I've managed to verify this on kernel 4.4.0-143-generic, the problem isn't reproducible anymore.
Worth noticing that when using the kernel 4.4.0-143 in both host and guest, we cannot change MSR bit anymore from within the guest, so the performance drop is not observed. ** Tags removed: verification-needed-xenial ** Tags added: verification-done-xenial -- You received this bug notification because you are a member of Ubuntu Bugs, which is subscribed to Ubuntu. https://bugs.launchpad.net/bugs/1764956 Title: Guests using IBRS incur a large performance penalty To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/linux/+bug/1764956/+subscriptions -- ubuntu-bugs mailing list [email protected] https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs
