Some information that I got while discussion this upstream: This is a problem with Xen. In fact the same flags get used when doing a bare metal boot. The explanation for the different behaviour is that Xen does use paging even in non-paging mode of the guest (just a identity mapped table). SMEP would be ignored in real non-paging mode but in the Xen case it is used but the pages are not set up correctly.
Right now this can be worked-around by using "smep=0" as a hypervisor boot argument, or "nosmep" on the grub command line of the guest. There was already a change that fixes a similar issue but in my testing it seems not to be in effect for this problem. -- You received this bug notification because you are a member of Ubuntu Bugs, which is subscribed to Ubuntu. https://bugs.launchpad.net/bugs/1157757 Title: [Regression] Stuck CPU1-x when booting as Xen HVM guest on certain Intel hosts To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/linux/+bug/1157757/+subscriptions -- ubuntu-bugs mailing list [email protected] https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs
