Re: [Xen-devel] Status of Nested Virt in 4.4 (Was: Re: Xen 4.4 development update)

[Ian Campbell <Ian.Campbell@xxxxxxxxxx>]

On Fri, 2014-01-24 at 15:56 +0100, Tim Deegan wrote:
> B11;rgb:0000/0000/0000At 14:47 +0000 on 24 Jan (1390571231), George Dunlap 
> wrote:
> > On 01/17/2014 09:40 AM, Ian Campbell wrote:
> > > On Fri, 2014-01-17 at 02:16 +0000, Zhang, Yang Z wrote:
> > >> As Andrew said, nested still in experimental stage, because there are
> > >> still lots of scenarios I am not covered in my testing. So it may not
> > >> accurate to say it is good supported. But I hope people know that the
> > >> nested is ready to use now. And encourage them to try it and report
> > >> bug to us to push nested move forward.
> > > Perhaps we could say it is "tech preview" rather than "experimental"?
> > 
> > If { {xp,win7,win8,rhel6}x{x86,x64} } x { Xen, KVM, VMWare } and Win7 XP 
> > compatibility mode are tested regularly, and only HyperV, L2 shadow, and 
> > paging / PoD don't work, I think we should be able to call this a "1.0" 
> > release for nested virt.  Then we can add in "now works with HyperV", 
> > "Now works with shadow", "Now works with paging" as those become mature.
> 
> That depends on what the failure modes are for the other cases --
> esp. given that the L1 guest's choice of hypervisor, shadow vs HAP &c,
> are not under the control of the L0 admin.  I thikn that has to be
> clearly understood before we encourage people to turn this on.

Especially in the light of the previous two bugs here which let the
guest admin crash the host, in at least one of the two cases even if the
host admin had disabled nested virt for that guest (and I think it was
actually in both cases...)

Ian.


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