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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>
71 lines
2.1 KiB
C
71 lines
2.1 KiB
C
// SPDX-License-Identifier: GPL-2.0
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/* Copyright(c) 2016 - 2018 Intel Corporation. All rights reserved. */
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#include <linux/memremap.h>
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#include <linux/module.h>
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#include <linux/pfn_t.h>
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#include "../../nvdimm/pfn.h"
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#include "../../nvdimm/nd.h"
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#include "../bus.h"
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struct dev_dax *__dax_pmem_probe(struct device *dev, enum dev_dax_subsys subsys)
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{
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struct resource res;
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int rc, id, region_id;
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resource_size_t offset;
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struct nd_pfn_sb *pfn_sb;
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struct dev_dax *dev_dax;
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struct nd_namespace_io *nsio;
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struct dax_region *dax_region;
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struct dev_pagemap pgmap = { 0 };
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struct nd_namespace_common *ndns;
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struct nd_dax *nd_dax = to_nd_dax(dev);
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struct nd_pfn *nd_pfn = &nd_dax->nd_pfn;
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struct nd_region *nd_region = to_nd_region(dev->parent);
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ndns = nvdimm_namespace_common_probe(dev);
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if (IS_ERR(ndns))
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return ERR_CAST(ndns);
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nsio = to_nd_namespace_io(&ndns->dev);
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/* parse the 'pfn' info block via ->rw_bytes */
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rc = devm_nsio_enable(dev, nsio);
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if (rc)
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return ERR_PTR(rc);
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rc = nvdimm_setup_pfn(nd_pfn, &pgmap);
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if (rc)
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return ERR_PTR(rc);
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devm_nsio_disable(dev, nsio);
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/* reserve the metadata area, device-dax will reserve the data */
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pfn_sb = nd_pfn->pfn_sb;
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offset = le64_to_cpu(pfn_sb->dataoff);
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if (!devm_request_mem_region(dev, nsio->res.start, offset,
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dev_name(&ndns->dev))) {
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dev_warn(dev, "could not reserve metadata\n");
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return ERR_PTR(-EBUSY);
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}
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rc = sscanf(dev_name(&ndns->dev), "namespace%d.%d", ®ion_id, &id);
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if (rc != 2)
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return ERR_PTR(-EINVAL);
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/* adjust the dax_region resource to the start of data */
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memcpy(&res, &pgmap.res, sizeof(res));
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res.start += offset;
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dax_region = alloc_dax_region(dev, region_id, &res,
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nd_region->target_node, le32_to_cpu(pfn_sb->align),
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PFN_DEV|PFN_MAP);
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if (!dax_region)
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return ERR_PTR(-ENOMEM);
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dev_dax = __devm_create_dev_dax(dax_region, id, &pgmap, subsys);
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/* child dev_dax instances now own the lifetime of the dax_region */
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dax_region_put(dax_region);
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return dev_dax;
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}
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EXPORT_SYMBOL_GPL(__dax_pmem_probe);
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MODULE_LICENSE("GPL v2");
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MODULE_AUTHOR("Intel Corporation");
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