I re-checked all that you and I found, lets write a List with all that we know if there are patterns.
Host (should not matter, but be rather new) - in my case B4.18 Q2.11 For new qemu I'm using Mitaka. In this case being from https://launchpad.net/~ubuntu-cloud-archive/+archive/ubuntu/mitaka-staging to get those libvirt/qemu with the MDS fixes which are still waiting to be released. The check is like: $ uname -r; cat /sys/devices/system/cpu/vulnerabilities/mds; cat /proc/cpuinfo | grep -e ^bug -e ^flags | grep md An example result would look like a) 4.4.0-148-generic b) Mitigation: Clear CPU buffers; SMT Host state unknown c) flags : [...] md_clear d) bugs : cpu_meltdown spectre_v1 spectre_v2 spec_store_bypass l1tf mds a) to verify the kernel level is as expected b) to show what the kernel thinks about the Mitigation status c) check the md_clear in cpu flags d) show bugs the cpu is affected (not present on 3.13) Only if all those above are ok we call it good, otherwise add a comment what fails Test list: lvl 1 kernel T3.13 / T4.4 lvl 2 kernel T3.13 / T4.4 / B4.15 Qemu T2.0 / M2.5 T LVL1 LVL2 Result 01 T3.13 / Q2.0 T3.13 ok 02 T3.13 / Q2.0 T4.4 ok 03 T3.13 / Q2.0 B4.15 full passthrough crashes, md-clear feature not passed 04 T3.13 / Q2.5 T3.13 ok 05 T3.13 / Q2.5 T4.4 ok 06 T3.13 / Q2.5 B4.15 ok 07 T4.4 / Q2.0 T3.13 shows not-affected, md-clear available 08 T4.4 / Q2.0 T4.4 shows not-affected, md-clear available 09 T4.4 / Q2.0 B4.15 shows not-affected, md-clear available 10 T4.4 / Q2.5 T3.13 ok 11 T4.4 / Q2.5 T4.4 ok 12 T4.4 / Q2.5 B4.15 ok Of these testcases we have two fields of errors. #03 : base Trusty with a rather new guest having issues Fix to that seems to be in the kernel as 3.13 -> 4.4 fixes it #07-09: The qemu 2.0 in trusty seems to have issues if used with the HWE 4.4 kernel The fix to that seems to be in a newer qemu as 2.0 -> 2.5 fixes it ** Changed in: qemu (Ubuntu) Status: New => Confirmed -- You received this bug notification because you are a member of Ubuntu Bugs, which is subscribed to Ubuntu. https://bugs.launchpad.net/bugs/1829555 Title: nested virtualization w/first level trusty guests has odd MDS behavior To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/linux/+bug/1829555/+subscriptions -- ubuntu-bugs mailing list [email protected] https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs
