[Qemu-devel] Super nested KVM

[Qemu-devel] Super nested KVM

[Richard W.M. Jones]

If you have odd Intel or AMD hardware, I'd appreciate if you could
test my disk image which recursively launches nested KVM until
something breaks:

  http://rwmj.wordpress.com/2014/07/03/super-nested-kvm/#content

FWIW:

* AMD FX(tm)-8320 Eight-Core Processor:

L3 guest fails to boot with

[   30.769000] BUG: unable to handle kernel NULL pointer dereference at 0000000000000180
[   30.769000] IP: [<ffffffff810be871>] __queue_work+0x41/0x4e0

* Intel(R) Core(TM) i7-2600K CPU @ 3.40GHz [Sandybridge]:

L4 guest either hangs very early in boot, or is so slow that it
makes no visible progress.

There's also a TCG-only mode, but the test ran so slowly as to be
inconclusive.  I might leave it going overnight.

Rich.

-- 
Richard Jones, Virtualization Group, Red Hat http://people.redhat.com/~rjones
Read my programming and virtualization blog: http://rwmj.wordpress.com
virt-builder quickly builds VMs from scratch
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Re: [Qemu-devel] Super nested KVM

[Richard W.M. Jones]

On Thu, Jul 03, 2014 at 06:34:33PM +0100, Richard W.M. Jones wrote:
> There's also a TCG-only mode, but the test ran so slowly as to be
> inconclusive.  I might leave it going overnight.

Well I got bored with the TCG test after about 4 hours.  It appears to
hang launching the L3 guest, reproducible on two different hosts both
running qemu 2.0.0.

Rich.

-- 
Richard Jones, Virtualization Group, Red Hat http://people.redhat.com/~rjones
Read my programming and virtualization blog: http://rwmj.wordpress.com
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Re: [Qemu-devel] Super nested KVM

[Vasiliy Tolstov]

2014-07-04 1:00 GMT+04:00 Richard W.M. Jones <rjones@redhat.com>:
> Well I got bored with the TCG test after about 4 hours.  It appears to
> hang launching the L3 guest, reproducible on two different hosts both
> running qemu 2.0.0.


In my tests qemu tcg sometimes fail when run first vm. (kernel 3.12)

-- 
Vasiliy Tolstov,
e-mail: v.tolstov@selfip.ru
jabber: vase@selfip.ru

Re: [Qemu-devel] Super nested KVM

[Richard W.M. Jones]

On Fri, Jul 04, 2014 at 04:17:11PM +0400, Vasiliy Tolstov wrote:
> 2014-07-04 1:00 GMT+04:00 Richard W.M. Jones <rjones@redhat.com>:
> > Well I got bored with the TCG test after about 4 hours.  It appears to
> > hang launching the L3 guest, reproducible on two different hosts both
> > running qemu 2.0.0.
> 
> 
> In my tests qemu tcg sometimes fail when run first vm. (kernel 3.12)

Does running a regular with TCG fail in the same way?

You can examine / adjust the parameters by editing the
run-supernested.sh script.  It runs qemu directly.

Rich.

-- 
Richard Jones, Virtualization Group, Red Hat http://people.redhat.com/~rjones
Read my programming and virtualization blog: http://rwmj.wordpress.com
virt-builder quickly builds VMs from scratch
http://libguestfs.org/virt-builder.1.html