Note that "what we can do about saucy" - I don't really care, except in as much as debugging it will help to fix it in trusty.
You said: >From your description it sounds like some nested VMX (again) but just to make >sure I got this right. The failing combination is: > - Host: P user-space, T kernel; Lvl1: P user-space, P kernel; Lvl2: T > user-space, T kernel -> Host: T user-space, T kernel; Lvl1: T user-space, T kernel; Lvl2: T user-space, T kernel Right, except that Lvl2 can be anything. precise, quantal trusty, all fail, all in the same way, in lvl2. So the point is that levels 1 and 2 don't matter, nor does the qemu userspace on the host. Only the host kernel matters. -- You received this bug notification because you are a member of Kernel Packages, which is subscribed to linux in Ubuntu. https://bugs.launchpad.net/bugs/1278531 Title: nested kvm fails with trust and upstream kernels Status in “linux” package in Ubuntu: Confirmed Bug description: First: the 3.2 precise kernel handled nested qemu very well. As of saucy it has declined. In a host with saucy kernel (even on precise userspace), attempts to do nested kvm result in a hung kvm (inside the guest - host proceeds ok) taking 100%cpu. In a host with trusty kernel (even on precise userspace), nested kvm fails get past grub. I have two screenshots, one resulting from attempting to boot from a precise mini-iso, another from attempting to boot a cloud image at: http://cloud-images.ubuntu.com/quantal/current /quantal-server-cloudimg-amd64-disk1.img. (If you convert that image to raw, it fails the same way). On the host, I see the following in /var/log/kern.log: kvm: zapping shadow pages for mmio generation wraparound I've reproduced this both on (a) a intel based vostro laptop - with separate installs of precise and saucy (with ubuntu precise, saucy, trust, upstream kernels), (b) an intel based server with precise userspace and saucy and trusty kernels; and (c) an intel laptop running full uptodate trusty. As nested qemu worked will in the previous LTS, I think it is important to have it working in 14.04 LTS. ============= Original description ================ I have a precise host with saucy ubuntu kernel installed. I installed two VMs there, a saucy and a trusty guest. In the saucy guest, non-accelerated qemu works fine, but accelerated kvm hangs the first-level saucy guest completely, and pins it at 200% cpu usage: qemu-system-x86 --enable-kvm -monitor stdio -vnc :1 On the trusty guest it works just fine. To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/linux/+bug/1278531/+subscriptions -- Mailing list: https://launchpad.net/~kernel-packages Post to : kernel-packages@lists.launchpad.net Unsubscribe : https://launchpad.net/~kernel-packages More help : https://help.launchpad.net/ListHelp
