File System Gets Corrupted On Disks Connected to H330 PERC On Dell EMC AMD Based Servers

• Update BIOS to 1.8.7 or latest which will mark the PERC H330 address range as Unity mapping.
• Kernel fix is in progress. Fix details will be updated here.

Note that either kernel update or BIOS update should be enough to fix the issue. Updating both is not mandatory.

PERC H330 controllers do not have their own memory and have to use system memory for RAID operations. So, BIOS will reserve a memory range and report it as an “exclusion range” and mark it reserved in the IVRS table so that amd_iommu driver will set the exclusion range registers in the IOMMU, which will disable IOMMU to that particular region of memory. There are two reasons that would lead to the data corruption:

  1) The exclusion range is not reserved in the IOVA Domain of PERC H330 and are used for DMA, resulting in data corruption.

  2) IVRS Table in BIOS provides the starting address and length of the exclusion range for H330. While AMD IOMMU driver is setting up exclusion range, the driver is adding the IVRS provided starting address and length to get the ending address that it uses to program the exclusion range limit register in the IOMMU, but to get the ending address it should add the length to the starting address and subtract one, which results in the exclusion range excluding one page extra past the end of the BIOS specified exclusion range.  If the kernel uses this extra page address as IOVA, then it leads to data corruption.