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

[Fan Ni <nifan.cxl@gmail.com>]

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