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From:   Yang Shi <shy828301@gmail.com>
Date:   Mon, 12 Nov 2018 10:44:09 -0800
Message-ID: <CAHbLzkpXvvU=EDb+MCEgDcg=X25s1+mny+92QTTeMpUPX2K7Jw@mail.gmail.com>
Subject: Re: [PATCH] acpi/nfit, device-dax: Identify differentiated memory
 with a unique numa-node
To:     dan.j.williams@intel.com
Cc:     linux-nvdimm@lists.01.org, fan.du@intel.com, mpe@ellerman.id.au,
        oohall@gmail.com, dave.hansen@linux.intel.com, jglisse@redhat.com,
        linux-acpi@vger.kernel.org, Linux MM <linux-mm@kvack.org>,
        Linux Kernel Mailing List <linux-kernel@vger.kernel.org>
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On Fri, Nov 9, 2018 at 3:24 PM Dan Williams <dan.j.williams@intel.com> wrot=
e:
>
> 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://lkml.org/lkml/2018/10/23/9
>
> Reported-by: Fan Du <fan.du@intel.com>

Thanks for coming up with the patch quickly. We reported the problem
to Fan Du, and did a very similar, but preliminary,  in-house
implementation.

This implementation looks good to me. Reviewed-by: Yang Shi
<yang.shi@linux.alibaba.com>

> Cc: Michael Ellerman <mpe@ellerman.id.au>
> Cc: "Oliver O'Halloran" <oohall@gmail.com>
> Cc: Dave Hansen <dave.hansen@linux.intel.com>
> Cc: J=C3=A9r=C3=B4me Glisse <jglisse@redhat.com>
> Signed-off-by: Dan Williams <dan.j.williams@intel.com>
> ---
>  arch/powerpc/platforms/pseries/papr_scm.c |    1 +
>  drivers/acpi/nfit/core.c                  |    8 ++++++--
>  drivers/acpi/numa.c                       |    1 +
>  drivers/dax/bus.c                         |    4 +++-
>  drivers/dax/bus.h                         |    3 ++-
>  drivers/dax/dax-private.h                 |    4 ++++
>  drivers/dax/pmem/core.c                   |    4 +++-
>  drivers/nvdimm/e820.c                     |    1 +
>  drivers/nvdimm/nd.h                       |    2 +-
>  drivers/nvdimm/of_pmem.c                  |    1 +
>  drivers/nvdimm/region_devs.c              |    1 +
>  include/linux/libnvdimm.h                 |    1 +
>  12 files changed, 25 insertions(+), 6 deletions(-)
>
> diff --git a/arch/powerpc/platforms/pseries/papr_scm.c b/arch/powerpc/pla=
tforms/pseries/papr_scm.c
> index ee9372b65ca5..6a0a35b872d1 100644
> --- a/arch/powerpc/platforms/pseries/papr_scm.c
> +++ b/arch/powerpc/platforms/pseries/papr_scm.c
> @@ -233,6 +233,7 @@ static int papr_scm_nvdimm_init(struct papr_scm_priv =
*p)
>         memset(&ndr_desc, 0, sizeof(ndr_desc));
>         ndr_desc.attr_groups =3D region_attr_groups;
>         ndr_desc.numa_node =3D dev_to_node(&p->pdev->dev);
> +       ndr_desc.target_node =3D ndr_desc.numa_node;
>         ndr_desc.res =3D &p->res;
>         ndr_desc.of_node =3D p->dn;
>         ndr_desc.provider_data =3D p;
> diff --git a/drivers/acpi/nfit/core.c b/drivers/acpi/nfit/core.c
> index f8c638f3c946..2225e3de33ac 100644
> --- a/drivers/acpi/nfit/core.c
> +++ b/drivers/acpi/nfit/core.c
> @@ -2825,11 +2825,15 @@ static int acpi_nfit_register_region(struct acpi_=
nfit_desc *acpi_desc,
>         ndr_desc->res =3D &res;
>         ndr_desc->provider_data =3D nfit_spa;
>         ndr_desc->attr_groups =3D acpi_nfit_region_attribute_groups;
> -       if (spa->flags & ACPI_NFIT_PROXIMITY_VALID)
> +       if (spa->flags & ACPI_NFIT_PROXIMITY_VALID) {
>                 ndr_desc->numa_node =3D acpi_map_pxm_to_online_node(
>                                                 spa->proximity_domain);
> -       else
> +               ndr_desc->target_node =3D acpi_map_pxm_to_node(
> +                               spa->proximity_domain);
> +       } else {
>                 ndr_desc->numa_node =3D NUMA_NO_NODE;
> +               ndr_desc->target_node =3D NUMA_NO_NODE;
> +       }
>
>         /*
>          * Persistence domain bits are hierarchical, if
> diff --git a/drivers/acpi/numa.c b/drivers/acpi/numa.c
> index 274699463b4f..b9d86babb13a 100644
> --- a/drivers/acpi/numa.c
> +++ b/drivers/acpi/numa.c
> @@ -84,6 +84,7 @@ int acpi_map_pxm_to_node(int pxm)
>
>         return node;
>  }
> +EXPORT_SYMBOL(acpi_map_pxm_to_node);
>
>  /**
>   * acpi_map_pxm_to_online_node - Map proximity ID to online node
> diff --git a/drivers/dax/bus.c b/drivers/dax/bus.c
> index 568168500217..c620ad52d7e5 100644
> --- a/drivers/dax/bus.c
> +++ b/drivers/dax/bus.c
> @@ -214,7 +214,7 @@ static void dax_region_unregister(void *region)
>  }
>
>  struct dax_region *alloc_dax_region(struct device *parent, int region_id=
,
> -               struct resource *res, unsigned int align,
> +               struct resource *res, int target_node, unsigned int align=
,
>                 unsigned long pfn_flags)
>  {
>         struct dax_region *dax_region;
> @@ -244,6 +244,7 @@ struct dax_region *alloc_dax_region(struct device *pa=
rent, int region_id,
>         dax_region->id =3D region_id;
>         dax_region->align =3D align;
>         dax_region->dev =3D parent;
> +       dax_region->target_node =3D target_node;
>         if (sysfs_create_groups(&parent->kobj, dax_region_attribute_group=
s)) {
>                 kfree(dax_region);
>                 return NULL;
> @@ -348,6 +349,7 @@ struct dev_dax *__devm_create_dev_dax(struct dax_regi=
on *dax_region, int id,
>
>         dev_dax->dax_dev =3D dax_dev;
>         dev_dax->region =3D dax_region;
> +       dev_dax->target_node =3D dax_region->target_node;
>         kref_get(&dax_region->kref);
>
>         inode =3D dax_inode(dax_dev);
> diff --git a/drivers/dax/bus.h b/drivers/dax/bus.h
> index ce977552ffb5..8619e3299943 100644
> --- a/drivers/dax/bus.h
> +++ b/drivers/dax/bus.h
> @@ -10,7 +10,8 @@ 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, unsigned int align, unsigned long f=
lags);
> +               struct resource *res, int target_node, unsigned int align=
,
> +               unsigned long flags);
>
>  enum dev_dax_subsys {
>         DEV_DAX_BUS,
> diff --git a/drivers/dax/dax-private.h b/drivers/dax/dax-private.h
> index a82ce48f5884..a45612148ca0 100644
> --- a/drivers/dax/dax-private.h
> +++ b/drivers/dax/dax-private.h
> @@ -26,6 +26,7 @@ void dax_bus_exit(void);
>  /**
>   * struct dax_region - mapping infrastructure for dax devices
>   * @id: kernel-wide unique region for a memory range
> + * @target_node: effective numa node if this memory range is onlined
>   * @kref: to pin while other agents have a need to do lookups
>   * @dev: parent device backing this region
>   * @align: allocation and mapping alignment for child dax devices
> @@ -34,6 +35,7 @@ void dax_bus_exit(void);
>   */
>  struct dax_region {
>         int id;
> +       int target_node;
>         struct kref kref;
>         struct device *dev;
>         unsigned int align;
> @@ -46,6 +48,7 @@ struct dax_region {
>   * data while the device is activated in the driver.
>   * @region - parent region
>   * @dax_dev - core dax functionality
> + * @target_node: effective numa node if dev_dax memory range is onlined
>   * @dev - device core
>   * @pgmap - pgmap for memmap setup / lifetime (driver owned)
>   * @ref: pgmap reference count (driver owned)
> @@ -54,6 +57,7 @@ struct dax_region {
>  struct dev_dax {
>         struct dax_region *region;
>         struct dax_device *dax_dev;
> +       int target_node;
>         struct device dev;
>         struct dev_pagemap pgmap;
>         struct percpu_ref ref;
> diff --git a/drivers/dax/pmem/core.c b/drivers/dax/pmem/core.c
> index bdcff1b14e95..f71019ce0647 100644
> --- a/drivers/dax/pmem/core.c
> +++ b/drivers/dax/pmem/core.c
> @@ -20,6 +20,7 @@ struct dev_dax *__dax_pmem_probe(struct device *dev, en=
um dev_dax_subsys subsys)
>         struct nd_namespace_common *ndns;
>         struct nd_dax *nd_dax =3D to_nd_dax(dev);
>         struct nd_pfn *nd_pfn =3D &nd_dax->nd_pfn;
> +       struct nd_region *nd_region =3D to_nd_region(dev->parent);
>
>         ndns =3D nvdimm_namespace_common_probe(dev);
>         if (IS_ERR(ndns))
> @@ -52,7 +53,8 @@ struct dev_dax *__dax_pmem_probe(struct device *dev, en=
um dev_dax_subsys subsys)
>         memcpy(&res, &pgmap.res, sizeof(res));
>         res.start +=3D offset;
>         dax_region =3D alloc_dax_region(dev, region_id, &res,
> -                       le32_to_cpu(pfn_sb->align), PFN_DEV|PFN_MAP);
> +                       nd_region->target_node, le32_to_cpu(pfn_sb->align=
),
> +                       PFN_DEV|PFN_MAP);
>         if (!dax_region)
>                 return ERR_PTR(-ENOMEM);
>
> diff --git a/drivers/nvdimm/e820.c b/drivers/nvdimm/e820.c
> index 521eaf53a52a..36be9b619187 100644
> --- a/drivers/nvdimm/e820.c
> +++ b/drivers/nvdimm/e820.c
> @@ -47,6 +47,7 @@ static int e820_register_one(struct resource *res, void=
 *data)
>         ndr_desc.res =3D res;
>         ndr_desc.attr_groups =3D e820_pmem_region_attribute_groups;
>         ndr_desc.numa_node =3D e820_range_to_nid(res->start);
> +       ndr_desc.target_node =3D ndr_desc.numa_node;
>         set_bit(ND_REGION_PAGEMAP, &ndr_desc.flags);
>         if (!nvdimm_pmem_region_create(nvdimm_bus, &ndr_desc))
>                 return -ENXIO;
> diff --git a/drivers/nvdimm/nd.h b/drivers/nvdimm/nd.h
> index e79cc8e5c114..623216545cc8 100644
> --- a/drivers/nvdimm/nd.h
> +++ b/drivers/nvdimm/nd.h
> @@ -153,7 +153,7 @@ struct nd_region {
>         u16 ndr_mappings;
>         u64 ndr_size;
>         u64 ndr_start;
> -       int id, num_lanes, ro, numa_node;
> +       int id, num_lanes, ro, numa_node, target_node;
>         void *provider_data;
>         struct kernfs_node *bb_state;
>         struct badblocks bb;
> diff --git a/drivers/nvdimm/of_pmem.c b/drivers/nvdimm/of_pmem.c
> index 0a701837dfc0..ecaaa27438e2 100644
> --- a/drivers/nvdimm/of_pmem.c
> +++ b/drivers/nvdimm/of_pmem.c
> @@ -68,6 +68,7 @@ static int of_pmem_region_probe(struct platform_device =
*pdev)
>                 memset(&ndr_desc, 0, sizeof(ndr_desc));
>                 ndr_desc.attr_groups =3D region_attr_groups;
>                 ndr_desc.numa_node =3D dev_to_node(&pdev->dev);
> +               ndr_desc.target_node =3D ndr_desc.numa_node;
>                 ndr_desc.res =3D &pdev->resource[i];
>                 ndr_desc.of_node =3D np;
>                 set_bit(ND_REGION_PAGEMAP, &ndr_desc.flags);
> diff --git a/drivers/nvdimm/region_devs.c b/drivers/nvdimm/region_devs.c
> index 174a418cb171..86cd425b786d 100644
> --- a/drivers/nvdimm/region_devs.c
> +++ b/drivers/nvdimm/region_devs.c
> @@ -1060,6 +1060,7 @@ static struct nd_region *nd_region_create(struct nv=
dimm_bus *nvdimm_bus,
>         nd_region->flags =3D ndr_desc->flags;
>         nd_region->ro =3D ro;
>         nd_region->numa_node =3D ndr_desc->numa_node;
> +       nd_region->target_node =3D ndr_desc->target_node;
>         ida_init(&nd_region->ns_ida);
>         ida_init(&nd_region->btt_ida);
>         ida_init(&nd_region->pfn_ida);
> diff --git a/include/linux/libnvdimm.h b/include/linux/libnvdimm.h
> index 097072c5a852..941102c0c81f 100644
> --- a/include/linux/libnvdimm.h
> +++ b/include/linux/libnvdimm.h
> @@ -124,6 +124,7 @@ struct nd_region_desc {
>         void *provider_data;
>         int num_lanes;
>         int numa_node;
> +       int target_node;
>         unsigned long flags;
>         struct device_node *of_node;
>  };
>