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linux-next/drivers/dax/bus.h
Dan Williams 8fc5c73554 acpi/nfit, device-dax: Identify differentiated memory with a unique numa-node
Persistent memory, as described by the ACPI NFIT (NVDIMM Firmware
Interface Table), is the first known instance of a memory range
described by a unique "target" proximity domain. Where "initiator" and
"target" proximity domains is an approach that the ACPI HMAT
(Heterogeneous Memory Attributes Table) uses to described the unique
performance properties of a memory range relative to a given initiator
(e.g. CPU or DMA device).

Currently the numa-node for a /dev/pmemX block-device or /dev/daxX.Y
char-device follows the traditional notion of 'numa-node' where the
attribute conveys the closest online numa-node. That numa-node attribute
is useful for cpu-binding and memory-binding processes *near* the
device. However, when the memory range backing a 'pmem', or 'dax' device
is onlined (memory hot-add) the memory-only-numa-node representing that
address needs to be differentiated from the set of online nodes. In
other words, the numa-node association of the device depends on whether
you can bind processes *near* the cpu-numa-node in the offline
device-case, or bind process *on* the memory-range directly after the
backing address range is onlined.

Allow for the case that platform firmware describes persistent memory
with a unique proximity domain, i.e. when it is distinct from the
proximity of DRAM and CPUs that are on the same socket. Plumb the Linux
numa-node translation of that proximity through the libnvdimm region
device to namespaces that are in device-dax mode. With this in place the
proposed kmem driver [1] can optionally discover a unique numa-node
number for the address range as it transitions the memory from an
offline state managed by a device-driver to an online memory range
managed by the core-mm.

[1]: https://lore.kernel.org/lkml/20181022201317.8558C1D8@viggo.jf.intel.com

Reported-by: Fan Du <fan.du@intel.com>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: "Oliver O'Halloran" <oohall@gmail.com>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: Jérôme Glisse <jglisse@redhat.com>
Reviewed-by: Yang Shi <yang.shi@linux.alibaba.com>
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
2019-01-06 21:41:57 -08:00

62 lines
1.8 KiB
C

// SPDX-License-Identifier: GPL-2.0
/* Copyright(c) 2016 - 2018 Intel Corporation. All rights reserved. */
#ifndef __DAX_BUS_H__
#define __DAX_BUS_H__
#include <linux/device.h>
struct dev_dax;
struct resource;
struct dax_device;
struct dax_region;
void dax_region_put(struct dax_region *dax_region);
struct dax_region *alloc_dax_region(struct device *parent, int region_id,
struct resource *res, int target_node, unsigned int align,
unsigned long flags);
enum dev_dax_subsys {
DEV_DAX_BUS,
DEV_DAX_CLASS,
};
struct dev_dax *__devm_create_dev_dax(struct dax_region *dax_region, int id,
struct dev_pagemap *pgmap, enum dev_dax_subsys subsys);
static inline struct dev_dax *devm_create_dev_dax(struct dax_region *dax_region,
int id, struct dev_pagemap *pgmap)
{
return __devm_create_dev_dax(dax_region, id, pgmap, DEV_DAX_BUS);
}
/* to be deleted when DEV_DAX_CLASS is removed */
struct dev_dax *__dax_pmem_probe(struct device *dev, enum dev_dax_subsys subsys);
struct dax_device_driver {
struct device_driver drv;
struct list_head ids;
int match_always;
};
int __dax_driver_register(struct dax_device_driver *dax_drv,
struct module *module, const char *mod_name);
#define dax_driver_register(driver) \
__dax_driver_register(driver, THIS_MODULE, KBUILD_MODNAME)
void dax_driver_unregister(struct dax_device_driver *dax_drv);
void kill_dev_dax(struct dev_dax *dev_dax);
#if IS_ENABLED(CONFIG_DEV_DAX_PMEM_COMPAT)
int dev_dax_probe(struct device *dev);
#endif
/*
* While run_dax() is potentially a generic operation that could be
* defined in include/linux/dax.h we don't want to grow any users
* outside of drivers/dax/
*/
void run_dax(struct dax_device *dax_dev);
#define MODULE_ALIAS_DAX_DEVICE(type) \
MODULE_ALIAS("dax:t" __stringify(type) "*")
#define DAX_DEVICE_MODALIAS_FMT "dax:t%d"
#endif /* __DAX_BUS_H__ */