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 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 <[email protected]> Cc: Lukasz Sobieraj <[email protected]> Cc: "Lee, Chun-Yi" <[email protected]> Cc: <[email protected]> Fixes: c2f32acdf848 ("acpi, nfit: treat virtual ramdisk SPA as pmem region") Reported-by: Krzysztof Rusocki <[email protected]> Reported-by: Damian Bassa <[email protected]> Signed-off-by: Dan Williams <[email protected]> --- 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; if (memdev->range_index != spa->range_index) continue; if (count >= ND_MAX_MAPPINGS) {
