates true if the region is exported
> + read_only from the device.
> +
> +What: /sys/bus/cxl/devices/memX/dcY/shareable
> +Date: December, 2024
> +KernelVersion: v6.13
> +Contact: linux-cxl@vger.kernel.org
> +Description:
> + (RO) Dynamic Capacity (DC) region information. Devices only
> + export dcY if DCD partition Y is supported.
> + dcY/shareable indicates true if the region is exported
> + shareable from the device.
> +
> +What: /sys/bus/cxl/devices/memX/dcY/qos_class
> +Date: December, 2024
> +KernelVersion: v6.13
> +Contact: linux-cxl@vger.kernel.org
> +Description:
> + (RO) Dynamic Capacity (DC) region information. Devices only
> + export dcY if DCD partition Y is supported. For CXL host
> + platforms that support "QoS Telemmetry" this attribute conveys
> + a comma delimited list of platform specific cookies that
> + identifies a QoS performance class for the persistent partition
> + of the CXL mem device. These class-ids can be compared against
> + a similar "qos_class" published for a root decoder. While it is
> + not required that the endpoints map their local memory-class to
> + a matching platform class, mismatches are not recommended and
> + there are platform specific performance related side-effects
> + that may result. First class-id is displayed.
>
> What: /sys/bus/cxl/devices/memX/pmem/qos_class
> Date: May, 2023
> diff --git a/drivers/cxl/core/memdev.c b/drivers/cxl/core/memdev.c
> index 84fefb76dafa..2565b10a769c 100644
> --- a/drivers/cxl/core/memdev.c
> +++ b/drivers/cxl/core/memdev.c
> @@ -2,6 +2,7 @@
> /* Copyright(c) 2020 Intel Corporation. */
>
> #include <linux/io-64-nonatomic-lo-hi.h>
> +#include <linux/string_choices.h>
> #include <linux/firmware.h>
> #include <linux/device.h>
> #include <linux/slab.h>
> @@ -449,6 +450,123 @@ static struct attribute *cxl_memdev_security_attributes[] = {
> NULL,
> };
>
> +static ssize_t show_size_dcN(struct cxl_memdev *cxlmd, char *buf, int pos)
> +{
> + struct cxl_memdev_state *mds = to_cxl_memdev_state(cxlmd->cxlds);
> +
> + return sysfs_emit(buf, "%#llx\n", mds->dc_region[pos].decode_len);
> +}
> +
> +static ssize_t show_read_only_dcN(struct cxl_memdev *cxlmd, char *buf, int pos)
> +{
> + struct cxl_memdev_state *mds = to_cxl_memdev_state(cxlmd->cxlds);
> +
> + return sysfs_emit(buf, "%s\n",
> + str_false_true(mds->dc_region[pos].read_only));

For this function and below, why str_false_true instead of
str_true_false??

Fan
> +}
> +
> +static ssize_t show_shareable_dcN(struct cxl_memdev *cxlmd, char *buf, int pos)
> +{
> + struct cxl_memdev_state *mds = to_cxl_memdev_state(cxlmd->cxlds);
> +
> + return sysfs_emit(buf, "%s\n",
> + str_false_true(mds->dc_region[pos].shareable));
> +}
> +
> +static ssize_t show_qos_class_dcN(struct cxl_memdev *cxlmd, char *buf, int pos)
> +{
> + struct cxl_memdev_state *mds = to_cxl_memdev_state(cxlmd->cxlds);
> +
> + return sysfs_emit(buf, "%d\n", mds->dc_perf[pos].qos_class);
> +}
> +
> +#define CXL_MEMDEV_DC_ATTR_GROUP(n) \
> +static ssize_t dc##n##_size_show(struct device *dev, \
> + struct device_attribute *attr, \
> + char *buf) \
> +{ \
> + return show_size_dcN(to_cxl_memdev(dev), buf, (n)); \
> +} \
> +struct device_attribute dc##n##_size = { \
> + .attr = { .name = "size", .mode = 0444 }, \
> + .show = dc##n##_size_show, \
> +}; \
> +static ssize_t dc##n##_read_only_show(struct device *dev, \
> + struct device_attribute *attr, \
> + char *buf) \
> +{ \
> + return show_read_only_dcN(to_cxl_memdev(dev), buf, (n)); \
> +} \
> +struct device_attribute dc##n##_read_only = { \
> + .attr = { .name = "read_only", .mode = 0444 }, \
> + .show = dc##n##_read_only_show, \
> +}; \
> +static ssize_t dc##n##_shareable_show(struct device *dev, \
> + struct device_attribute *attr, \
> + char *buf) \
> +{ \
> + return show_shareable_dcN(to_cxl_memdev(dev), buf, (n)); \
> +} \
> +struct device_attribute dc##n##_shareable = { \
> + .attr = { .name = "shareable", .mode = 0444 }, \
> + .show = dc##n##_shareable_show, \
> +}; \
> +static ssize_t dc##n##_qos_class_show(struct device *dev, \
> + struct device_attribute *attr, \
> + char *buf) \
> +{ \
> + return show_qos_class_dcN(to_cxl_memdev(dev), buf, (n)); \
> +} \
> +struct device_attribute dc##n##_qos_class = { \
> + .attr = { .name = "qos_class", .mode = 0444 }, \
> + .show = dc##n##_qos_class_show, \
> +}; \
> +static struct attribute *cxl_memdev_dc##n##_attributes[] = { \
> + &dc##n##_size.attr, \
> + &dc##n##_read_only.attr, \
> + &dc##n##_shareable.attr, \
> + &dc##n##_qos_class.attr, \
> + NULL, \
> +}; \
> +static umode_t cxl_memdev_dc##n##_attr_visible(struct kobject *kobj, \
> + struct attribute *a, \
> + int pos) \
> +{ \
> + struct device *dev = kobj_to_dev(kobj); \
> + struct cxl_memdev *cxlmd = to_cxl_memdev(dev); \
> + struct cxl_memdev_state *mds = to_cxl_memdev_state(cxlmd->cxlds); \
> + \
> + /* Not a memory device */ \
> + if (!mds) \
> + return 0; \
> + return a->mode; \
> +} \
> +static umode_t cxl_memdev_dc##n##_group_visible(struct kobject *kobj) \
> +{ \
> + struct device *dev = kobj_to_dev(kobj); \
> + struct cxl_memdev *cxlmd = to_cxl_memdev(dev); \
> + struct cxl_memdev_state *mds = to_cxl_memdev_state(cxlmd->cxlds); \
> + \
> + /* Not a memory device or partition not supported */ \
> + if (!mds || n >= mds->nr_dc_region) \
> + return false; \
> + return true; \
> +} \
> +DEFINE_SYSFS_GROUP_VISIBLE(cxl_memdev_dc##n); \
> +static struct attribute_group cxl_memdev_dc##n##_group = { \
> + .name = "dc"#n, \
> + .attrs = cxl_memdev_dc##n##_attributes, \
> + .is_visible = SYSFS_GROUP_VISIBLE(cxl_memdev_dc##n), \
> +}
> +CXL_MEMDEV_DC_ATTR_GROUP(0);
> +CXL_MEMDEV_DC_ATTR_GROUP(1);
> +CXL_MEMDEV_DC_ATTR_GROUP(2);
> +CXL_MEMDEV_DC_ATTR_GROUP(3);
> +CXL_MEMDEV_DC_ATTR_GROUP(4);
> +CXL_MEMDEV_DC_ATTR_GROUP(5);
> +CXL_MEMDEV_DC_ATTR_GROUP(6);
> +CXL_MEMDEV_DC_ATTR_GROUP(7);
> +
> static umode_t cxl_memdev_visible(struct kobject *kobj, struct attribute *a,
> int n)
> {
> @@ -525,6 +643,14 @@ static struct attribute_group cxl_memdev_security_attribute_group = {
> };
>
> static const struct attribute_group *cxl_memdev_attribute_groups[] = {
> + &cxl_memdev_dc0_group,
> + &cxl_memdev_dc1_group,
> + &cxl_memdev_dc2_group,
> + &cxl_memdev_dc3_group,
> + &cxl_memdev_dc4_group,
> + &cxl_memdev_dc5_group,
> + &cxl_memdev_dc6_group,
> + &cxl_memdev_dc7_group,
> &cxl_memdev_attribute_group,
> &cxl_memdev_ram_attribute_group,
> &cxl_memdev_pmem_attribute_group,
>
> --
> 2.46.0
>

--
Fan Ni