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 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; if (memdev->range_index != spa->range_index) continue; if (count >= ND_MAX_MAPPINGS) {
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
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 NVDIMMs with disconnected "Region Mapping Structures" (range-index == 0), the kernel may falsely associate them with standalone ranges where the "SPA Range Structure Index" is also zero. When this happens the driver 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 Reviewed-by: Jeff Moyer jmoyer@redhat.com Signed-off-by: Dan Williams dan.j.williams@intel.com --- Changes since v1: - Clarify the changelog (Jeff) - Add a comment about why range_index is checked (Jeff)
drivers/acpi/nfit/core.c | 3 +++ 1 file changed, 3 insertions(+)
diff --git a/drivers/acpi/nfit/core.c b/drivers/acpi/nfit/core.c index 23d9a09d7060..a3ef6cce644c 100644 --- a/drivers/acpi/nfit/core.c +++ b/drivers/acpi/nfit/core.c @@ -3021,6 +3021,9 @@ 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;
+ /* range index 0 == unmapped in SPA or invalid-SPA */ + if (memdev->range_index == 0 || spa->range_index == 0) + continue; if (memdev->range_index != spa->range_index) continue; if (count >= ND_MAX_MAPPINGS) {
linux-stable-mirror@lists.linaro.org
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Dan Williams -
Jeff Moyer