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    Subject[PATCH 4.14 62/67] libnvdimm, pfn: Pad pfn namespaces relative to other regions
    Date
    4.14-stable review patch.  If anyone has any objections, please let me know.

    ------------------

    From: Dan Williams <dan.j.williams@intel.com>

    commit ae86cbfef3818300f1972e52f67a93211acb0e24 upstream.

    Commit cfe30b872058 "libnvdimm, pmem: adjust for section collisions with
    'System RAM'" enabled Linux to workaround occasions where platform
    firmware arranges for "System RAM" and "Persistent Memory" to collide
    within a single section boundary. Unfortunately, as reported in this
    issue [1], platform firmware can inflict the same collision between
    persistent memory regions.

    The approach of interrogating iomem_resource does not work in this
    case because platform firmware may merge multiple regions into a single
    iomem_resource range. Instead provide a method to interrogate regions
    that share the same parent bus.

    This is a stop-gap until the core-MM can grow support for hotplug on
    sub-section boundaries.

    [1]: https://github.com/pmem/ndctl/issues/76

    Fixes: cfe30b872058 ("libnvdimm, pmem: adjust for section collisions with...")
    Cc: <stable@vger.kernel.org>
    Reported-by: Patrick Geary <patrickg@supermicro.com>
    Tested-by: Patrick Geary <patrickg@supermicro.com>
    Reviewed-by: Vishal Verma <vishal.l.verma@intel.com>
    Signed-off-by: Dan Williams <dan.j.williams@intel.com>
    Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

    ---
    drivers/nvdimm/nd-core.h | 2 +
    drivers/nvdimm/pfn_devs.c | 64 ++++++++++++++++++++++++-------------------
    drivers/nvdimm/region_devs.c | 41 +++++++++++++++++++++++++++
    3 files changed, 80 insertions(+), 27 deletions(-)

    --- a/drivers/nvdimm/nd-core.h
    +++ b/drivers/nvdimm/nd-core.h
    @@ -105,6 +105,8 @@ resource_size_t nd_pmem_available_dpa(st
    struct nd_mapping *nd_mapping, resource_size_t *overlap);
    resource_size_t nd_blk_available_dpa(struct nd_region *nd_region);
    resource_size_t nd_region_available_dpa(struct nd_region *nd_region);
    +int nd_region_conflict(struct nd_region *nd_region, resource_size_t start,
    + resource_size_t size);
    resource_size_t nvdimm_allocated_dpa(struct nvdimm_drvdata *ndd,
    struct nd_label_id *label_id);
    int alias_dpa_busy(struct device *dev, void *data);
    --- a/drivers/nvdimm/pfn_devs.c
    +++ b/drivers/nvdimm/pfn_devs.c
    @@ -589,14 +589,47 @@ static u64 phys_pmem_align_down(struct n
    ALIGN_DOWN(phys, nd_pfn->align));
    }

    +/*
    + * Check if pmem collides with 'System RAM', or other regions when
    + * section aligned. Trim it accordingly.
    + */
    +static void trim_pfn_device(struct nd_pfn *nd_pfn, u32 *start_pad, u32 *end_trunc)
    +{
    + struct nd_namespace_common *ndns = nd_pfn->ndns;
    + struct nd_namespace_io *nsio = to_nd_namespace_io(&ndns->dev);
    + struct nd_region *nd_region = to_nd_region(nd_pfn->dev.parent);
    + const resource_size_t start = nsio->res.start;
    + const resource_size_t end = start + resource_size(&nsio->res);
    + resource_size_t adjust, size;
    +
    + *start_pad = 0;
    + *end_trunc = 0;
    +
    + adjust = start - PHYS_SECTION_ALIGN_DOWN(start);
    + size = resource_size(&nsio->res) + adjust;
    + if (region_intersects(start - adjust, size, IORESOURCE_SYSTEM_RAM,
    + IORES_DESC_NONE) == REGION_MIXED
    + || nd_region_conflict(nd_region, start - adjust, size))
    + *start_pad = PHYS_SECTION_ALIGN_UP(start) - start;
    +
    + /* Now check that end of the range does not collide. */
    + adjust = PHYS_SECTION_ALIGN_UP(end) - end;
    + size = resource_size(&nsio->res) + adjust;
    + if (region_intersects(start, size, IORESOURCE_SYSTEM_RAM,
    + IORES_DESC_NONE) == REGION_MIXED
    + || !IS_ALIGNED(end, nd_pfn->align)
    + || nd_region_conflict(nd_region, start, size + adjust))
    + *end_trunc = end - phys_pmem_align_down(nd_pfn, end);
    +}
    +
    static int nd_pfn_init(struct nd_pfn *nd_pfn)
    {
    u32 dax_label_reserve = is_nd_dax(&nd_pfn->dev) ? SZ_128K : 0;
    struct nd_namespace_common *ndns = nd_pfn->ndns;
    - u32 start_pad = 0, end_trunc = 0;
    + struct nd_namespace_io *nsio = to_nd_namespace_io(&ndns->dev);
    resource_size_t start, size;
    - struct nd_namespace_io *nsio;
    struct nd_region *nd_region;
    + u32 start_pad, end_trunc;
    struct nd_pfn_sb *pfn_sb;
    unsigned long npfns;
    phys_addr_t offset;
    @@ -628,30 +661,7 @@ static int nd_pfn_init(struct nd_pfn *nd

    memset(pfn_sb, 0, sizeof(*pfn_sb));

    - /*
    - * Check if pmem collides with 'System RAM' when section aligned and
    - * trim it accordingly
    - */
    - nsio = to_nd_namespace_io(&ndns->dev);
    - start = PHYS_SECTION_ALIGN_DOWN(nsio->res.start);
    - size = resource_size(&nsio->res);
    - if (region_intersects(start, size, IORESOURCE_SYSTEM_RAM,
    - IORES_DESC_NONE) == REGION_MIXED) {
    - start = nsio->res.start;
    - start_pad = PHYS_SECTION_ALIGN_UP(start) - start;
    - }
    -
    - start = nsio->res.start;
    - size = PHYS_SECTION_ALIGN_UP(start + size) - start;
    - if (region_intersects(start, size, IORESOURCE_SYSTEM_RAM,
    - IORES_DESC_NONE) == REGION_MIXED
    - || !IS_ALIGNED(start + resource_size(&nsio->res),
    - nd_pfn->align)) {
    - size = resource_size(&nsio->res);
    - end_trunc = start + size - phys_pmem_align_down(nd_pfn,
    - start + size);
    - }
    -
    + trim_pfn_device(nd_pfn, &start_pad, &end_trunc);
    if (start_pad + end_trunc)
    dev_info(&nd_pfn->dev, "%s alignment collision, truncate %d bytes\n",
    dev_name(&ndns->dev), start_pad + end_trunc);
    @@ -662,7 +672,7 @@ static int nd_pfn_init(struct nd_pfn *nd
    * implementation will limit the pfns advertised through
    * ->direct_access() to those that are included in the memmap.
    */
    - start += start_pad;
    + start = nsio->res.start + start_pad;
    size = resource_size(&nsio->res);
    npfns = PFN_SECTION_ALIGN_UP((size - start_pad - end_trunc - SZ_8K)
    / PAGE_SIZE);
    --- a/drivers/nvdimm/region_devs.c
    +++ b/drivers/nvdimm/region_devs.c
    @@ -1112,6 +1112,47 @@ int nvdimm_has_cache(struct nd_region *n
    }
    EXPORT_SYMBOL_GPL(nvdimm_has_cache);

    +struct conflict_context {
    + struct nd_region *nd_region;
    + resource_size_t start, size;
    +};
    +
    +static int region_conflict(struct device *dev, void *data)
    +{
    + struct nd_region *nd_region;
    + struct conflict_context *ctx = data;
    + resource_size_t res_end, region_end, region_start;
    +
    + if (!is_memory(dev))
    + return 0;
    +
    + nd_region = to_nd_region(dev);
    + if (nd_region == ctx->nd_region)
    + return 0;
    +
    + res_end = ctx->start + ctx->size;
    + region_start = nd_region->ndr_start;
    + region_end = region_start + nd_region->ndr_size;
    + if (ctx->start >= region_start && ctx->start < region_end)
    + return -EBUSY;
    + if (res_end > region_start && res_end <= region_end)
    + return -EBUSY;
    + return 0;
    +}
    +
    +int nd_region_conflict(struct nd_region *nd_region, resource_size_t start,
    + resource_size_t size)
    +{
    + struct nvdimm_bus *nvdimm_bus = walk_to_nvdimm_bus(&nd_region->dev);
    + struct conflict_context ctx = {
    + .nd_region = nd_region,
    + .start = start,
    + .size = size,
    + };
    +
    + return device_for_each_child(&nvdimm_bus->dev, &ctx, region_conflict);
    +}
    +
    void __exit nd_region_devs_exit(void)
    {
    ida_destroy(&region_ida);

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