Attention amd vfio users do not update your bios

Operating Systems & Open Source Virtualization
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100

Another data point:

System:

  • Ryzen 3700X
  • X470 Taichi
  • BIOS 3.77 (beta) with AGESA Combo-AM4 1.0.0.4 Patch B
  • Linux kernel 5.3, no ACS or PCI 127 bug patches

Results:

  • improved IOMMU separation of devices attached to the chipset (USB, audio and SATA)
  • no Unknown PCI header type ‘127’ issues, allowing VMs to be stopped/started multiple times without the host being rebooted.

Conclusion

  • AGESA Combo-AM4 1.0.0.4 Patch B fixes issues faced previously (YMMV)
  • Many vendors have already released BIOSes with this AGESA version for some/all of their motherboards (still waiting on ASRock to release a non-beta version for the X470 Taichi)
  • If the option is available for your motherboard, it might be worth upgrading (again, YMMV)
  • AMD/vendors could potentially break all of this in the future (but that’s a story for another day)

IOMMU groups available here