Dan Williams dan.j.williams@intel.com writes:
Fix the NFIT parsing code to treat a 0 index in a SPA Range Structure as a special case and not match Region Mapping Structures that use 0 to indicate that they are not mapped. Without this fix some platform BIOS descriptions of "virtual disk" ranges do not result in the pmem driver attaching to the range.
Details: In addition to typical persistent memory ranges, the ACPI NFIT may also convey "virtual" ranges. These ranges are indicated by a UUID in the SPA Range Structure of UUID_VOLATILE_VIRTUAL_DISK, UUID_VOLATILE_VIRTUAL_CD, UUID_PERSISTENT_VIRTUAL_DISK, or UUID_PERSISTENT_VIRTUAL_CD. The critical difference between virtual ranges and UUID_PERSISTENT_MEMORY, is that virtual do not support associations with Region Mapping Structures. For this reason the "index" value of virtual SPA Range Structures is allowed to be 0. If a platform BIOS decides to represent unmapped
^^^^^^^^
NVDIMMs with a 0 index in their "SPA Range Structure Index" the driver
^^^^^^^
That language confused me. I thought you were talking about a separate issue, whereby NVDIMMs which are not mapped (probably due to some errors with the dimms themselves) would get an index of 0. But upon re-reading, I think you just meant that the virtual media is not mapped via a region mapping structure.
falsely matches them and may falsely require labels where "virtual disks" are expected to be label-less. I.e. label-less is where the namespace-range == region-range and the pmem driver attaches with no user action to create a namespace.
Cc: Jacek Zloch jacek.zloch@intel.com Cc: Lukasz Sobieraj lukasz.sobieraj@intel.com Cc: "Lee, Chun-Yi" jlee@suse.com Cc: stable@vger.kernel.org Fixes: c2f32acdf848 ("acpi, nfit: treat virtual ramdisk SPA as pmem region") Reported-by: Krzysztof Rusocki krzysztof.rusocki@intel.com Reported-by: Damian Bassa damian.bassa@intel.com Signed-off-by: Dan Williams dan.j.williams@intel.com
drivers/acpi/nfit/core.c | 2 ++ 1 file changed, 2 insertions(+)
diff --git a/drivers/acpi/nfit/core.c b/drivers/acpi/nfit/core.c index 23d9a09d7060..6f15e56ef955 100644 --- a/drivers/acpi/nfit/core.c +++ b/drivers/acpi/nfit/core.c @@ -3021,6 +3021,8 @@ static int acpi_nfit_register_region(struct acpi_nfit_desc *acpi_desc, struct acpi_nfit_memory_map *memdev = nfit_memdev->memdev; struct nd_mapping_desc *mapping;
if (memdev->range_index == 0 || spa->range_index == 0)continue;
The change looks good, but can you add a comment to the code? With that, you can add my:
Reviewed-by: Jeff Moyer jmoyer@redhat.com
Thanks! Jeff