On Mon, Mar 27, 2023 at 02:46:06PM -0700, Dave Jiang wrote: > Export qtg_id sysfs attributes for the CXL memory device. The QTG ID > should show up as /sys/bus/cxl/devices/memX/qtg_id. The QTG ID is > retrieved via _DSM after supplying the caluclated bandwidth and latency calculated > for the entire CXL path from device to the CPU. This ID is used to match > up to the root decoder QTG ID to determine which CFMWS the memory range > of a hotplugged CXL mem device should be assigned under. > > While there may be multiple DSMAS exported by the device CDAT, the driver > will only expose the first QTG ID in sysfs for now. In the future when > multiple QTG IDs are necessary, they can be exposed. [1] > > [1]: https://lore.kernel.org/linux-cxl/167571650007.587790.10040913293130712882.stgit@djiang5-mobl3.local/T/#md2a47b1ead3e1ba08f50eab29a4af1aed1d215ab > > Suggested-by: Dan Williams <dan.j.williams@xxxxxxxxx> > Signed-off-by: Dave Jiang <dave.jiang@xxxxxxxxx> > --- > Documentation/ABI/testing/sysfs-bus-cxl | 11 +++++++++++ > drivers/cxl/core/memdev.c | 15 +++++++++++++++ > 2 files changed, 26 insertions(+) > > diff --git a/Documentation/ABI/testing/sysfs-bus-cxl b/Documentation/ABI/testing/sysfs-bus-cxl > index 471ac9a37078..a018f0a21aca 100644 > --- a/Documentation/ABI/testing/sysfs-bus-cxl > +++ b/Documentation/ABI/testing/sysfs-bus-cxl > @@ -58,6 +58,17 @@ Description: > affinity for this device. > > > +What: /sys/bus/cxl/devices/memX/qtg_id > +Date: March, 2024 > +KernelVersion: v6.4 > +Contact: linux-cxl@xxxxxxxxxxxxxxx > +Description: > + (RO) Show the first QoS Throttling Group ID for the device. > + The ID is used to match against the CFMWS (root decoder) > + QTG ID so that the memory range under a hot-plugged device > + is assigned under the appropriate CFMWS. Some of the language in the cover letter seemed more descriptive, but I guess it's a bit squishy to me. (ie. 'some guidance' and 'appropriate') Would a spec link be useful here? Alison > + > + > What: /sys/bus/cxl/devices/*/devtype > Date: June, 2021 > KernelVersion: v5.14 > diff --git a/drivers/cxl/core/memdev.c b/drivers/cxl/core/memdev.c > index d2605fc39240..974eff833edd 100644 > --- a/drivers/cxl/core/memdev.c > +++ b/drivers/cxl/core/memdev.c > @@ -106,12 +106,27 @@ static ssize_t numa_node_show(struct device *dev, struct device_attribute *attr, > } > static DEVICE_ATTR_RO(numa_node); > > +static ssize_t qtg_id_show(struct device *dev, struct device_attribute *attr, > + char *buf) > +{ > + struct cxl_memdev *cxlmd = to_cxl_memdev(dev); > + struct qos_prop_entry *qos; > + > + if (list_empty(&cxlmd->qos_list)) > + return 0; > + > + qos = list_first_entry(&cxlmd->qos_list, struct qos_prop_entry, list); > + return sysfs_emit(buf, "%u\n", qos->qtg_id); > +} > +static DEVICE_ATTR_RO(qtg_id); > + > static struct attribute *cxl_memdev_attributes[] = { > &dev_attr_serial.attr, > &dev_attr_firmware_version.attr, > &dev_attr_payload_max.attr, > &dev_attr_label_storage_size.attr, > &dev_attr_numa_node.attr, > + &dev_attr_qtg_id.attr, > NULL, > }; > > >
