| Message ID | 20220128002707.391076-2-ben.widawsky@intel.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | CXL Region driver | expand |
On Thu, Jan 27, 2022 at 4:27 PM Ben Widawsky <ben.widawsky@intel.com> wrote: > > Regions are created as a child of the decoder that encompasses an > address space with constraints. Regions have a number of attributes that > must be configured before the region can be activated. > > The ABI is not meant to be secure, but is meant to avoid accidental > races. As a result, a buggy process may create a region by name that was > allocated by a different process. However, multiple processes which are > trying not to race with each other shouldn't need special > synchronization to do so. > > // Allocate a new region name > region=$(cat /sys/bus/cxl/devices/decoder0.0/create_region) > > // Create a new region by name > echo $region > /sys/bus/cxl/devices/decoder0.0/create_region Were I someone coming in cold to this the immediate question about this example would be "what if userspace races to create the region?". How about showing the example that this interface requires looping until the kernel returns success in case userspace races itself to create the next region? I think this would work for that purpose. --- while region=$(cat /sys/bus/cxl/devices/decoder0.0/create_region) ! echo $region > /sys/bus/cxl/devices/decoder0.0/create_region do true; done --- > // Region now exists in sysfs > stat -t /sys/bus/cxl/devices/decoder0.0/$region > > // Delete the region, and name > echo $region > /sys/bus/cxl/devices/decoder0.0/delete_region > > Signed-off-by: Ben Widawsky <ben.widawsky@intel.com> > > --- > Changes since v2: > - Rename 'region' variables to 'cxlr' > - Update ABI docs for possible actual upstream version > --- > Documentation/ABI/testing/sysfs-bus-cxl | 24 ++ > .../driver-api/cxl/memory-devices.rst | 11 + > drivers/cxl/core/Makefile | 1 + > drivers/cxl/core/core.h | 3 + > drivers/cxl/core/port.c | 16 ++ > drivers/cxl/core/region.c | 208 ++++++++++++++++++ > drivers/cxl/cxl.h | 9 + > drivers/cxl/region.h | 38 ++++ > tools/testing/cxl/Kbuild | 1 + > 9 files changed, 311 insertions(+) > create mode 100644 drivers/cxl/core/region.c > create mode 100644 drivers/cxl/region.h > > diff --git a/Documentation/ABI/testing/sysfs-bus-cxl b/Documentation/ABI/testing/sysfs-bus-cxl > index 7c2b846521f3..dcc728458936 100644 > --- a/Documentation/ABI/testing/sysfs-bus-cxl > +++ b/Documentation/ABI/testing/sysfs-bus-cxl > @@ -163,3 +163,27 @@ Description: > memory (type-3). The 'target_type' attribute indicates the > current setting which may dynamically change based on what > memory regions are activated in this decode hierarchy. > + > +What: /sys/bus/cxl/devices/decoderX.Y/create_region > +Date: August, 2021 Maybe move this to January, 2022? > +KernelVersion: v5.18 > +Contact: linux-cxl@vger.kernel.org > +Description: > + Creates a new CXL region. Writing a value of the form > + "regionX.Y:Z" will create a new uninitialized region that will > + be mapped by the CXL decoderX.Y. "Write a value of the form 'regionX.Y:Z' to instantiate a new region within the decode range bounded by decoderX.Y." > + Reading from this node will > + return a newly allocated region name. In order to create a > + region (writing) you must use a value returned from reading the > + node. "The value written must match the current value returned from reading this attribute. This behavior lets the kernel arbitrate racing attempts to create a region. The thread that fails to write loops and tries the next value." > + subsequently configured and bound to a region driver before they > + can be used. > + > +What: /sys/bus/cxl/devices/decoderX.Y/delete_region > +Date: August, 2021 > +KernelVersion: v5.18 > +Contact: linux-cxl@vger.kernel.org > +Description: > + Deletes the named region. A region must be unbound from the > + region driver before being deleted. ....why does it need to be unbound first? device_unregister() triggers device_release_driver()? Side note: I am more and more thinking that even though the BIOS may try to lock some configurations down, if the system owner wants the region deleted the kernel should probably do everything in its power to oblige and override the BIOS including secondary bus resets to get the decoders unlocked. I.e. either the driver needs to hide the delete region attribute for locked regions, or it needs to give as much power to root as someone who has physical access and can rip out devices that are decoding locked ranges. Something we can discuss later, but every 'disable' and 'delete' interface requires answering the question "what about 'locked' configs and hot-remove?". > + region in the form "regionX.Y:Z". The region's name, allocated > + by reading create_region, will also be released. > diff --git a/Documentation/driver-api/cxl/memory-devices.rst b/Documentation/driver-api/cxl/memory-devices.rst > index db476bb170b6..66ddc58a21b1 100644 > --- a/Documentation/driver-api/cxl/memory-devices.rst > +++ b/Documentation/driver-api/cxl/memory-devices.rst > @@ -362,6 +362,17 @@ CXL Core > .. kernel-doc:: drivers/cxl/core/mbox.c > :doc: cxl mbox > > +CXL Regions > +----------- > +.. kernel-doc:: drivers/cxl/region.h > + :identifiers: > + > +.. kernel-doc:: drivers/cxl/core/region.c > + :doc: cxl core region > + > +.. kernel-doc:: drivers/cxl/core/region.c > + :identifiers: > + > External Interfaces > =================== > > diff --git a/drivers/cxl/core/Makefile b/drivers/cxl/core/Makefile > index 6d37cd78b151..39ce8f2f2373 100644 > --- a/drivers/cxl/core/Makefile > +++ b/drivers/cxl/core/Makefile > @@ -4,6 +4,7 @@ obj-$(CONFIG_CXL_BUS) += cxl_core.o > ccflags-y += -I$(srctree)/drivers/cxl > cxl_core-y := port.o > cxl_core-y += pmem.o > +cxl_core-y += region.o > cxl_core-y += regs.o > cxl_core-y += memdev.o > cxl_core-y += mbox.o > diff --git a/drivers/cxl/core/core.h b/drivers/cxl/core/core.h > index efbaa851929d..35fd08d560e2 100644 > --- a/drivers/cxl/core/core.h > +++ b/drivers/cxl/core/core.h > @@ -10,6 +10,9 @@ extern const struct device_type cxl_memdev_type; > > extern struct attribute_group cxl_base_attribute_group; > > +extern struct device_attribute dev_attr_create_region; > +extern struct device_attribute dev_attr_delete_region; > + > struct cxl_send_command; > struct cxl_mem_query_commands; > int cxl_query_cmd(struct cxl_memdev *cxlmd, > diff --git a/drivers/cxl/core/port.c b/drivers/cxl/core/port.c > index 631dec0fa79e..0826208b2bdf 100644 > --- a/drivers/cxl/core/port.c > +++ b/drivers/cxl/core/port.c > @@ -215,6 +215,8 @@ static struct attribute_group cxl_decoder_base_attribute_group = { > }; > > static struct attribute *cxl_decoder_root_attrs[] = { > + &dev_attr_create_region.attr, > + &dev_attr_delete_region.attr, > &dev_attr_cap_pmem.attr, > &dev_attr_cap_ram.attr, > &dev_attr_cap_type2.attr, > @@ -267,11 +269,23 @@ static const struct attribute_group *cxl_decoder_endpoint_attribute_groups[] = { > NULL, > }; > > +static int delete_region(struct device *dev, void *arg) > +{ > + struct cxl_decoder *cxld = to_cxl_decoder(dev->parent); > + > + return cxl_delete_region(cxld, dev_name(dev)); > +} > + > static void cxl_decoder_release(struct device *dev) > { > struct cxl_decoder *cxld = to_cxl_decoder(dev); > struct cxl_port *port = to_cxl_port(dev->parent); > > + device_for_each_child(&cxld->dev, cxld, delete_region); This is too late. Regions should be deleted before the decoder is unregistered, and I think it happens naturally due to the root port association with memdevs. I.e. a root decoder is unregistered by its parent port being unregistered which is triggered by cxl_acpi ->remove(). That ->remove() event triggers all memdevs to disconnect, albeit in a workqueue. So as long as cxl_acpi ->remove flushes that workqueue then it knows that all memdevs have triggered ->remove(). If the behavior of a region is that it gets deleted upon the last memdev being unmapped from it then there should not be any regions to clean up at decoder release time. > + > + dev_WARN_ONCE(dev, !ida_is_empty(&cxld->region_ida), > + "Lost track of a region"); > + > ida_free(&port->decoder_ida, cxld->id); > kfree(cxld); > } > @@ -1194,6 +1208,8 @@ static struct cxl_decoder *cxl_decoder_alloc(struct cxl_port *port, > cxld->target_type = CXL_DECODER_EXPANDER; > cxld->platform_res = (struct resource)DEFINE_RES_MEM(0, 0); > > + ida_init(&cxld->region_ida); > + > return cxld; > err: > kfree(cxld); > diff --git a/drivers/cxl/core/region.c b/drivers/cxl/core/region.c > new file mode 100644 > index 000000000000..1a448543db0d > --- /dev/null > +++ b/drivers/cxl/core/region.c > @@ -0,0 +1,208 @@ > +// SPDX-License-Identifier: GPL-2.0-only > +/* Copyright(c) 2021 Intel Corporation. All rights reserved. */ Happy New Year! Let's go to 2022 here. > +#include <linux/io-64-nonatomic-lo-hi.h> > +#include <linux/device.h> > +#include <linux/module.h> > +#include <linux/slab.h> > +#include <linux/idr.h> > +#include <region.h> > +#include <cxl.h> > +#include "core.h" > + > +/** > + * DOC: cxl core region > + * > + * Regions are managed through the Linux device model. Each region instance is a > + * unique struct device. CXL core provides functionality to create, destroy, and > + * configure regions. This is all implemented here. Binding a region > + * (programming the hardware) is handled by a separate region driver. > + */ Somewhat information lite, how about: "CXL Regions represent mapped memory capacity in system physical address space. Whereas the CXL Root Decoders identify the bounds of potential CXL Memory ranges, Regions represent the active mapped capacity by the HDM Decoder Capability structures throughout the Host Bridges, Switches, and Endpoints in the topology." > + > +static void cxl_region_release(struct device *dev); > + > +static const struct device_type cxl_region_type = { > + .name = "cxl_region", > + .release = cxl_region_release, > +}; > + > +static ssize_t create_region_show(struct device *dev, > + struct device_attribute *attr, char *buf) > +{ > + struct cxl_port *port = to_cxl_port(dev->parent); > + struct cxl_decoder *cxld = to_cxl_decoder(dev); > + int rc; > + > + if (dev_WARN_ONCE(dev, !is_root_decoder(dev), > + "Invalid decoder selected for region.")) { > + return -ENODEV; > + } This can go, it's already the case that this attribute is only listed in 'cxl_decoder_root_attrs' > + rc = ida_alloc(&cxld->region_ida, GFP_KERNEL); This looks broken. What if userspace does: region=$(cat /sys/bus/cxl/devices/decoder0.0/create_region) region=$(cat /sys/bus/cxl/devices/decoder0.0/create_region) echo $region > /sys/bus/cxl/devices/decoder0.0/create_region ...i.e. it should only advance to create a new name after the previous one was instantiated / confirmed via a write. Also, sysfs values are world readable by default, so non-root can burn up region_ida. > + if (rc < 0) { > + dev_err(&cxld->dev, "Couldn't get a new id\n"); > + return rc; > + } > + > + return sysfs_emit(buf, "region%d.%d:%d\n", port->id, cxld->id, rc); > +} > + > +static ssize_t create_region_store(struct device *dev, > + struct device_attribute *attr, > + const char *buf, size_t len) > +{ > + struct cxl_port *port = to_cxl_port(dev->parent); > + struct cxl_decoder *cxld = to_cxl_decoder(dev); > + int decoder_id, port_id, region_id; > + struct cxl_region *cxlr; > + ssize_t rc; > + > + if (sscanf(buf, "region%d.%d:%d", &port_id, &decoder_id, ®ion_id) != 3) > + return -EINVAL; With the proposed change above to cache the current 'next' region name this can just be something like: sysfs_streq(buf, cxld->next); > + > + if (decoder_id != cxld->id) > + return -EINVAL; > + > + if (port_id != port->id) > + return -EINVAL; > + > + cxlr = cxl_alloc_region(cxld, region_id); > + if (IS_ERR(cxlr)) > + return PTR_ERR(cxlr); > + > + rc = cxl_add_region(cxld, cxlr); > + if (rc) { > + kfree(cxlr); ...'add' failures usually require a put_device(), are you sure kfree() is correct here. > + return rc; > + } > + > + return len; > +} > +DEVICE_ATTR_RW(create_region); > + > +static ssize_t delete_region_store(struct device *dev, > + struct device_attribute *attr, > + const char *buf, size_t len) > +{ > + struct cxl_decoder *cxld = to_cxl_decoder(dev); > + int rc; > + > + rc = cxl_delete_region(cxld, buf); I would have expected symmetry with cxl_add_region() i.e. convert @buf to @cxlr and keep the function signatures between add and delete aligned. > + if (rc) > + return rc; > + > + return len; > +} > +DEVICE_ATTR_WO(delete_region); > + > +struct cxl_region *to_cxl_region(struct device *dev) > +{ > + if (dev_WARN_ONCE(dev, dev->type != &cxl_region_type, > + "not a cxl_region device\n")) > + return NULL; > + > + return container_of(dev, struct cxl_region, dev); > +} > +EXPORT_SYMBOL_GPL(to_cxl_region); > + > +static void cxl_region_release(struct device *dev) > +{ > + struct cxl_decoder *cxld = to_cxl_decoder(dev->parent); > + struct cxl_region *cxlr = to_cxl_region(dev); > + > + ida_free(&cxld->region_ida, cxlr->id); > + kfree(cxlr); > +} > + > +struct cxl_region *cxl_alloc_region(struct cxl_decoder *cxld, int id) > +{ > + struct cxl_region *cxlr; > + > + cxlr = kzalloc(sizeof(*cxlr), GFP_KERNEL); > + if (!cxlr) > + return ERR_PTR(-ENOMEM); To keep symmetry with other device object allocations in the cxl/core I would expect to see the device_initialize() dev->type and dev->bus setup occur here as well. > + > + cxlr->id = id; > + > + return cxlr; > +} > + > +/** > + * cxl_add_region - Adds a region to a decoder > + * @cxld: Parent decoder. > + * @cxlr: Region to be added to the decoder. > + * > + * This is the second step of region initialization. Regions exist within an > + * address space which is mapped by a @cxld. That @cxld must be a root decoder, > + * and it enforces constraints upon the region as it is configured. > + * > + * Return: 0 if the region was added to the @cxld, else returns negative error > + * code. The region will be named "regionX.Y.Z" where X is the port, Y is the > + * decoder id, and Z is the region number. > + */ > +int cxl_add_region(struct cxl_decoder *cxld, struct cxl_region *cxlr) > +{ > + struct cxl_port *port = to_cxl_port(cxld->dev.parent); > + struct device *dev = &cxlr->dev; > + int rc; > + > + device_initialize(dev); > + dev->parent = &cxld->dev; > + device_set_pm_not_required(dev); > + dev->bus = &cxl_bus_type; > + dev->type = &cxl_region_type; > + rc = dev_set_name(dev, "region%d.%d:%d", port->id, cxld->id, cxlr->id); > + if (rc) > + goto err; > + > + rc = device_add(dev); > + if (rc) > + goto err; > + > + dev_dbg(dev, "Added to %s\n", dev_name(&cxld->dev)); > + > + return 0; > + > +err: > + put_device(dev); Here is that put_device() I was expecting, that kfree() earlier was a double-free it seems. Also, I would have expected a devm action to remove this. Something like: struct cxl_port *port = to_cxl_port(cxld->dev.parent); cxl_device_lock(&port->dev); if (port->dev.driver) devm_cxl_add_region(port->uport, cxld, id); else rc = -ENXIO; cxl_device_unlock(&port->dev); ...then no matter what you know the region will be unregistered when the root port goes away. > + return rc; > +} > + > +static struct cxl_region *cxl_find_region_by_name(struct cxl_decoder *cxld, > + const char *name) > +{ > + struct device *region_dev; > + > + region_dev = device_find_child_by_name(&cxld->dev, name); > + if (!region_dev) > + return ERR_PTR(-ENOENT); > + > + return to_cxl_region(region_dev); > +} > + > +/** > + * cxl_delete_region - Deletes a region > + * @cxld: Parent decoder > + * @region_name: Named region, ie. regionX.Y:Z > + */ > +int cxl_delete_region(struct cxl_decoder *cxld, const char *region_name) > +{ > + struct cxl_region *cxlr; > + > + device_lock(&cxld->dev); cxl_device_lock() ...if the lock is needed, but I don't see why the lock is needed? > + > + cxlr = cxl_find_region_by_name(cxld, region_name); > + if (IS_ERR(cxlr)) { > + device_unlock(&cxld->dev); > + return PTR_ERR(cxlr); > + } > + > + dev_dbg(&cxld->dev, "Requested removal of %s from %s\n", > + dev_name(&cxlr->dev), dev_name(&cxld->dev)); > + > + device_unregister(&cxlr->dev); > + device_unlock(&cxld->dev); This would need to change to devm_release_action() of course if the add side changes to devm_cxl_add_region(). > + > + put_device(&cxlr->dev); > + > + return 0; > +} > diff --git a/drivers/cxl/cxl.h b/drivers/cxl/cxl.h > index 13fb06849199..b9f0099c1f39 100644 > --- a/drivers/cxl/cxl.h > +++ b/drivers/cxl/cxl.h > @@ -221,6 +221,7 @@ enum cxl_decoder_type { > * @target_type: accelerator vs expander (type2 vs type3) selector > * @flags: memory type capabilities and locking > * @target_lock: coordinate coherent reads of the target list > + * @region_ida: allocator for region ids. > * @nr_targets: number of elements in @target > * @target: active ordered target list in current decoder configuration > */ > @@ -236,6 +237,7 @@ struct cxl_decoder { > enum cxl_decoder_type target_type; > unsigned long flags; > seqlock_t target_lock; > + struct ida region_ida; > int nr_targets; > struct cxl_dport *target[]; > }; > @@ -323,6 +325,13 @@ struct cxl_ep { > struct list_head list; > }; > > +bool is_cxl_region(struct device *dev); > +struct cxl_region *to_cxl_region(struct device *dev); > +struct cxl_region *cxl_alloc_region(struct cxl_decoder *cxld, > + int interleave_ways); > +int cxl_add_region(struct cxl_decoder *cxld, struct cxl_region *cxlr); > +int cxl_delete_region(struct cxl_decoder *cxld, const char *region); > + > static inline bool is_cxl_root(struct cxl_port *port) > { > return port->uport == port->dev.parent; > diff --git a/drivers/cxl/region.h b/drivers/cxl/region.h > new file mode 100644 > index 000000000000..eb1249e3c1d4 > --- /dev/null > +++ b/drivers/cxl/region.h > @@ -0,0 +1,38 @@ > +/* SPDX-License-Identifier: GPL-2.0-only */ > +/* Copyright(c) 2021 Intel Corporation. */ > +#ifndef __CXL_REGION_H__ > +#define __CXL_REGION_H__ > + > +#include <linux/uuid.h> > + > +#include "cxl.h" > + > +/** > + * struct cxl_region - CXL region > + * @dev: This region's device. > + * @id: This regions id. Id is globally unique across all regions. s/regions/region's/ > + * @list: Node in decoder's region list. > + * @res: Resource this region carves out of the platform decode range. > + * @config: HDM decoder program config > + * @config.size: Size of the region determined from LSA or userspace. > + * @config.uuid: The UUID for this region. > + * @config.interleave_ways: Number of interleave ways this region is configured for. > + * @config.interleave_granularity: Interleave granularity of region > + * @config.targets: The memory devices comprising the region. > + */ > +struct cxl_region { > + struct device dev; > + int id; > + struct list_head list; > + struct resource *res; > + > + struct { > + u64 size; > + uuid_t uuid; > + int interleave_ways; > + int interleave_granularity; > + struct cxl_memdev *targets[CXL_DECODER_MAX_INTERLEAVE]; > + } config; Why a sub-struct? > +}; > + > +#endif > diff --git a/tools/testing/cxl/Kbuild b/tools/testing/cxl/Kbuild > index 82e49ab0937d..3fe6d34e6d59 100644 > --- a/tools/testing/cxl/Kbuild > +++ b/tools/testing/cxl/Kbuild > @@ -46,6 +46,7 @@ cxl_core-y += $(CXL_CORE_SRC)/memdev.o > cxl_core-y += $(CXL_CORE_SRC)/mbox.o > cxl_core-y += $(CXL_CORE_SRC)/pci.o > cxl_core-y += $(CXL_CORE_SRC)/hdm.o > +cxl_core-y += $(CXL_CORE_SRC)/region.o > cxl_core-y += config_check.o > > obj-m += test/ > -- > 2.35.0 >
On Fri, Jan 28, 2022 at 10:14 AM Dan Williams <dan.j.williams@intel.com> wrote: [..] > Here is that put_device() I was expecting, that kfree() earlier was a > double-free it seems. > > Also, I would have expected a devm action to remove this. Something like: > > struct cxl_port *port = to_cxl_port(cxld->dev.parent); > > cxl_device_lock(&port->dev); > if (port->dev.driver) > devm_cxl_add_region(port->uport, cxld, id); > else > rc = -ENXIO; > cxl_device_unlock(&port->dev); > > ...then no matter what you know the region will be unregistered when > the root port goes away. ...actually, the lock and ->dev.driver check here are not needed because this attribute is only registered while the cxl_acpi driver is bound. So, it is safe to assume this is protected as decoder remove synchronizes against active sysfs users.
On Thu, 27 Jan 2022 16:26:54 -0800 Ben Widawsky <ben.widawsky@intel.com> wrote: > Regions are created as a child of the decoder that encompasses an > address space with constraints. Regions have a number of attributes that > must be configured before the region can be activated. > > The ABI is not meant to be secure, but is meant to avoid accidental > races. As a result, a buggy process may create a region by name that was > allocated by a different process. However, multiple processes which are > trying not to race with each other shouldn't need special > synchronization to do so. > > // Allocate a new region name > region=$(cat /sys/bus/cxl/devices/decoder0.0/create_region) > > // Create a new region by name > echo $region > /sys/bus/cxl/devices/decoder0.0/create_region > > // Region now exists in sysfs > stat -t /sys/bus/cxl/devices/decoder0.0/$region > > // Delete the region, and name > echo $region > /sys/bus/cxl/devices/decoder0.0/delete_region > > Signed-off-by: Ben Widawsky <ben.widawsky@intel.com> > One trivial comment below. > diff --git a/drivers/cxl/cxl.h b/drivers/cxl/cxl.h > index 13fb06849199..b9f0099c1f39 100644 > --- a/drivers/cxl/cxl.h > +++ b/drivers/cxl/cxl.h > @@ -221,6 +221,7 @@ enum cxl_decoder_type { > * @target_type: accelerator vs expander (type2 vs type3) selector > * @flags: memory type capabilities and locking > * @target_lock: coordinate coherent reads of the target list > + * @region_ida: allocator for region ids. > * @nr_targets: number of elements in @target > * @target: active ordered target list in current decoder configuration > */ > @@ -236,6 +237,7 @@ struct cxl_decoder { > enum cxl_decoder_type target_type; > unsigned long flags; > seqlock_t target_lock; > + struct ida region_ida; > int nr_targets; > struct cxl_dport *target[]; > }; > @@ -323,6 +325,13 @@ struct cxl_ep { > struct list_head list; > }; > > +bool is_cxl_region(struct device *dev); Not in this patch. Looks like it is in patch 4. > +struct cxl_region *to_cxl_region(struct device *dev); > +struct cxl_region *cxl_alloc_region(struct cxl_decoder *cxld, > + int interleave_ways); > +int cxl_add_region(struct cxl_decoder *cxld, struct cxl_region *cxlr); > +int cxl_delete_region(struct cxl_decoder *cxld, const char *region); > + > static inline bool is_cxl_root(struct cxl_port *port) > { > return port->uport == port->dev.parent;
On 22-01-28 10:14:09, Dan Williams wrote: > On Thu, Jan 27, 2022 at 4:27 PM Ben Widawsky <ben.widawsky@intel.com> wrote: > > > > Regions are created as a child of the decoder that encompasses an > > address space with constraints. Regions have a number of attributes that > > must be configured before the region can be activated. > > > > The ABI is not meant to be secure, but is meant to avoid accidental > > races. As a result, a buggy process may create a region by name that was > > allocated by a different process. However, multiple processes which are > > trying not to race with each other shouldn't need special > > synchronization to do so. > > > > // Allocate a new region name > > region=$(cat /sys/bus/cxl/devices/decoder0.0/create_region) > > > > // Create a new region by name > > echo $region > /sys/bus/cxl/devices/decoder0.0/create_region > > Were I someone coming in cold to this the immediate question about > this example would be "what if userspace races to create the region?". > How about showing the example that this interface requires looping > until the kernel returns success in case userspace races itself to > create the next region? I think this would work for that purpose. > > --- > > while > region=$(cat /sys/bus/cxl/devices/decoder0.0/create_region) > ! echo $region > /sys/bus/cxl/devices/decoder0.0/create_region > do true; done > > --- > See below... TL;DR the interface was designed to not work this way because I misunderstood you. > > // Region now exists in sysfs > > stat -t /sys/bus/cxl/devices/decoder0.0/$region > > > > // Delete the region, and name > > echo $region > /sys/bus/cxl/devices/decoder0.0/delete_region > > > > Signed-off-by: Ben Widawsky <ben.widawsky@intel.com> > > > > --- > > Changes since v2: > > - Rename 'region' variables to 'cxlr' > > - Update ABI docs for possible actual upstream version > > --- > > Documentation/ABI/testing/sysfs-bus-cxl | 24 ++ > > .../driver-api/cxl/memory-devices.rst | 11 + > > drivers/cxl/core/Makefile | 1 + > > drivers/cxl/core/core.h | 3 + > > drivers/cxl/core/port.c | 16 ++ > > drivers/cxl/core/region.c | 208 ++++++++++++++++++ > > drivers/cxl/cxl.h | 9 + > > drivers/cxl/region.h | 38 ++++ > > tools/testing/cxl/Kbuild | 1 + > > 9 files changed, 311 insertions(+) > > create mode 100644 drivers/cxl/core/region.c > > create mode 100644 drivers/cxl/region.h > > > > diff --git a/Documentation/ABI/testing/sysfs-bus-cxl b/Documentation/ABI/testing/sysfs-bus-cxl > > index 7c2b846521f3..dcc728458936 100644 > > --- a/Documentation/ABI/testing/sysfs-bus-cxl > > +++ b/Documentation/ABI/testing/sysfs-bus-cxl > > @@ -163,3 +163,27 @@ Description: > > memory (type-3). The 'target_type' attribute indicates the > > current setting which may dynamically change based on what > > memory regions are activated in this decode hierarchy. > > + > > +What: /sys/bus/cxl/devices/decoderX.Y/create_region > > +Date: August, 2021 > > Maybe move this to January, 2022? > Okay. > > +KernelVersion: v5.18 > > +Contact: linux-cxl@vger.kernel.org > > +Description: > > + Creates a new CXL region. Writing a value of the form > > + "regionX.Y:Z" will create a new uninitialized region that will > > + be mapped by the CXL decoderX.Y. > > "Write a value of the form 'regionX.Y:Z' to instantiate a new region > within the decode range bounded by decoderX.Y." > > > + Reading from this node will > > + return a newly allocated region name. In order to create a > > + region (writing) you must use a value returned from reading the > > + node. > > "The value written must match the current value returned from reading > this attribute. This behavior lets the kernel arbitrate racing > attempts to create a region. The thread that fails to write loops and > tries the next value." Okay. > > > + subsequently configured and bound to a region driver before they > > + can be used. > > + > > +What: /sys/bus/cxl/devices/decoderX.Y/delete_region > > +Date: August, 2021 > > +KernelVersion: v5.18 > > +Contact: linux-cxl@vger.kernel.org > > +Description: > > + Deletes the named region. A region must be unbound from the > > + region driver before being deleted. > > ....why does it need to be unbound first? device_unregister() triggers > device_release_driver()? It shouldn't. This must be old verbiage from when the operation was expected to be different. > > Side note: I am more and more thinking that even though the BIOS may > try to lock some configurations down, if the system owner wants the > region deleted the kernel should probably do everything in its power > to oblige and override the BIOS including secondary bus resets to get > the decoders unlocked. I.e. either the driver needs to hide the delete > region attribute for locked regions, or it needs to give as much power > to root as someone who has physical access and can rip out devices > that are decoding locked ranges. Something we can discuss later, but > every 'disable' and 'delete' interface requires answering the question > "what about 'locked' configs and hot-remove?". > When I originally started on these patches, I hadn't been planning to enumerate regions based on the current system programming. So the original answer would have been, the region is hidden. With that change of mind, I think it makes sense to do everything in the driver's power to obey, however, it starts to get really messy if/when switch ports are decoding to other devices and need a reset to unlock decoders. With that in mind, first attempt should be to disallow deleting locked regions. Perhaps later we can add an "unlock" interface which must be used before delete. > > + region in the form "regionX.Y:Z". The region's name, allocated > > + by reading create_region, will also be released. > > diff --git a/Documentation/driver-api/cxl/memory-devices.rst b/Documentation/driver-api/cxl/memory-devices.rst > > index db476bb170b6..66ddc58a21b1 100644 > > --- a/Documentation/driver-api/cxl/memory-devices.rst > > +++ b/Documentation/driver-api/cxl/memory-devices.rst > > @@ -362,6 +362,17 @@ CXL Core > > .. kernel-doc:: drivers/cxl/core/mbox.c > > :doc: cxl mbox > > > > +CXL Regions > > +----------- > > +.. kernel-doc:: drivers/cxl/region.h > > + :identifiers: > > + > > +.. kernel-doc:: drivers/cxl/core/region.c > > + :doc: cxl core region > > + > > +.. kernel-doc:: drivers/cxl/core/region.c > > + :identifiers: > > + > > External Interfaces > > =================== > > > > diff --git a/drivers/cxl/core/Makefile b/drivers/cxl/core/Makefile > > index 6d37cd78b151..39ce8f2f2373 100644 > > --- a/drivers/cxl/core/Makefile > > +++ b/drivers/cxl/core/Makefile > > @@ -4,6 +4,7 @@ obj-$(CONFIG_CXL_BUS) += cxl_core.o > > ccflags-y += -I$(srctree)/drivers/cxl > > cxl_core-y := port.o > > cxl_core-y += pmem.o > > +cxl_core-y += region.o > > cxl_core-y += regs.o > > cxl_core-y += memdev.o > > cxl_core-y += mbox.o > > diff --git a/drivers/cxl/core/core.h b/drivers/cxl/core/core.h > > index efbaa851929d..35fd08d560e2 100644 > > --- a/drivers/cxl/core/core.h > > +++ b/drivers/cxl/core/core.h > > @@ -10,6 +10,9 @@ extern const struct device_type cxl_memdev_type; > > > > extern struct attribute_group cxl_base_attribute_group; > > > > +extern struct device_attribute dev_attr_create_region; > > +extern struct device_attribute dev_attr_delete_region; > > + > > struct cxl_send_command; > > struct cxl_mem_query_commands; > > int cxl_query_cmd(struct cxl_memdev *cxlmd, > > diff --git a/drivers/cxl/core/port.c b/drivers/cxl/core/port.c > > index 631dec0fa79e..0826208b2bdf 100644 > > --- a/drivers/cxl/core/port.c > > +++ b/drivers/cxl/core/port.c > > @@ -215,6 +215,8 @@ static struct attribute_group cxl_decoder_base_attribute_group = { > > }; > > > > static struct attribute *cxl_decoder_root_attrs[] = { > > + &dev_attr_create_region.attr, > > + &dev_attr_delete_region.attr, > > &dev_attr_cap_pmem.attr, > > &dev_attr_cap_ram.attr, > > &dev_attr_cap_type2.attr, > > @@ -267,11 +269,23 @@ static const struct attribute_group *cxl_decoder_endpoint_attribute_groups[] = { > > NULL, > > }; > > > > +static int delete_region(struct device *dev, void *arg) > > +{ > > + struct cxl_decoder *cxld = to_cxl_decoder(dev->parent); > > + > > + return cxl_delete_region(cxld, dev_name(dev)); > > +} > > + > > static void cxl_decoder_release(struct device *dev) > > { > > struct cxl_decoder *cxld = to_cxl_decoder(dev); > > struct cxl_port *port = to_cxl_port(dev->parent); > > > > + device_for_each_child(&cxld->dev, cxld, delete_region); > > This is too late. Regions should be deleted before the decoder is > unregistered, and I think it happens naturally due to the root port > association with memdevs. I.e. a root decoder is unregistered by its > parent port being unregistered which is triggered by cxl_acpi > ->remove(). That ->remove() event triggers all memdevs to disconnect, > albeit in a workqueue. So as long as cxl_acpi ->remove flushes that > workqueue then it knows that all memdevs have triggered ->remove(). > Yes, I agree with this. I wasn't entirely certain of what I was doing when I originally wrote this. However, it should probably become a WARN of some sort that no regions are left. > If the behavior of a region is that it gets deleted upon the last > memdev being unmapped from it then there should not be any regions to > clean up at decoder release time. > This is the goal, but not implemented yet. > > + > > + dev_WARN_ONCE(dev, !ida_is_empty(&cxld->region_ida), > > + "Lost track of a region"); > > + > > ida_free(&port->decoder_ida, cxld->id); > > kfree(cxld); > > } > > @@ -1194,6 +1208,8 @@ static struct cxl_decoder *cxl_decoder_alloc(struct cxl_port *port, > > cxld->target_type = CXL_DECODER_EXPANDER; > > cxld->platform_res = (struct resource)DEFINE_RES_MEM(0, 0); > > > > + ida_init(&cxld->region_ida); > > + > > return cxld; > > err: > > kfree(cxld); > > diff --git a/drivers/cxl/core/region.c b/drivers/cxl/core/region.c > > new file mode 100644 > > index 000000000000..1a448543db0d > > --- /dev/null > > +++ b/drivers/cxl/core/region.c > > @@ -0,0 +1,208 @@ > > +// SPDX-License-Identifier: GPL-2.0-only > > +/* Copyright(c) 2021 Intel Corporation. All rights reserved. */ > > Happy New Year! Let's go to 2022 here. > Sure. I've always wondered if it's supposed to be when it was written, or when it was merged. > > +#include <linux/io-64-nonatomic-lo-hi.h> > > +#include <linux/device.h> > > +#include <linux/module.h> > > +#include <linux/slab.h> > > +#include <linux/idr.h> > > +#include <region.h> > > +#include <cxl.h> > > +#include "core.h" > > + > > +/** > > + * DOC: cxl core region > > + * > > + * Regions are managed through the Linux device model. Each region instance is a > > + * unique struct device. CXL core provides functionality to create, destroy, and > > + * configure regions. This is all implemented here. Binding a region > > + * (programming the hardware) is handled by a separate region driver. > > + */ > > Somewhat information lite, how about: > > "CXL Regions represent mapped memory capacity in system physical > address space. Whereas the CXL Root Decoders identify the bounds of > potential CXL Memory ranges, Regions represent the active mapped > capacity by the HDM Decoder Capability structures throughout the Host > Bridges, Switches, and Endpoints in the topology." > Okay. > > + > > +static void cxl_region_release(struct device *dev); > > + > > +static const struct device_type cxl_region_type = { > > + .name = "cxl_region", > > + .release = cxl_region_release, > > +}; > > + > > +static ssize_t create_region_show(struct device *dev, > > + struct device_attribute *attr, char *buf) > > +{ > > + struct cxl_port *port = to_cxl_port(dev->parent); > > + struct cxl_decoder *cxld = to_cxl_decoder(dev); > > + int rc; > > + > > + if (dev_WARN_ONCE(dev, !is_root_decoder(dev), > > + "Invalid decoder selected for region.")) { > > + return -ENODEV; > > + } > > This can go, it's already the case that this attribute is only listed > in 'cxl_decoder_root_attrs' > > > + rc = ida_alloc(&cxld->region_ida, GFP_KERNEL); > > This looks broken. What if userspace does: > > region=$(cat /sys/bus/cxl/devices/decoder0.0/create_region) > region=$(cat /sys/bus/cxl/devices/decoder0.0/create_region) > echo $region > /sys/bus/cxl/devices/decoder0.0/create_region > > ...i.e. it should only advance to create a new name after the previous > one was instantiated / confirmed via a write. > > Also, sysfs values are world readable by default, so non-root can burn > up region_ida. > I misunderstood your original request for this interface. How it's working is by design. I'll change it to work the way you describe. > > + if (rc < 0) { > > + dev_err(&cxld->dev, "Couldn't get a new id\n"); > > + return rc; > > + } > > + > > + return sysfs_emit(buf, "region%d.%d:%d\n", port->id, cxld->id, rc); > > +} > > + > > +static ssize_t create_region_store(struct device *dev, > > + struct device_attribute *attr, > > + const char *buf, size_t len) > > +{ > > + struct cxl_port *port = to_cxl_port(dev->parent); > > + struct cxl_decoder *cxld = to_cxl_decoder(dev); > > + int decoder_id, port_id, region_id; > > + struct cxl_region *cxlr; > > + ssize_t rc; > > + > > + if (sscanf(buf, "region%d.%d:%d", &port_id, &decoder_id, ®ion_id) != 3) > > + return -EINVAL; > > With the proposed change above to cache the current 'next' region name > this can just be something like: > > sysfs_streq(buf, cxld->next); > Sounds good. > > + > > + if (decoder_id != cxld->id) > > + return -EINVAL; > > + > > + if (port_id != port->id) > > + return -EINVAL; > > + > > + cxlr = cxl_alloc_region(cxld, region_id); > > + if (IS_ERR(cxlr)) > > + return PTR_ERR(cxlr); > > + > > + rc = cxl_add_region(cxld, cxlr); > > + if (rc) { > > + kfree(cxlr); > > ...'add' failures usually require a put_device(), are you sure kfree() > is correct here. > You had requested, and I can't recall why, that regions are not devm managed. It sounds like you're asking for it to be devm managed. I wish I took more notes of our conversations... > > + return rc; > > + } > > + > > + return len; > > +} > > +DEVICE_ATTR_RW(create_region); > > + > > +static ssize_t delete_region_store(struct device *dev, > > + struct device_attribute *attr, > > + const char *buf, size_t len) > > +{ > > + struct cxl_decoder *cxld = to_cxl_decoder(dev); > > + int rc; > > + > > + rc = cxl_delete_region(cxld, buf); > > I would have expected symmetry with cxl_add_region() i.e. convert @buf > to @cxlr and keep the function signatures between add and delete > aligned. > > > + if (rc) > > + return rc; > > + > > + return len; > > +} > > +DEVICE_ATTR_WO(delete_region); > > + > > +struct cxl_region *to_cxl_region(struct device *dev) > > +{ > > + if (dev_WARN_ONCE(dev, dev->type != &cxl_region_type, > > + "not a cxl_region device\n")) > > + return NULL; > > + > > + return container_of(dev, struct cxl_region, dev); > > +} > > +EXPORT_SYMBOL_GPL(to_cxl_region); > > + > > +static void cxl_region_release(struct device *dev) > > +{ > > + struct cxl_decoder *cxld = to_cxl_decoder(dev->parent); > > + struct cxl_region *cxlr = to_cxl_region(dev); > > + > > + ida_free(&cxld->region_ida, cxlr->id); > > + kfree(cxlr); > > +} > > + > > +struct cxl_region *cxl_alloc_region(struct cxl_decoder *cxld, int id) > > +{ > > + struct cxl_region *cxlr; > > + > > + cxlr = kzalloc(sizeof(*cxlr), GFP_KERNEL); > > + if (!cxlr) > > + return ERR_PTR(-ENOMEM); > > To keep symmetry with other device object allocations in the cxl/core > I would expect to see the device_initialize() dev->type and dev->bus > setup occur here as well. > Okay. > > + > > + cxlr->id = id; > > + > > + return cxlr; > > +} > > + > > +/** > > + * cxl_add_region - Adds a region to a decoder > > + * @cxld: Parent decoder. > > + * @cxlr: Region to be added to the decoder. > > + * > > + * This is the second step of region initialization. Regions exist within an > > + * address space which is mapped by a @cxld. That @cxld must be a root decoder, > > + * and it enforces constraints upon the region as it is configured. > > + * > > + * Return: 0 if the region was added to the @cxld, else returns negative error > > + * code. The region will be named "regionX.Y.Z" where X is the port, Y is the > > + * decoder id, and Z is the region number. > > + */ > > +int cxl_add_region(struct cxl_decoder *cxld, struct cxl_region *cxlr) > > +{ > > + struct cxl_port *port = to_cxl_port(cxld->dev.parent); > > + struct device *dev = &cxlr->dev; > > + int rc; > > + > > + device_initialize(dev); > > + dev->parent = &cxld->dev; > > + device_set_pm_not_required(dev); > > + dev->bus = &cxl_bus_type; > > + dev->type = &cxl_region_type; > > + rc = dev_set_name(dev, "region%d.%d:%d", port->id, cxld->id, cxlr->id); > > + if (rc) > > + goto err; > > + > > + rc = device_add(dev); > > + if (rc) > > + goto err; > > + > > + dev_dbg(dev, "Added to %s\n", dev_name(&cxld->dev)); > > + > > + return 0; > > + > > +err: > > + put_device(dev); > > Here is that put_device() I was expecting, that kfree() earlier was a > double-free it seems. > > Also, I would have expected a devm action to remove this. Something like: > > struct cxl_port *port = to_cxl_port(cxld->dev.parent); > > cxl_device_lock(&port->dev); > if (port->dev.driver) > devm_cxl_add_region(port->uport, cxld, id); > else > rc = -ENXIO; > cxl_device_unlock(&port->dev); > > ...then no matter what you know the region will be unregistered when > the root port goes away. > Right. So as I said above, you had suggested devm wasn't the right interface. I can't recall why. I can rework it to use devm, and then it should work that way. > > + return rc; > > +} > > + > > +static struct cxl_region *cxl_find_region_by_name(struct cxl_decoder *cxld, > > + const char *name) > > +{ > > + struct device *region_dev; > > + > > + region_dev = device_find_child_by_name(&cxld->dev, name); > > + if (!region_dev) > > + return ERR_PTR(-ENOENT); > > + > > + return to_cxl_region(region_dev); > > +} > > + > > +/** > > + * cxl_delete_region - Deletes a region > > + * @cxld: Parent decoder > > + * @region_name: Named region, ie. regionX.Y:Z > > + */ > > +int cxl_delete_region(struct cxl_decoder *cxld, const char *region_name) > > +{ > > + struct cxl_region *cxlr; > > + > > + device_lock(&cxld->dev); > > cxl_device_lock() > > ...if the lock is needed, but I don't see why the lock is needed? > I don't see one either. I can't recall if I had one previously. > > + > > + cxlr = cxl_find_region_by_name(cxld, region_name); > > + if (IS_ERR(cxlr)) { > > + device_unlock(&cxld->dev); > > + return PTR_ERR(cxlr); > > + } > > + > > + dev_dbg(&cxld->dev, "Requested removal of %s from %s\n", > > + dev_name(&cxlr->dev), dev_name(&cxld->dev)); > > + > > + device_unregister(&cxlr->dev); > > + device_unlock(&cxld->dev); > > This would need to change to devm_release_action() of course if the > add side changes to devm_cxl_add_region(). > Yes. > > + > > + put_device(&cxlr->dev); > > + > > + return 0; > > +} > > diff --git a/drivers/cxl/cxl.h b/drivers/cxl/cxl.h > > index 13fb06849199..b9f0099c1f39 100644 > > --- a/drivers/cxl/cxl.h > > +++ b/drivers/cxl/cxl.h > > @@ -221,6 +221,7 @@ enum cxl_decoder_type { > > * @target_type: accelerator vs expander (type2 vs type3) selector > > * @flags: memory type capabilities and locking > > * @target_lock: coordinate coherent reads of the target list > > + * @region_ida: allocator for region ids. > > * @nr_targets: number of elements in @target > > * @target: active ordered target list in current decoder configuration > > */ > > @@ -236,6 +237,7 @@ struct cxl_decoder { > > enum cxl_decoder_type target_type; > > unsigned long flags; > > seqlock_t target_lock; > > + struct ida region_ida; > > int nr_targets; > > struct cxl_dport *target[]; > > }; > > @@ -323,6 +325,13 @@ struct cxl_ep { > > struct list_head list; > > }; > > > > +bool is_cxl_region(struct device *dev); > > +struct cxl_region *to_cxl_region(struct device *dev); > > +struct cxl_region *cxl_alloc_region(struct cxl_decoder *cxld, > > + int interleave_ways); > > +int cxl_add_region(struct cxl_decoder *cxld, struct cxl_region *cxlr); > > +int cxl_delete_region(struct cxl_decoder *cxld, const char *region); > > + > > static inline bool is_cxl_root(struct cxl_port *port) > > { > > return port->uport == port->dev.parent; > > diff --git a/drivers/cxl/region.h b/drivers/cxl/region.h > > new file mode 100644 > > index 000000000000..eb1249e3c1d4 > > --- /dev/null > > +++ b/drivers/cxl/region.h > > @@ -0,0 +1,38 @@ > > +/* SPDX-License-Identifier: GPL-2.0-only */ > > +/* Copyright(c) 2021 Intel Corporation. */ > > +#ifndef __CXL_REGION_H__ > > +#define __CXL_REGION_H__ > > + > > +#include <linux/uuid.h> > > + > > +#include "cxl.h" > > + > > +/** > > + * struct cxl_region - CXL region > > + * @dev: This region's device. > > + * @id: This regions id. Id is globally unique across all regions. > > s/regions/region's/ > > > + * @list: Node in decoder's region list. > > + * @res: Resource this region carves out of the platform decode range. > > + * @config: HDM decoder program config > > + * @config.size: Size of the region determined from LSA or userspace. > > + * @config.uuid: The UUID for this region. > > + * @config.interleave_ways: Number of interleave ways this region is configured for. > > + * @config.interleave_granularity: Interleave granularity of region > > + * @config.targets: The memory devices comprising the region. > > + */ > > +struct cxl_region { > > + struct device dev; > > + int id; > > + struct list_head list; > > + struct resource *res; > > + > > + struct { > > + u64 size; > > + uuid_t uuid; > > + int interleave_ways; > > + int interleave_granularity; > > + struct cxl_memdev *targets[CXL_DECODER_MAX_INTERLEAVE]; > > + } config; > > Why a sub-struct? > Just stylistic. I originally did have this as a named struct and used it as such. I will change it. > > +}; > > + > > +#endif > > diff --git a/tools/testing/cxl/Kbuild b/tools/testing/cxl/Kbuild > > index 82e49ab0937d..3fe6d34e6d59 100644 > > --- a/tools/testing/cxl/Kbuild > > +++ b/tools/testing/cxl/Kbuild > > @@ -46,6 +46,7 @@ cxl_core-y += $(CXL_CORE_SRC)/memdev.o > > cxl_core-y += $(CXL_CORE_SRC)/mbox.o > > cxl_core-y += $(CXL_CORE_SRC)/pci.o > > cxl_core-y += $(CXL_CORE_SRC)/hdm.o > > +cxl_core-y += $(CXL_CORE_SRC)/region.o > > cxl_core-y += config_check.o > > > > obj-m += test/ > > -- > > 2.35.0 > >
On 22-01-28 10:59:26, Dan Williams wrote: > On Fri, Jan 28, 2022 at 10:14 AM Dan Williams <dan.j.williams@intel.com> wrote: > [..] > > Here is that put_device() I was expecting, that kfree() earlier was a > > double-free it seems. > > > > Also, I would have expected a devm action to remove this. Something like: > > > > struct cxl_port *port = to_cxl_port(cxld->dev.parent); > > > > cxl_device_lock(&port->dev); > > if (port->dev.driver) > > devm_cxl_add_region(port->uport, cxld, id); I assume you mean devm_cxl_delete_region(), yes? > > else > > rc = -ENXIO; > > cxl_device_unlock(&port->dev); > > > > ...then no matter what you know the region will be unregistered when > > the root port goes away. > > ...actually, the lock and ->dev.driver check here are not needed > because this attribute is only registered while the cxl_acpi driver is > bound. So, it is safe to assume this is protected as decoder remove > synchronizes against active sysfs users. I'm somewhat confused when you say devm action to remove this. The current auto region deletion happens when the ->release() is called. Are you suggesting when the root decoder is removed I delete the regions at that point?
On 22-02-02 10:26:06, Ben Widawsky wrote: > On 22-01-28 10:59:26, Dan Williams wrote: > > On Fri, Jan 28, 2022 at 10:14 AM Dan Williams <dan.j.williams@intel.com> wrote: > > [..] > > > Here is that put_device() I was expecting, that kfree() earlier was a > > > double-free it seems. > > > > > > Also, I would have expected a devm action to remove this. Something like: > > > > > > struct cxl_port *port = to_cxl_port(cxld->dev.parent); > > > > > > cxl_device_lock(&port->dev); > > > if (port->dev.driver) > > > devm_cxl_add_region(port->uport, cxld, id); > > I assume you mean devm_cxl_delete_region(), yes? > > > > else > > > rc = -ENXIO; > > > cxl_device_unlock(&port->dev); > > > > > > ...then no matter what you know the region will be unregistered when > > > the root port goes away. > > > > ...actually, the lock and ->dev.driver check here are not needed > > because this attribute is only registered while the cxl_acpi driver is > > bound. So, it is safe to assume this is protected as decoder remove > > synchronizes against active sysfs users. > > I'm somewhat confused when you say devm action to remove this. The current auto > region deletion happens when the ->release() is called. Are you suggesting when > the root decoder is removed I delete the regions at that point? Hmm. I went back and looked and I had changed this functionality at some point... So forget I said that, it isn't how it's working currently. But the question remains, are you suggesting I delete in the root decoder unregistration?
On 22-02-02 10:28:11, Ben Widawsky wrote: > On 22-02-02 10:26:06, Ben Widawsky wrote: > > On 22-01-28 10:59:26, Dan Williams wrote: > > > On Fri, Jan 28, 2022 at 10:14 AM Dan Williams <dan.j.williams@intel.com> wrote: > > > [..] > > > > Here is that put_device() I was expecting, that kfree() earlier was a > > > > double-free it seems. > > > > > > > > Also, I would have expected a devm action to remove this. Something like: > > > > > > > > struct cxl_port *port = to_cxl_port(cxld->dev.parent); > > > > > > > > cxl_device_lock(&port->dev); > > > > if (port->dev.driver) > > > > devm_cxl_add_region(port->uport, cxld, id); > > > > I assume you mean devm_cxl_delete_region(), yes? > > > > > > else > > > > rc = -ENXIO; > > > > cxl_device_unlock(&port->dev); > > > > > > > > ...then no matter what you know the region will be unregistered when > > > > the root port goes away. > > > > > > ...actually, the lock and ->dev.driver check here are not needed > > > because this attribute is only registered while the cxl_acpi driver is > > > bound. So, it is safe to assume this is protected as decoder remove > > > synchronizes against active sysfs users. > > > > I'm somewhat confused when you say devm action to remove this. The current auto > > region deletion happens when the ->release() is called. Are you suggesting when > > the root decoder is removed I delete the regions at that point? > > Hmm. I went back and looked and I had changed this functionality at some > point... So forget I said that, it isn't how it's working currently. But the > question remains, are you suggesting I delete in the root decoder > unregistration? I think it's easier if I write what I think you mean.... Here are the relevant parts: devm_cxl_region_delete() is removed entirely. static void unregister_region(void *_cxlr) { struct cxl_region *cxlr = _cxlr; device_unregister(&cxlr->dev); } static int devm_cxl_region_add(struct cxl_decoder *cxld, struct cxl_region *cxlr) { struct cxl_port *port = to_cxl_port(cxld->dev.parent); struct device *dev = &cxlr->dev; int rc; rc = dev_set_name(dev, "region%d.%d:%d", port->id, cxld->id, cxlr->id); if (rc) return rc; rc = device_add(dev); if (rc) return rc; return devm_add_action_or_reset(&cxld->dev, unregister_region, cxlr); } static ssize_t delete_region_store(struct device *dev, struct device_attribute *attr, const char *buf, size_t len) { struct cxl_decoder *cxld = to_cxl_decoder(dev); struct cxl_region *cxlr; cxlr = cxl_find_region_by_name(cxld, buf); if (IS_ERR(cxlr)) return PTR_ERR(cxlr); devm_release_action(dev, unregister_region, cxlr); return len; } DEVICE_ATTR_WO(delete_region);
On Wed, Feb 2, 2022 at 10:48 AM Ben Widawsky <ben.widawsky@intel.com> wrote: > > On 22-02-02 10:28:11, Ben Widawsky wrote: > > On 22-02-02 10:26:06, Ben Widawsky wrote: > > > On 22-01-28 10:59:26, Dan Williams wrote: > > > > On Fri, Jan 28, 2022 at 10:14 AM Dan Williams <dan.j.williams@intel.com> wrote: > > > > [..] > > > > > Here is that put_device() I was expecting, that kfree() earlier was a > > > > > double-free it seems. > > > > > > > > > > Also, I would have expected a devm action to remove this. Something like: > > > > > > > > > > struct cxl_port *port = to_cxl_port(cxld->dev.parent); > > > > > > > > > > cxl_device_lock(&port->dev); > > > > > if (port->dev.driver) > > > > > devm_cxl_add_region(port->uport, cxld, id); > > > > > > I assume you mean devm_cxl_delete_region(), yes? > > > > > > > > else > > > > > rc = -ENXIO; > > > > > cxl_device_unlock(&port->dev); > > > > > > > > > > ...then no matter what you know the region will be unregistered when > > > > > the root port goes away. > > > > > > > > ...actually, the lock and ->dev.driver check here are not needed > > > > because this attribute is only registered while the cxl_acpi driver is > > > > bound. So, it is safe to assume this is protected as decoder remove > > > > synchronizes against active sysfs users. > > > > > > I'm somewhat confused when you say devm action to remove this. The current auto > > > region deletion happens when the ->release() is called. Are you suggesting when > > > the root decoder is removed I delete the regions at that point? > > > > Hmm. I went back and looked and I had changed this functionality at some > > point... So forget I said that, it isn't how it's working currently. But the > > question remains, are you suggesting I delete in the root decoder > > unregistration? > > I think it's easier if I write what I think you mean.... Here are the relevant > parts: > > devm_cxl_region_delete() is removed entirely. > > static void unregister_region(void *_cxlr) > { > struct cxl_region *cxlr = _cxlr; > > device_unregister(&cxlr->dev); > } > > > static int devm_cxl_region_add(struct cxl_decoder *cxld, struct cxl_region *cxlr) > { > struct cxl_port *port = to_cxl_port(cxld->dev.parent); > struct device *dev = &cxlr->dev; > int rc; > > rc = dev_set_name(dev, "region%d.%d:%d", port->id, cxld->id, cxlr->id); > if (rc) > return rc; > > rc = device_add(dev); > if (rc) > return rc; > > return devm_add_action_or_reset(&cxld->dev, unregister_region, cxlr); Decoders can't host devm actions. The host for this action would need to be the parent port. > } > > static ssize_t delete_region_store(struct device *dev, > struct device_attribute *attr, > const char *buf, size_t len) > { > struct cxl_decoder *cxld = to_cxl_decoder(dev); > struct cxl_region *cxlr; > > cxlr = cxl_find_region_by_name(cxld, buf); > if (IS_ERR(cxlr)) > return PTR_ERR(cxlr); > > devm_release_action(dev, unregister_region, cxlr); Yes, modulo the same comment as before that the decoder object is not a suitable devm host. This also needs a solution for the race between these 2 actions: echo "ACPI0017:00" > /sys/bus/platform/drivers/cxl_acpi/unbind echo $region > /sys/bus/cxl/devices/$decoder/delete_region
On 22-02-02 11:00:04, Dan Williams wrote: > On Wed, Feb 2, 2022 at 10:48 AM Ben Widawsky <ben.widawsky@intel.com> wrote: > > > > On 22-02-02 10:28:11, Ben Widawsky wrote: > > > On 22-02-02 10:26:06, Ben Widawsky wrote: > > > > On 22-01-28 10:59:26, Dan Williams wrote: > > > > > On Fri, Jan 28, 2022 at 10:14 AM Dan Williams <dan.j.williams@intel.com> wrote: > > > > > [..] > > > > > > Here is that put_device() I was expecting, that kfree() earlier was a > > > > > > double-free it seems. > > > > > > > > > > > > Also, I would have expected a devm action to remove this. Something like: > > > > > > > > > > > > struct cxl_port *port = to_cxl_port(cxld->dev.parent); > > > > > > > > > > > > cxl_device_lock(&port->dev); > > > > > > if (port->dev.driver) > > > > > > devm_cxl_add_region(port->uport, cxld, id); > > > > > > > > I assume you mean devm_cxl_delete_region(), yes? > > > > > > > > > > else > > > > > > rc = -ENXIO; > > > > > > cxl_device_unlock(&port->dev); > > > > > > > > > > > > ...then no matter what you know the region will be unregistered when > > > > > > the root port goes away. > > > > > > > > > > ...actually, the lock and ->dev.driver check here are not needed > > > > > because this attribute is only registered while the cxl_acpi driver is > > > > > bound. So, it is safe to assume this is protected as decoder remove > > > > > synchronizes against active sysfs users. > > > > > > > > I'm somewhat confused when you say devm action to remove this. The current auto > > > > region deletion happens when the ->release() is called. Are you suggesting when > > > > the root decoder is removed I delete the regions at that point? > > > > > > Hmm. I went back and looked and I had changed this functionality at some > > > point... So forget I said that, it isn't how it's working currently. But the > > > question remains, are you suggesting I delete in the root decoder > > > unregistration? > > > > I think it's easier if I write what I think you mean.... Here are the relevant > > parts: > > > > devm_cxl_region_delete() is removed entirely. > > > > static void unregister_region(void *_cxlr) > > { > > struct cxl_region *cxlr = _cxlr; > > > > device_unregister(&cxlr->dev); > > } > > > > > > static int devm_cxl_region_add(struct cxl_decoder *cxld, struct cxl_region *cxlr) > > { > > struct cxl_port *port = to_cxl_port(cxld->dev.parent); > > struct device *dev = &cxlr->dev; > > int rc; > > > > rc = dev_set_name(dev, "region%d.%d:%d", port->id, cxld->id, cxlr->id); > > if (rc) > > return rc; > > > > rc = device_add(dev); > > if (rc) > > return rc; > > > > return devm_add_action_or_reset(&cxld->dev, unregister_region, cxlr); > > Decoders can't host devm actions. The host for this action would need > to be the parent port. Happy to change it since I can't imagine a decoder would go down without the port also going down. Can you please explain why a decoder can't host a devm action though. I'd like to understand that better. > > > } > > > > static ssize_t delete_region_store(struct device *dev, > > struct device_attribute *attr, > > const char *buf, size_t len) > > { > > struct cxl_decoder *cxld = to_cxl_decoder(dev); > > struct cxl_region *cxlr; > > > > cxlr = cxl_find_region_by_name(cxld, buf); > > if (IS_ERR(cxlr)) > > return PTR_ERR(cxlr); > > > > devm_release_action(dev, unregister_region, cxlr); > > Yes, modulo the same comment as before that the decoder object is not > a suitable devm host. This also needs a solution for the race between > these 2 actions: > > echo "ACPI0017:00" > /sys/bus/platform/drivers/cxl_acpi/unbind > echo $region > /sys/bus/cxl/devices/$decoder/delete_region Is there a better solution than taking the root port lock?
On Wed, Feb 2, 2022 at 11:03 AM Ben Widawsky <ben.widawsky@intel.com> wrote: > > On 22-02-02 11:00:04, Dan Williams wrote: > > On Wed, Feb 2, 2022 at 10:48 AM Ben Widawsky <ben.widawsky@intel.com> wrote: > > > > > > On 22-02-02 10:28:11, Ben Widawsky wrote: > > > > On 22-02-02 10:26:06, Ben Widawsky wrote: > > > > > On 22-01-28 10:59:26, Dan Williams wrote: > > > > > > On Fri, Jan 28, 2022 at 10:14 AM Dan Williams <dan.j.williams@intel.com> wrote: > > > > > > [..] > > > > > > > Here is that put_device() I was expecting, that kfree() earlier was a > > > > > > > double-free it seems. > > > > > > > > > > > > > > Also, I would have expected a devm action to remove this. Something like: > > > > > > > > > > > > > > struct cxl_port *port = to_cxl_port(cxld->dev.parent); > > > > > > > > > > > > > > cxl_device_lock(&port->dev); > > > > > > > if (port->dev.driver) > > > > > > > devm_cxl_add_region(port->uport, cxld, id); > > > > > > > > > > I assume you mean devm_cxl_delete_region(), yes? > > > > > > > > > > > > else > > > > > > > rc = -ENXIO; > > > > > > > cxl_device_unlock(&port->dev); > > > > > > > > > > > > > > ...then no matter what you know the region will be unregistered when > > > > > > > the root port goes away. > > > > > > > > > > > > ...actually, the lock and ->dev.driver check here are not needed > > > > > > because this attribute is only registered while the cxl_acpi driver is > > > > > > bound. So, it is safe to assume this is protected as decoder remove > > > > > > synchronizes against active sysfs users. > > > > > > > > > > I'm somewhat confused when you say devm action to remove this. The current auto > > > > > region deletion happens when the ->release() is called. Are you suggesting when > > > > > the root decoder is removed I delete the regions at that point? > > > > > > > > Hmm. I went back and looked and I had changed this functionality at some > > > > point... So forget I said that, it isn't how it's working currently. But the > > > > question remains, are you suggesting I delete in the root decoder > > > > unregistration? > > > > > > I think it's easier if I write what I think you mean.... Here are the relevant > > > parts: > > > > > > devm_cxl_region_delete() is removed entirely. > > > > > > static void unregister_region(void *_cxlr) > > > { > > > struct cxl_region *cxlr = _cxlr; > > > > > > device_unregister(&cxlr->dev); > > > } > > > > > > > > > static int devm_cxl_region_add(struct cxl_decoder *cxld, struct cxl_region *cxlr) > > > { > > > struct cxl_port *port = to_cxl_port(cxld->dev.parent); > > > struct device *dev = &cxlr->dev; > > > int rc; > > > > > > rc = dev_set_name(dev, "region%d.%d:%d", port->id, cxld->id, cxlr->id); > > > if (rc) > > > return rc; > > > > > > rc = device_add(dev); > > > if (rc) > > > return rc; > > > > > > return devm_add_action_or_reset(&cxld->dev, unregister_region, cxlr); > > > > Decoders can't host devm actions. The host for this action would need > > to be the parent port. > > Happy to change it since I can't imagine a decoder would go down without the > port also going down. Can you please explain why a decoder can't host a devm > action though. I'd like to understand that better. So, devm releases resources at 2 times one of which is "too late". The natural / expected point at which they are released is by the driver core at $driver->remove($dev) time. There is also a backstop release point at $dev->${type,class,bus}->release() time. The latter one is "too late" because it effectively leave the device registered indefinitely which is broken because the parent sysfs directory hierarchy for that device will have already been removed, so the late release may crash depending on when the last put_device($dev) is performed. The decoder never experiences a ->remove() event, but it's parent port does (at least for non-root ports). For this case it will likely need to reach further up and use the same devm host as the decoder itself which is the ACPI0017 device. > > > > > > } > > > > > > static ssize_t delete_region_store(struct device *dev, > > > struct device_attribute *attr, > > > const char *buf, size_t len) > > > { > > > struct cxl_decoder *cxld = to_cxl_decoder(dev); > > > struct cxl_region *cxlr; > > > > > > cxlr = cxl_find_region_by_name(cxld, buf); > > > if (IS_ERR(cxlr)) > > > return PTR_ERR(cxlr); > > > > > > devm_release_action(dev, unregister_region, cxlr); > > > > Yes, modulo the same comment as before that the decoder object is not > > a suitable devm host. This also needs a solution for the race between > > these 2 actions: > > > > echo "ACPI0017:00" > /sys/bus/platform/drivers/cxl_acpi/unbind > > echo $region > /sys/bus/cxl/devices/$decoder/delete_region > > Is there a better solution than taking the root port lock? Depends what lockdep says. The first choice lock to synchronize those 2 actions would be the ACPI0017 device_lock, but lockdep might point out a problem with that vs sysfs teardown synchronization.
diff --git a/Documentation/ABI/testing/sysfs-bus-cxl b/Documentation/ABI/testing/sysfs-bus-cxl index 7c2b846521f3..dcc728458936 100644 --- a/Documentation/ABI/testing/sysfs-bus-cxl +++ b/Documentation/ABI/testing/sysfs-bus-cxl @@ -163,3 +163,27 @@ Description: memory (type-3). The 'target_type' attribute indicates the current setting which may dynamically change based on what memory regions are activated in this decode hierarchy. + +What: /sys/bus/cxl/devices/decoderX.Y/create_region +Date: August, 2021 +KernelVersion: v5.18 +Contact: linux-cxl@vger.kernel.org +Description: + Creates a new CXL region. Writing a value of the form + "regionX.Y:Z" will create a new uninitialized region that will + be mapped by the CXL decoderX.Y. Reading from this node will + return a newly allocated region name. In order to create a + region (writing) you must use a value returned from reading the + node. Regions must be created for root decoders, and must + subsequently configured and bound to a region driver before they + can be used. + +What: /sys/bus/cxl/devices/decoderX.Y/delete_region +Date: August, 2021 +KernelVersion: v5.18 +Contact: linux-cxl@vger.kernel.org +Description: + Deletes the named region. A region must be unbound from the + region driver before being deleted. The attributes expects a + region in the form "regionX.Y:Z". The region's name, allocated + by reading create_region, will also be released. diff --git a/Documentation/driver-api/cxl/memory-devices.rst b/Documentation/driver-api/cxl/memory-devices.rst index db476bb170b6..66ddc58a21b1 100644 --- a/Documentation/driver-api/cxl/memory-devices.rst +++ b/Documentation/driver-api/cxl/memory-devices.rst @@ -362,6 +362,17 @@ CXL Core .. kernel-doc:: drivers/cxl/core/mbox.c :doc: cxl mbox +CXL Regions +----------- +.. kernel-doc:: drivers/cxl/region.h + :identifiers: + +.. kernel-doc:: drivers/cxl/core/region.c + :doc: cxl core region + +.. kernel-doc:: drivers/cxl/core/region.c + :identifiers: + External Interfaces =================== diff --git a/drivers/cxl/core/Makefile b/drivers/cxl/core/Makefile index 6d37cd78b151..39ce8f2f2373 100644 --- a/drivers/cxl/core/Makefile +++ b/drivers/cxl/core/Makefile @@ -4,6 +4,7 @@ obj-$(CONFIG_CXL_BUS) += cxl_core.o ccflags-y += -I$(srctree)/drivers/cxl cxl_core-y := port.o cxl_core-y += pmem.o +cxl_core-y += region.o cxl_core-y += regs.o cxl_core-y += memdev.o cxl_core-y += mbox.o diff --git a/drivers/cxl/core/core.h b/drivers/cxl/core/core.h index efbaa851929d..35fd08d560e2 100644 --- a/drivers/cxl/core/core.h +++ b/drivers/cxl/core/core.h @@ -10,6 +10,9 @@ extern const struct device_type cxl_memdev_type; extern struct attribute_group cxl_base_attribute_group; +extern struct device_attribute dev_attr_create_region; +extern struct device_attribute dev_attr_delete_region; + struct cxl_send_command; struct cxl_mem_query_commands; int cxl_query_cmd(struct cxl_memdev *cxlmd, diff --git a/drivers/cxl/core/port.c b/drivers/cxl/core/port.c index 631dec0fa79e..0826208b2bdf 100644 --- a/drivers/cxl/core/port.c +++ b/drivers/cxl/core/port.c @@ -215,6 +215,8 @@ static struct attribute_group cxl_decoder_base_attribute_group = { }; static struct attribute *cxl_decoder_root_attrs[] = { + &dev_attr_create_region.attr, + &dev_attr_delete_region.attr, &dev_attr_cap_pmem.attr, &dev_attr_cap_ram.attr, &dev_attr_cap_type2.attr, @@ -267,11 +269,23 @@ static const struct attribute_group *cxl_decoder_endpoint_attribute_groups[] = { NULL, }; +static int delete_region(struct device *dev, void *arg) +{ + struct cxl_decoder *cxld = to_cxl_decoder(dev->parent); + + return cxl_delete_region(cxld, dev_name(dev)); +} + static void cxl_decoder_release(struct device *dev) { struct cxl_decoder *cxld = to_cxl_decoder(dev); struct cxl_port *port = to_cxl_port(dev->parent); + device_for_each_child(&cxld->dev, cxld, delete_region); + + dev_WARN_ONCE(dev, !ida_is_empty(&cxld->region_ida), + "Lost track of a region"); + ida_free(&port->decoder_ida, cxld->id); kfree(cxld); } @@ -1194,6 +1208,8 @@ static struct cxl_decoder *cxl_decoder_alloc(struct cxl_port *port, cxld->target_type = CXL_DECODER_EXPANDER; cxld->platform_res = (struct resource)DEFINE_RES_MEM(0, 0); + ida_init(&cxld->region_ida); + return cxld; err: kfree(cxld); diff --git a/drivers/cxl/core/region.c b/drivers/cxl/core/region.c new file mode 100644 index 000000000000..1a448543db0d --- /dev/null +++ b/drivers/cxl/core/region.c @@ -0,0 +1,208 @@ +// SPDX-License-Identifier: GPL-2.0-only +/* Copyright(c) 2021 Intel Corporation. All rights reserved. */ +#include <linux/io-64-nonatomic-lo-hi.h> +#include <linux/device.h> +#include <linux/module.h> +#include <linux/slab.h> +#include <linux/idr.h> +#include <region.h> +#include <cxl.h> +#include "core.h" + +/** + * DOC: cxl core region + * + * Regions are managed through the Linux device model. Each region instance is a + * unique struct device. CXL core provides functionality to create, destroy, and + * configure regions. This is all implemented here. Binding a region + * (programming the hardware) is handled by a separate region driver. + */ + +static void cxl_region_release(struct device *dev); + +static const struct device_type cxl_region_type = { + .name = "cxl_region", + .release = cxl_region_release, +}; + +static ssize_t create_region_show(struct device *dev, + struct device_attribute *attr, char *buf) +{ + struct cxl_port *port = to_cxl_port(dev->parent); + struct cxl_decoder *cxld = to_cxl_decoder(dev); + int rc; + + if (dev_WARN_ONCE(dev, !is_root_decoder(dev), + "Invalid decoder selected for region.")) { + return -ENODEV; + } + + rc = ida_alloc(&cxld->region_ida, GFP_KERNEL); + if (rc < 0) { + dev_err(&cxld->dev, "Couldn't get a new id\n"); + return rc; + } + + return sysfs_emit(buf, "region%d.%d:%d\n", port->id, cxld->id, rc); +} + +static ssize_t create_region_store(struct device *dev, + struct device_attribute *attr, + const char *buf, size_t len) +{ + struct cxl_port *port = to_cxl_port(dev->parent); + struct cxl_decoder *cxld = to_cxl_decoder(dev); + int decoder_id, port_id, region_id; + struct cxl_region *cxlr; + ssize_t rc; + + if (sscanf(buf, "region%d.%d:%d", &port_id, &decoder_id, ®ion_id) != 3) + return -EINVAL; + + if (decoder_id != cxld->id) + return -EINVAL; + + if (port_id != port->id) + return -EINVAL; + + cxlr = cxl_alloc_region(cxld, region_id); + if (IS_ERR(cxlr)) + return PTR_ERR(cxlr); + + rc = cxl_add_region(cxld, cxlr); + if (rc) { + kfree(cxlr); + return rc; + } + + return len; +} +DEVICE_ATTR_RW(create_region); + +static ssize_t delete_region_store(struct device *dev, + struct device_attribute *attr, + const char *buf, size_t len) +{ + struct cxl_decoder *cxld = to_cxl_decoder(dev); + int rc; + + rc = cxl_delete_region(cxld, buf); + if (rc) + return rc; + + return len; +} +DEVICE_ATTR_WO(delete_region); + +struct cxl_region *to_cxl_region(struct device *dev) +{ + if (dev_WARN_ONCE(dev, dev->type != &cxl_region_type, + "not a cxl_region device\n")) + return NULL; + + return container_of(dev, struct cxl_region, dev); +} +EXPORT_SYMBOL_GPL(to_cxl_region); + +static void cxl_region_release(struct device *dev) +{ + struct cxl_decoder *cxld = to_cxl_decoder(dev->parent); + struct cxl_region *cxlr = to_cxl_region(dev); + + ida_free(&cxld->region_ida, cxlr->id); + kfree(cxlr); +} + +struct cxl_region *cxl_alloc_region(struct cxl_decoder *cxld, int id) +{ + struct cxl_region *cxlr; + + cxlr = kzalloc(sizeof(*cxlr), GFP_KERNEL); + if (!cxlr) + return ERR_PTR(-ENOMEM); + + cxlr->id = id; + + return cxlr; +} + +/** + * cxl_add_region - Adds a region to a decoder + * @cxld: Parent decoder. + * @cxlr: Region to be added to the decoder. + * + * This is the second step of region initialization. Regions exist within an + * address space which is mapped by a @cxld. That @cxld must be a root decoder, + * and it enforces constraints upon the region as it is configured. + * + * Return: 0 if the region was added to the @cxld, else returns negative error + * code. The region will be named "regionX.Y.Z" where X is the port, Y is the + * decoder id, and Z is the region number. + */ +int cxl_add_region(struct cxl_decoder *cxld, struct cxl_region *cxlr) +{ + struct cxl_port *port = to_cxl_port(cxld->dev.parent); + struct device *dev = &cxlr->dev; + int rc; + + device_initialize(dev); + dev->parent = &cxld->dev; + device_set_pm_not_required(dev); + dev->bus = &cxl_bus_type; + dev->type = &cxl_region_type; + rc = dev_set_name(dev, "region%d.%d:%d", port->id, cxld->id, cxlr->id); + if (rc) + goto err; + + rc = device_add(dev); + if (rc) + goto err; + + dev_dbg(dev, "Added to %s\n", dev_name(&cxld->dev)); + + return 0; + +err: + put_device(dev); + return rc; +} + +static struct cxl_region *cxl_find_region_by_name(struct cxl_decoder *cxld, + const char *name) +{ + struct device *region_dev; + + region_dev = device_find_child_by_name(&cxld->dev, name); + if (!region_dev) + return ERR_PTR(-ENOENT); + + return to_cxl_region(region_dev); +} + +/** + * cxl_delete_region - Deletes a region + * @cxld: Parent decoder + * @region_name: Named region, ie. regionX.Y:Z + */ +int cxl_delete_region(struct cxl_decoder *cxld, const char *region_name) +{ + struct cxl_region *cxlr; + + device_lock(&cxld->dev); + + cxlr = cxl_find_region_by_name(cxld, region_name); + if (IS_ERR(cxlr)) { + device_unlock(&cxld->dev); + return PTR_ERR(cxlr); + } + + dev_dbg(&cxld->dev, "Requested removal of %s from %s\n", + dev_name(&cxlr->dev), dev_name(&cxld->dev)); + + device_unregister(&cxlr->dev); + device_unlock(&cxld->dev); + + put_device(&cxlr->dev); + + return 0; +} diff --git a/drivers/cxl/cxl.h b/drivers/cxl/cxl.h index 13fb06849199..b9f0099c1f39 100644 --- a/drivers/cxl/cxl.h +++ b/drivers/cxl/cxl.h @@ -221,6 +221,7 @@ enum cxl_decoder_type { * @target_type: accelerator vs expander (type2 vs type3) selector * @flags: memory type capabilities and locking * @target_lock: coordinate coherent reads of the target list + * @region_ida: allocator for region ids. * @nr_targets: number of elements in @target * @target: active ordered target list in current decoder configuration */ @@ -236,6 +237,7 @@ struct cxl_decoder { enum cxl_decoder_type target_type; unsigned long flags; seqlock_t target_lock; + struct ida region_ida; int nr_targets; struct cxl_dport *target[]; }; @@ -323,6 +325,13 @@ struct cxl_ep { struct list_head list; }; +bool is_cxl_region(struct device *dev); +struct cxl_region *to_cxl_region(struct device *dev); +struct cxl_region *cxl_alloc_region(struct cxl_decoder *cxld, + int interleave_ways); +int cxl_add_region(struct cxl_decoder *cxld, struct cxl_region *cxlr); +int cxl_delete_region(struct cxl_decoder *cxld, const char *region); + static inline bool is_cxl_root(struct cxl_port *port) { return port->uport == port->dev.parent; diff --git a/drivers/cxl/region.h b/drivers/cxl/region.h new file mode 100644 index 000000000000..eb1249e3c1d4 --- /dev/null +++ b/drivers/cxl/region.h @@ -0,0 +1,38 @@ +/* SPDX-License-Identifier: GPL-2.0-only */ +/* Copyright(c) 2021 Intel Corporation. */ +#ifndef __CXL_REGION_H__ +#define __CXL_REGION_H__ + +#include <linux/uuid.h> + +#include "cxl.h" + +/** + * struct cxl_region - CXL region + * @dev: This region's device. + * @id: This regions id. Id is globally unique across all regions. + * @list: Node in decoder's region list. + * @res: Resource this region carves out of the platform decode range. + * @config: HDM decoder program config + * @config.size: Size of the region determined from LSA or userspace. + * @config.uuid: The UUID for this region. + * @config.interleave_ways: Number of interleave ways this region is configured for. + * @config.interleave_granularity: Interleave granularity of region + * @config.targets: The memory devices comprising the region. + */ +struct cxl_region { + struct device dev; + int id; + struct list_head list; + struct resource *res; + + struct { + u64 size; + uuid_t uuid; + int interleave_ways; + int interleave_granularity; + struct cxl_memdev *targets[CXL_DECODER_MAX_INTERLEAVE]; + } config; +}; + +#endif diff --git a/tools/testing/cxl/Kbuild b/tools/testing/cxl/Kbuild index 82e49ab0937d..3fe6d34e6d59 100644 --- a/tools/testing/cxl/Kbuild +++ b/tools/testing/cxl/Kbuild @@ -46,6 +46,7 @@ cxl_core-y += $(CXL_CORE_SRC)/memdev.o cxl_core-y += $(CXL_CORE_SRC)/mbox.o cxl_core-y += $(CXL_CORE_SRC)/pci.o cxl_core-y += $(CXL_CORE_SRC)/hdm.o +cxl_core-y += $(CXL_CORE_SRC)/region.o cxl_core-y += config_check.o obj-m += test/
Regions are created as a child of the decoder that encompasses an address space with constraints. Regions have a number of attributes that must be configured before the region can be activated. The ABI is not meant to be secure, but is meant to avoid accidental races. As a result, a buggy process may create a region by name that was allocated by a different process. However, multiple processes which are trying not to race with each other shouldn't need special synchronization to do so. // Allocate a new region name region=$(cat /sys/bus/cxl/devices/decoder0.0/create_region) // Create a new region by name echo $region > /sys/bus/cxl/devices/decoder0.0/create_region // Region now exists in sysfs stat -t /sys/bus/cxl/devices/decoder0.0/$region // Delete the region, and name echo $region > /sys/bus/cxl/devices/decoder0.0/delete_region Signed-off-by: Ben Widawsky <ben.widawsky@intel.com> --- Changes since v2: - Rename 'region' variables to 'cxlr' - Update ABI docs for possible actual upstream version --- Documentation/ABI/testing/sysfs-bus-cxl | 24 ++ .../driver-api/cxl/memory-devices.rst | 11 + drivers/cxl/core/Makefile | 1 + drivers/cxl/core/core.h | 3 + drivers/cxl/core/port.c | 16 ++ drivers/cxl/core/region.c | 208 ++++++++++++++++++ drivers/cxl/cxl.h | 9 + drivers/cxl/region.h | 38 ++++ tools/testing/cxl/Kbuild | 1 + 9 files changed, 311 insertions(+) create mode 100644 drivers/cxl/core/region.c create mode 100644 drivers/cxl/region.h