| Message ID | 20220624041950.559155-10-dan.j.williams@intel.com (mailing list archive) |
|---|---|
| State | Superseded |
| Headers | show |
| Series | CXL PMEM Region Provisioning | expand |
On Thu, 23 Jun 2022 21:19:39 -0700 Dan Williams <dan.j.williams@intel.com> wrote: > From: Ben Widawsky <bwidawsk@kernel.org> > > The process of provisioning a region involves triggering the creation of > a new region object, pouring in the configuration, and then binding that > configured object to the region driver to start is operation. For > persistent memory regions the CXL specification mandates that it > identified by a uuid. Add an ABI for userspace to specify a region's > uuid. > > Signed-off-by: Ben Widawsky <bwidawsk@kernel.org> > [djbw: simplify locking] > Signed-off-by: Dan Williams <dan.j.williams@intel.com> I think this needs to be a little less restrictive as it currently errors out on trying to write the same UUID to the same region twice. Short cut that case and just return 0 if the UUID is same as already set. Thanks, Jonathan > --- > Documentation/ABI/testing/sysfs-bus-cxl | 10 +++ > drivers/cxl/core/region.c | 115 ++++++++++++++++++++++++ > drivers/cxl/cxl.h | 25 ++++++ > 3 files changed, 150 insertions(+) > > diff --git a/Documentation/ABI/testing/sysfs-bus-cxl b/Documentation/ABI/testing/sysfs-bus-cxl > index 9a4856066631..d30c95a758a9 100644 > --- a/Documentation/ABI/testing/sysfs-bus-cxl > +++ b/Documentation/ABI/testing/sysfs-bus-cxl > @@ -263,3 +263,13 @@ Contact: linux-cxl@vger.kernel.org > Description: > (WO) Write a string in the form 'regionZ' to delete that region, > provided it is currently idle / not bound to a driver. > + > + > +What: /sys/bus/cxl/devices/regionZ/uuid > +Date: May, 2022 > +KernelVersion: v5.20 > +Contact: linux-cxl@vger.kernel.org > +Description: > + (RW) Write a unique identifier for the region. This field must > + be set for persistent regions and it must not conflict with the > + UUID of another region. > diff --git a/drivers/cxl/core/region.c b/drivers/cxl/core/region.c > index f2a0ead20ca7..f75978f846b9 100644 > --- a/drivers/cxl/core/region.c > +++ b/drivers/cxl/core/region.c > @@ -5,6 +5,7 @@ > #include <linux/device.h> > #include <linux/module.h> > #include <linux/slab.h> > +#include <linux/uuid.h> > #include <linux/idr.h> > #include <cxl.h> > #include "core.h" > @@ -17,10 +18,123 @@ > * Memory ranges, Regions represent the active mapped capacity by the HDM > * Decoder Capability structures throughout the Host Bridges, Switches, and > * Endpoints in the topology. > + * > + * Region configuration has ordering constraints. UUID may be set at any time > + * but is only visible for persistent regions. > + */ > + > +/* > + * All changes to the interleave configuration occur with this lock held > + * for write. > */ > +static DECLARE_RWSEM(cxl_region_rwsem); > > static struct cxl_region *to_cxl_region(struct device *dev); > > +static ssize_t uuid_show(struct device *dev, struct device_attribute *attr, > + char *buf) > +{ > + struct cxl_region *cxlr = to_cxl_region(dev); > + struct cxl_region_params *p = &cxlr->params; > + ssize_t rc; > + > + rc = down_read_interruptible(&cxl_region_rwsem); > + if (rc) > + return rc; > + rc = sysfs_emit(buf, "%pUb\n", &p->uuid); > + up_read(&cxl_region_rwsem); > + > + return rc; > +} > + > +static int is_dup(struct device *match, void *data) > +{ > + struct cxl_region_params *p; > + struct cxl_region *cxlr; > + uuid_t *uuid = data; > + > + if (!is_cxl_region(match)) > + return 0; > + > + lockdep_assert_held(&cxl_region_rwsem); > + cxlr = to_cxl_region(match); > + p = &cxlr->params; > + > + if (uuid_equal(&p->uuid, uuid)) { > + dev_dbg(match, "already has uuid: %pUb\n", uuid); > + return -EBUSY; > + } > + > + return 0; > +} > + > +static ssize_t uuid_store(struct device *dev, struct device_attribute *attr, > + const char *buf, size_t len) > +{ > + struct cxl_region *cxlr = to_cxl_region(dev); > + struct cxl_region_params *p = &cxlr->params; > + uuid_t temp; > + ssize_t rc; > + > + if (len != UUID_STRING_LEN + 1) > + return -EINVAL; > + > + rc = uuid_parse(buf, &temp); > + if (rc) > + return rc; > + > + if (uuid_is_null(&temp)) > + return -EINVAL; > + > + rc = down_write_killable(&cxl_region_rwsem); > + if (rc) > + return rc; > + > + rc = -EBUSY; > + if (p->state >= CXL_CONFIG_ACTIVE) > + goto out; > + > + rc = bus_for_each_dev(&cxl_bus_type, NULL, &temp, is_dup); > + if (rc < 0) > + goto out; > + > + uuid_copy(&p->uuid, &temp); > +out: > + up_write(&cxl_region_rwsem); > + > + if (rc) > + return rc; > + return len; > +} > +static DEVICE_ATTR_RW(uuid); > + > +static umode_t cxl_region_visible(struct kobject *kobj, struct attribute *a, > + int n) > +{ > + struct device *dev = kobj_to_dev(kobj); > + struct cxl_region *cxlr = to_cxl_region(dev); > + > + if (a == &dev_attr_uuid.attr && cxlr->mode != CXL_DECODER_PMEM) > + return 0; > + return a->mode; > +} > + > +static struct attribute *cxl_region_attrs[] = { > + &dev_attr_uuid.attr, > + NULL, > +}; > + > +static const struct attribute_group cxl_region_group = { > + .attrs = cxl_region_attrs, > + .is_visible = cxl_region_visible, > +}; > + > +static const struct attribute_group *region_groups[] = { > + &cxl_base_attribute_group, > + &cxl_region_group, > + NULL, > +}; > + > static void cxl_region_release(struct device *dev) > { > struct cxl_region *cxlr = to_cxl_region(dev); > @@ -32,6 +146,7 @@ static void cxl_region_release(struct device *dev) > static const struct device_type cxl_region_type = { > .name = "cxl_region", > .release = cxl_region_release, > + .groups = region_groups > }; > > bool is_cxl_region(struct device *dev) > diff --git a/drivers/cxl/cxl.h b/drivers/cxl/cxl.h > index 49b73b2e44a9..46a9f8acc602 100644 > --- a/drivers/cxl/cxl.h > +++ b/drivers/cxl/cxl.h > @@ -288,18 +288,43 @@ struct cxl_root_decoder { > struct cxl_switch_decoder cxlsd; > }; > > +/* > + * enum cxl_config_state - State machine for region configuration > + * @CXL_CONFIG_IDLE: Any sysfs attribute can be written freely > + * @CXL_CONFIG_ACTIVE: All targets have been added the region is now > + * active > + */ > +enum cxl_config_state { > + CXL_CONFIG_IDLE, > + CXL_CONFIG_ACTIVE, > +}; > + > +/** > + * struct cxl_region_params - region settings > + * @state: allow the driver to lockdown further parameter changes > + * @uuid: unique id for persistent regions > + * > + * State transitions are protected by the cxl_region_rwsem > + */ > +struct cxl_region_params { > + enum cxl_config_state state; > + uuid_t uuid; > +}; > + > /** > * struct cxl_region - CXL region > * @dev: This region's device > * @id: This region's id. Id is globally unique across all regions > * @mode: Endpoint decoder allocation / access mode > * @type: Endpoint decoder target type > + * @params: active + config params for the region > */ > struct cxl_region { > struct device dev; > int id; > enum cxl_decoder_mode mode; > enum cxl_decoder_type type; > + struct cxl_region_params params; > }; > > /**
Jonathan Cameron wrote: > On Thu, 23 Jun 2022 21:19:39 -0700 > Dan Williams <dan.j.williams@intel.com> wrote: > > > From: Ben Widawsky <bwidawsk@kernel.org> > > > > The process of provisioning a region involves triggering the creation of > > a new region object, pouring in the configuration, and then binding that > > configured object to the region driver to start is operation. For > > persistent memory regions the CXL specification mandates that it > > identified by a uuid. Add an ABI for userspace to specify a region's > > uuid. > > > > Signed-off-by: Ben Widawsky <bwidawsk@kernel.org> > > [djbw: simplify locking] > > Signed-off-by: Dan Williams <dan.j.williams@intel.com> > > I think this needs to be a little less restrictive as it currently errors > out on trying to write the same UUID to the same region twice. > > Short cut that case and just return 0 if the UUID is same as already set. Sure, fixed that up locally.
diff --git a/Documentation/ABI/testing/sysfs-bus-cxl b/Documentation/ABI/testing/sysfs-bus-cxl index 9a4856066631..d30c95a758a9 100644 --- a/Documentation/ABI/testing/sysfs-bus-cxl +++ b/Documentation/ABI/testing/sysfs-bus-cxl @@ -263,3 +263,13 @@ Contact: linux-cxl@vger.kernel.org Description: (WO) Write a string in the form 'regionZ' to delete that region, provided it is currently idle / not bound to a driver. + + +What: /sys/bus/cxl/devices/regionZ/uuid +Date: May, 2022 +KernelVersion: v5.20 +Contact: linux-cxl@vger.kernel.org +Description: + (RW) Write a unique identifier for the region. This field must + be set for persistent regions and it must not conflict with the + UUID of another region. diff --git a/drivers/cxl/core/region.c b/drivers/cxl/core/region.c index f2a0ead20ca7..f75978f846b9 100644 --- a/drivers/cxl/core/region.c +++ b/drivers/cxl/core/region.c @@ -5,6 +5,7 @@ #include <linux/device.h> #include <linux/module.h> #include <linux/slab.h> +#include <linux/uuid.h> #include <linux/idr.h> #include <cxl.h> #include "core.h" @@ -17,10 +18,123 @@ * Memory ranges, Regions represent the active mapped capacity by the HDM * Decoder Capability structures throughout the Host Bridges, Switches, and * Endpoints in the topology. + * + * Region configuration has ordering constraints. UUID may be set at any time + * but is only visible for persistent regions. + */ + +/* + * All changes to the interleave configuration occur with this lock held + * for write. */ +static DECLARE_RWSEM(cxl_region_rwsem); static struct cxl_region *to_cxl_region(struct device *dev); +static ssize_t uuid_show(struct device *dev, struct device_attribute *attr, + char *buf) +{ + struct cxl_region *cxlr = to_cxl_region(dev); + struct cxl_region_params *p = &cxlr->params; + ssize_t rc; + + rc = down_read_interruptible(&cxl_region_rwsem); + if (rc) + return rc; + rc = sysfs_emit(buf, "%pUb\n", &p->uuid); + up_read(&cxl_region_rwsem); + + return rc; +} + +static int is_dup(struct device *match, void *data) +{ + struct cxl_region_params *p; + struct cxl_region *cxlr; + uuid_t *uuid = data; + + if (!is_cxl_region(match)) + return 0; + + lockdep_assert_held(&cxl_region_rwsem); + cxlr = to_cxl_region(match); + p = &cxlr->params; + + if (uuid_equal(&p->uuid, uuid)) { + dev_dbg(match, "already has uuid: %pUb\n", uuid); + return -EBUSY; + } + + return 0; +} + +static ssize_t uuid_store(struct device *dev, struct device_attribute *attr, + const char *buf, size_t len) +{ + struct cxl_region *cxlr = to_cxl_region(dev); + struct cxl_region_params *p = &cxlr->params; + uuid_t temp; + ssize_t rc; + + if (len != UUID_STRING_LEN + 1) + return -EINVAL; + + rc = uuid_parse(buf, &temp); + if (rc) + return rc; + + if (uuid_is_null(&temp)) + return -EINVAL; + + rc = down_write_killable(&cxl_region_rwsem); + if (rc) + return rc; + + rc = -EBUSY; + if (p->state >= CXL_CONFIG_ACTIVE) + goto out; + + rc = bus_for_each_dev(&cxl_bus_type, NULL, &temp, is_dup); + if (rc < 0) + goto out; + + uuid_copy(&p->uuid, &temp); +out: + up_write(&cxl_region_rwsem); + + if (rc) + return rc; + return len; +} +static DEVICE_ATTR_RW(uuid); + +static umode_t cxl_region_visible(struct kobject *kobj, struct attribute *a, + int n) +{ + struct device *dev = kobj_to_dev(kobj); + struct cxl_region *cxlr = to_cxl_region(dev); + + if (a == &dev_attr_uuid.attr && cxlr->mode != CXL_DECODER_PMEM) + return 0; + return a->mode; +} + +static struct attribute *cxl_region_attrs[] = { + &dev_attr_uuid.attr, + NULL, +}; + +static const struct attribute_group cxl_region_group = { + .attrs = cxl_region_attrs, + .is_visible = cxl_region_visible, +}; + +static const struct attribute_group *region_groups[] = { + &cxl_base_attribute_group, + &cxl_region_group, + NULL, +}; + static void cxl_region_release(struct device *dev) { struct cxl_region *cxlr = to_cxl_region(dev); @@ -32,6 +146,7 @@ static void cxl_region_release(struct device *dev) static const struct device_type cxl_region_type = { .name = "cxl_region", .release = cxl_region_release, + .groups = region_groups }; bool is_cxl_region(struct device *dev) diff --git a/drivers/cxl/cxl.h b/drivers/cxl/cxl.h index 49b73b2e44a9..46a9f8acc602 100644 --- a/drivers/cxl/cxl.h +++ b/drivers/cxl/cxl.h @@ -288,18 +288,43 @@ struct cxl_root_decoder { struct cxl_switch_decoder cxlsd; }; +/* + * enum cxl_config_state - State machine for region configuration + * @CXL_CONFIG_IDLE: Any sysfs attribute can be written freely + * @CXL_CONFIG_ACTIVE: All targets have been added the region is now + * active + */ +enum cxl_config_state { + CXL_CONFIG_IDLE, + CXL_CONFIG_ACTIVE, +}; + +/** + * struct cxl_region_params - region settings + * @state: allow the driver to lockdown further parameter changes + * @uuid: unique id for persistent regions + * + * State transitions are protected by the cxl_region_rwsem + */ +struct cxl_region_params { + enum cxl_config_state state; + uuid_t uuid; +}; + /** * struct cxl_region - CXL region * @dev: This region's device * @id: This region's id. Id is globally unique across all regions * @mode: Endpoint decoder allocation / access mode * @type: Endpoint decoder target type + * @params: active + config params for the region */ struct cxl_region { struct device dev; int id; enum cxl_decoder_mode mode; enum cxl_decoder_type type; + struct cxl_region_params params; }; /**