Ok, so I searched for the patch to Xen mentioned in the upstream discussion which was:
x86: Mask X86_FEATURE_XSAVE in cpuid leaf 1, ecx, as we don't allow guests to use it (by setting cr4.OSXSAVE). Together with the other comments I think I understand now that Xen always has masked off OSXSAVE in the cpuid bits but not XSAVE. And the newer kernel patch checks for OSXSAVE which is safe. Xen will set OSXSAVE (together with XSAVE) in cpuid bits if it supports it and allows the guest to use it, too. -- You received this bug notification because you are a member of Ubuntu Bugs, which is subscribed to Ubuntu. https://bugs.launchpad.net/bugs/1044550 Title: Update the EC2 work-around for the OSXSAVE issue in pv-ops To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/linux/+bug/1044550/+subscriptions -- ubuntu-bugs mailing list ubuntu-bugs@lists.ubuntu.com https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs
