9 Replies Latest reply on Sep 23, 2018 2:08 AM by abucodonosor

    Threadripper/MSI: BIOS advertising SEV support, even if the CPU does not support it (breaks kvm on Linux)

    mmusenbr

      I'm running an AMD Ryzen Threadripper 1920X CPU on a MSI X399 Gaming PRO Carbon board on Linux (Debian unstable, Linux kernel 4.17.17-1 from Debian)
      After the upgrade to the latest available MSI BIOS which includes the AGESA Code 1.1.01A I ran into different problems on a linux system (udev timeout, kvm module does not load).

      As from other bugreports [1] this problem seems not related to MSI, so it looks like an issue in the AGESA code.

      The source of the issue seems to be that the CPU/BIOS advertises SEV support even if it does not.

       

      According to the AMD docs [2], the EAX register in 0x8000001f holds the information about the support for SME (bit 0), SEV (bit 1), VmPageFlush (bit 2) and SevEs (bit 3).

      With the command 'x86info -r | grep 0x8000001f' I see the content of the EAX register is set to 0x7. Which I read as support for SME, SEV and VmPageFlush.

      But apperantly AMD Threadripper family does not support SEV.

       

      Additionally what I read the requirement comes from AGESA (please confirm): It is currently officially not possible to downgrade BIOSes running newer AGESA codes, which means that if a new BIOS update breaks something, the user is stuck until a new BIOS update fixing the issue is released.

       

      Kind Regards Michael Musenbrock

       

      PS: I already forwarded the issue to MSI, but as I did not find the report either on a MSI nor on a official AMD site, I wanted to add it to the support forum

       

      [1] https://bugzilla.redhat.com/show_bug.cgi?id=1608242

      [2] Open-Source Register Reference For AMD Family 17h Processors Models 00h-2Fh: https://developer.amd.com/wp-content/resources/56255_3_03.PDF