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Date: Tue, 5 Sep 2023 10:55:12 -0700
From: Fan Ni <fan.ni@....us>
To: Jonathan Cameron <Jonathan.Cameron@...wei.com>
Cc: ira.weiny@...el.com, Dan Williams <dan.j.williams@...el.com>,
Navneet Singh <navneet.singh@...el.com>,
Fan Ni <fan.ni@...sung.com>,
Davidlohr Bueso <dave@...olabs.net>,
Dave Jiang <dave.jiang@...el.com>,
Alison Schofield <alison.schofield@...el.com>,
Vishal Verma <vishal.l.verma@...el.com>,
linux-cxl@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH RFC v2 07/18] cxl/mem: Expose device dynamic capacity
configuration
On Tue, Aug 29, 2023 at 04:14:49PM +0100, Jonathan Cameron wrote:
> On Mon, 28 Aug 2023 22:20:58 -0700
> ira.weiny@...el.com wrote:
>
> > From: Navneet Singh <navneet.singh@...el.com>
> >
> > To properly configure CXL regions on Dynamic Capacity Devices (DCD),
> > user space will need to know the details of the DC Regions available on
> > a device.
> >
> > Expose driver dynamic capacity configuration through sysfs
> > attributes.
> >
> > Co-developed-by: Navneet Singh <navneet.singh@...el.com>
> > Signed-off-by: Navneet Singh <navneet.singh@...el.com>
> > Signed-off-by: Ira Weiny <ira.weiny@...el.com>
> >
> One trivial comment inline. I wondered a bit if it would
> be better to not present dc at all on devices that don't support
> dynamic capacity, but for now there isn't an elegant way to do that
> (some discussions and patches are flying around however so maybe this
> will be resolved before this series merges giving us that elegant
> option).
>
> With commented code tidied up
> Reviewed-by: Jonathan Cameron <Jonathan.Cameron@...wei.com>
>
Agreed. It makes more sense to not show dc at all.
Other than that, looks good to me.
Reviewed-by: Fan Ni <fan.ni@...sung.com>
>
> > ---
> > Changes for v2:
> > [iweiny: Rebased on latest master/type2 work]
> > [iweiny: add documentation for sysfs entries]
> > [iweiny: s/dc_regions_count/region_count/]
> > [iweiny: s/dcY_size/regionY_size/]
> > [alison: change size format to %#llx]
> > [iweiny: change count format to %d]
> > [iweiny: Formatting updates]
> > [iweiny: Fix crash when device is not a mem device: found with cxl-test]
> > ---
> > Documentation/ABI/testing/sysfs-bus-cxl | 17 ++++++++
> > drivers/cxl/core/memdev.c | 77 +++++++++++++++++++++++++++++++++
> > 2 files changed, 94 insertions(+)
> >
> > diff --git a/Documentation/ABI/testing/sysfs-bus-cxl b/Documentation/ABI/testing/sysfs-bus-cxl
> > index 2268ffcdb604..aa65dc5b4e13 100644
> > --- a/Documentation/ABI/testing/sysfs-bus-cxl
> > +++ b/Documentation/ABI/testing/sysfs-bus-cxl
> > @@ -37,6 +37,23 @@ Description:
> > identically named field in the Identify Memory Device Output
> > Payload in the CXL-2.0 specification.
> >
> > +What: /sys/bus/cxl/devices/memX/dc/region_count
> > +Date: July, 2023
> > +KernelVersion: v6.6
> > +Contact: linux-cxl@...r.kernel.org
> > +Description:
> > + (RO) Number of Dynamic Capacity (DC) regions supported on the
> > + device. May be 0 if the device does not support Dynamic
> > + Capacity.
> > +
> > +What: /sys/bus/cxl/devices/memX/dc/regionY_size
> > +Date: July, 2023
> > +KernelVersion: v6.6
> > +Contact: linux-cxl@...r.kernel.org
> > +Description:
> > + (RO) Size of the Dynamic Capacity (DC) region Y. Only
> > + available on devices which support DC and only for those
> > + region indexes supported by the device.
> >
> > What: /sys/bus/cxl/devices/memX/serial
> > Date: January, 2022
> > diff --git a/drivers/cxl/core/memdev.c b/drivers/cxl/core/memdev.c
> > index 492486707fd0..397262e0ebd2 100644
> > --- a/drivers/cxl/core/memdev.c
> > +++ b/drivers/cxl/core/memdev.c
> > @@ -101,6 +101,20 @@ static ssize_t pmem_size_show(struct device *dev, struct device_attribute *attr,
> > static struct device_attribute dev_attr_pmem_size =
> > __ATTR(size, 0444, pmem_size_show, NULL);
> >
> > +static ssize_t region_count_show(struct device *dev, struct device_attribute *attr,
> > + char *buf)
> > +{
> > + struct cxl_memdev *cxlmd = to_cxl_memdev(dev);
> > + struct cxl_memdev_state *mds = to_cxl_memdev_state(cxlmd->cxlds);
> > + int len = 0;
> > +
> > + len = sysfs_emit(buf, "%d\n", mds->nr_dc_region);
> > + return len;
>
> return sysfs_emit(buf, "...);
>
> > +}
> > +
> > +struct device_attribute dev_attr_region_count =
> > + __ATTR(region_count, 0444, region_count_show, NULL);
> > +
> > static ssize_t serial_show(struct device *dev, struct device_attribute *attr,
> > char *buf)
> > {
> > @@ -454,6 +468,62 @@ static struct attribute *cxl_memdev_security_attributes[] = {
> > NULL,
> > };
> >
> > +static ssize_t show_size_regionN(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);
> > +}
> > +
> > +#define REGION_SIZE_ATTR_RO(n) \
> > +static ssize_t region##n##_size_show(struct device *dev, \
> > + struct device_attribute *attr, \
> > + char *buf) \
> > +{ \
> > + return show_size_regionN(to_cxl_memdev(dev), buf, (n)); \
> > +} \
> > +static DEVICE_ATTR_RO(region##n##_size)
> > +REGION_SIZE_ATTR_RO(0);
> > +REGION_SIZE_ATTR_RO(1);
> > +REGION_SIZE_ATTR_RO(2);
> > +REGION_SIZE_ATTR_RO(3);
> > +REGION_SIZE_ATTR_RO(4);
> > +REGION_SIZE_ATTR_RO(5);
> > +REGION_SIZE_ATTR_RO(6);
> > +REGION_SIZE_ATTR_RO(7);
> > +
> > +static struct attribute *cxl_memdev_dc_attributes[] = {
> > + &dev_attr_region0_size.attr,
> > + &dev_attr_region1_size.attr,
> > + &dev_attr_region2_size.attr,
> > + &dev_attr_region3_size.attr,
> > + &dev_attr_region4_size.attr,
> > + &dev_attr_region5_size.attr,
> > + &dev_attr_region6_size.attr,
> > + &dev_attr_region7_size.attr,
> > + &dev_attr_region_count.attr,
> > + NULL,
> > +};
> > +
> > +static umode_t cxl_dc_visible(struct kobject *kobj, struct attribute *a, int n)
> > +{
> > + 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;
> > +
> > + if (a == &dev_attr_region_count.attr)
> > + return a->mode;
> > +
> > + if (n < mds->nr_dc_region)
> > + return a->mode;
> > +
> > + return 0;
> > +}
> > +
> > static umode_t cxl_memdev_visible(struct kobject *kobj, struct attribute *a,
> > int n)
> > {
> > @@ -482,11 +552,18 @@ static struct attribute_group cxl_memdev_security_attribute_group = {
> > .attrs = cxl_memdev_security_attributes,
> > };
> >
> > +static struct attribute_group cxl_memdev_dc_attribute_group = {
> > + .name = "dc",
> > + .attrs = cxl_memdev_dc_attributes,
> > + .is_visible = cxl_dc_visible,
> > +};
> > +
> > static const struct attribute_group *cxl_memdev_attribute_groups[] = {
> > &cxl_memdev_attribute_group,
> > &cxl_memdev_ram_attribute_group,
> > &cxl_memdev_pmem_attribute_group,
> > &cxl_memdev_security_attribute_group,
> > + &cxl_memdev_dc_attribute_group,
> > NULL,
> > };
> >
> >
>
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