nested kvm fails with trusty and upstream kernels
Affects | Status | Importance | Assigned to | Milestone | |
---|---|---|---|---|---|
linux (Ubuntu) |
Fix Released
|
Medium
|
Unassigned | ||
Trusty |
Fix Released
|
Medium
|
Unassigned |
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://
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.
Changed in linux (Ubuntu): | |
importance: | Undecided → Medium |
tags: | added: kernel-da-key |
tags: | removed: kernel-da-key |
summary: |
- nested kvm fails with trust and upstream kernels + nested kvm fails with trusty and upstream kernels |
Changed in linux (Ubuntu Trusty): | |
status: | Confirmed → Fix Committed |
This bug is missing log files that will aid in diagnosing the problem. From a terminal window please run:
apport-collect 1278531
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This change has been made by an automated script, maintained by the Ubuntu Kernel Team.