From: Ben Widawsky <bwidawsk@xxxxxxxxxx> Add ABI to allow the number of devices that comprise a region to be set as well as the interleave granularity for the region. Signed-off-by: Ben Widawsky <bwidawsk@xxxxxxxxxx> [djbw: reword changelog] Reviewed-by: Jonathan Cameron <Jonathan.Cameron@xxxxxxxxxx> Link: https://lore.kernel.org/r/20220624041950.559155-11-dan.j.williams@xxxxxxxxx Signed-off-by: Dan Williams <dan.j.williams@xxxxxxxxx> --- Documentation/ABI/testing/sysfs-bus-cxl | 21 +++++ drivers/cxl/core/region.c | 128 +++++++++++++++++++++++++++++++ drivers/cxl/cxl.h | 33 ++++++++ 3 files changed, 182 insertions(+) diff --git a/Documentation/ABI/testing/sysfs-bus-cxl b/Documentation/ABI/testing/sysfs-bus-cxl index 0760b8402c23..bfa42bcc8383 100644 --- a/Documentation/ABI/testing/sysfs-bus-cxl +++ b/Documentation/ABI/testing/sysfs-bus-cxl @@ -292,3 +292,24 @@ 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. + + +What: /sys/bus/cxl/devices/regionZ/interleave_granularity +Date: May, 2022 +KernelVersion: v5.20 +Contact: linux-cxl@xxxxxxxxxxxxxxx +Description: + (RW) Set the number of consecutive bytes each device in the + interleave set will claim. The possible interleave granularity + values are determined by the CXL spec and the participating + devices. + + +What: /sys/bus/cxl/devices/regionZ/interleave_ways +Date: May, 2022 +KernelVersion: v5.20 +Contact: linux-cxl@xxxxxxxxxxxxxxx +Description: + (RW) Configures the number of devices participating in the + region is set by writing this value. Each device will provide + 1/interleave_ways of storage for the region. diff --git a/drivers/cxl/core/region.c b/drivers/cxl/core/region.c index 22dccb4702e5..3289caa5d882 100644 --- a/drivers/cxl/core/region.c +++ b/drivers/cxl/core/region.c @@ -7,6 +7,7 @@ #include <linux/slab.h> #include <linux/uuid.h> #include <linux/idr.h> +#include <cxlmem.h> #include <cxl.h> #include "core.h" @@ -21,6 +22,8 @@ * * Region configuration has ordering constraints. UUID may be set at any time * but is only visible for persistent regions. + * 1. Interleave granularity + * 2. Interleave size */ /* @@ -122,8 +125,129 @@ static umode_t cxl_region_visible(struct kobject *kobj, struct attribute *a, return a->mode; } +static ssize_t interleave_ways_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, "%d\n", p->interleave_ways); + up_read(&cxl_region_rwsem); + + return rc; +} + +static ssize_t interleave_ways_store(struct device *dev, + struct device_attribute *attr, + const char *buf, size_t len) +{ + struct cxl_root_decoder *cxlrd = to_cxl_root_decoder(dev->parent); + struct cxl_decoder *cxld = &cxlrd->cxlsd.cxld; + struct cxl_region *cxlr = to_cxl_region(dev); + struct cxl_region_params *p = &cxlr->params; + int rc, val; + u8 iw; + + rc = kstrtoint(buf, 0, &val); + if (rc) + return rc; + + rc = ways_to_cxl(val, &iw); + if (rc) + return rc; + + /* + * Even for x3, x9, and x12 interleaves the region interleave must be a + * power of 2 multiple of the host bridge interleave. + */ + if (!is_power_of_2(val / cxld->interleave_ways) || + (val % cxld->interleave_ways)) { + dev_dbg(&cxlr->dev, "invalid interleave: %d\n", val); + return -EINVAL; + } + + rc = down_write_killable(&cxl_region_rwsem); + if (rc) + return rc; + if (p->state >= CXL_CONFIG_INTERLEAVE_ACTIVE) { + rc = -EBUSY; + goto out; + } + + p->interleave_ways = val; +out: + up_write(&cxl_region_rwsem); + if (rc) + return rc; + return len; +} +static DEVICE_ATTR_RW(interleave_ways); + +static ssize_t interleave_granularity_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, "%d\n", p->interleave_granularity); + up_read(&cxl_region_rwsem); + + return rc; +} + +static ssize_t interleave_granularity_store(struct device *dev, + struct device_attribute *attr, + const char *buf, size_t len) +{ + struct cxl_root_decoder *cxlrd = to_cxl_root_decoder(dev->parent); + struct cxl_decoder *cxld = &cxlrd->cxlsd.cxld; + struct cxl_region *cxlr = to_cxl_region(dev); + struct cxl_region_params *p = &cxlr->params; + int rc, val; + u16 ig; + + rc = kstrtoint(buf, 0, &val); + if (rc) + return rc; + + rc = granularity_to_cxl(val, &ig); + if (rc) + return rc; + + /* region granularity must be >= root granularity */ + if (val < cxld->interleave_granularity) + return -EINVAL; + + rc = down_write_killable(&cxl_region_rwsem); + if (rc) + return rc; + if (p->state >= CXL_CONFIG_INTERLEAVE_ACTIVE) { + rc = -EBUSY; + goto out; + } + + p->interleave_granularity = val; +out: + up_write(&cxl_region_rwsem); + if (rc) + return rc; + return len; +} +static DEVICE_ATTR_RW(interleave_granularity); + static struct attribute *cxl_region_attrs[] = { &dev_attr_uuid.attr, + &dev_attr_interleave_ways.attr, + &dev_attr_interleave_granularity.attr, NULL, }; @@ -216,6 +340,8 @@ static struct cxl_region *devm_cxl_add_region(struct cxl_root_decoder *cxlrd, enum cxl_decoder_type type) { struct cxl_port *port = to_cxl_port(cxlrd->cxlsd.cxld.dev.parent); + struct cxl_decoder *cxld = &cxlrd->cxlsd.cxld; + struct cxl_region_params *p; struct cxl_region *cxlr; struct device *dev; int rc; @@ -223,8 +349,10 @@ static struct cxl_region *devm_cxl_add_region(struct cxl_root_decoder *cxlrd, cxlr = cxl_region_alloc(cxlrd, id); if (IS_ERR(cxlr)) return cxlr; + p = &cxlr->params; cxlr->mode = mode; cxlr->type = type; + p->interleave_granularity = cxld->interleave_granularity; dev = &cxlr->dev; rc = dev_set_name(dev, "region%d", id); diff --git a/drivers/cxl/cxl.h b/drivers/cxl/cxl.h index cf2ece363015..a4e65c102bed 100644 --- a/drivers/cxl/cxl.h +++ b/drivers/cxl/cxl.h @@ -7,6 +7,7 @@ #include <linux/libnvdimm.h> #include <linux/bitfield.h> #include <linux/bitops.h> +#include <linux/log2.h> #include <linux/io.h> /** @@ -92,6 +93,31 @@ static inline int cxl_to_ways(u8 eniw, unsigned int *val) return 0; } +static inline int granularity_to_cxl(int g, u16 *ig) +{ + if (g > SZ_16K || g < 256 || !is_power_of_2(g)) + return -EINVAL; + *ig = ilog2(g) - 8; + return 0; +} + +static inline int ways_to_cxl(int ways, u8 *iw) +{ + if (ways > 16) + return -EINVAL; + if (is_power_of_2(ways)) { + *iw = ilog2(ways); + return 0; + } + if (ways % 3) + return -EINVAL; + ways /= 3; + if (!is_power_of_2(ways)) + return -EINVAL; + *iw = ilog2(ways) + 8; + return 0; +} + /* CXL 2.0 8.2.8.1 Device Capabilities Array Register */ #define CXLDEV_CAP_ARRAY_OFFSET 0x0 #define CXLDEV_CAP_ARRAY_CAP_ID 0 @@ -298,11 +324,14 @@ struct cxl_root_decoder { /* * enum cxl_config_state - State machine for region configuration * @CXL_CONFIG_IDLE: Any sysfs attribute can be written freely + * @CXL_CONFIG_INTERLEAVE_ACTIVE: region size has been set, no more + * changes to interleave_ways or interleave_granularity * @CXL_CONFIG_ACTIVE: All targets have been added the region is now * active */ enum cxl_config_state { CXL_CONFIG_IDLE, + CXL_CONFIG_INTERLEAVE_ACTIVE, CXL_CONFIG_ACTIVE, }; @@ -310,12 +339,16 @@ enum cxl_config_state { * struct cxl_region_params - region settings * @state: allow the driver to lockdown further parameter changes * @uuid: unique id for persistent regions + * @interleave_ways: number of endpoints in the region + * @interleave_granularity: capacity each endpoint contributes to a stripe * * State transitions are protected by the cxl_region_rwsem */ struct cxl_region_params { enum cxl_config_state state; uuid_t uuid; + int interleave_ways; + int interleave_granularity; }; /**
