On Thu, 2016-03-03 at 13:53 -0800, Dan Williams wrote:
> On a platform where 'Persistent Memory' and 'System RAM' are mixed
> within a given sparsemem section, trim the namespace and notify about the
> sub-optimal alignment.
>
> Cc: Toshi Kani <toshi.kani@xxxxxxx>
> Cc: Ross Zwisler <ross.zwisler@xxxxxxxxxxxxxxx>
> Signed-off-by: Dan Williams <dan.j.williams@xxxxxxxxx>
> ---
> drivers/nvdimm/namespace_devs.c | 7 ++
> drivers/nvdimm/pfn.h | 10 ++-
> drivers/nvdimm/pfn_devs.c | 5 ++
> drivers/nvdimm/pmem.c | 125 ++++++++++++++++++++++++++++-----
> ------
> 4 files changed, 111 insertions(+), 36 deletions(-)
>
> diff --git a/drivers/nvdimm/namespace_devs.c
> b/drivers/nvdimm/namespace_devs.c
> index 8ebfcaae3f5a..463756ca2d4b 100644
> --- a/drivers/nvdimm/namespace_devs.c
> +++ b/drivers/nvdimm/namespace_devs.c
> @@ -133,6 +133,7 @@ bool nd_is_uuid_unique(struct device *dev, u8 *uuid)
> bool pmem_should_map_pages(struct device *dev)
> {
> struct nd_region *nd_region = to_nd_region(dev->parent);
> + struct nd_namespace_io *nsio;
>
> if (!IS_ENABLED(CONFIG_ZONE_DEVICE))
> return false;
> @@ -143,6 +144,12 @@ bool pmem_should_map_pages(struct device *dev)
> if (is_nd_pfn(dev) || is_nd_btt(dev))
> return false;
>
> + nsio = to_nd_namespace_io(dev);
> + if (region_intersects(nsio->res.start, resource_size(&nsio-
> >res),
> + IORESOURCE_SYSTEM_RAM,
> + IORES_DESC_NONE) == REGION_MIXED)
Should this be != REGION_DISJOINT for safe?
> + return false;
> +
:
> @@ -304,21 +311,56 @@ static int nd_pfn_init(struct nd_pfn *nd_pfn)
> }
>
> memset(pfn_sb, 0, sizeof(*pfn_sb));
> - npfns = (pmem->size - SZ_8K) / SZ_4K;
> +
> + /*
> + * 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) {
> + size = resource_size(&nsio->res);
> + end_trunc = start + size - PHYS_SECTION_ALIGN_DOWN(start
> + size);
> + }
This check seems to assume that guest's regular memory layout does not
change. That is, if there is no collision at first, there won't be any
later. Is this a valid assumption?
Thanks,
-Toshi
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