Re: [Qemu-devel] [RFC][PATCH v6 00/23] virtagent: host/guest RPC communication agent

[Dor Laor <dlaor@redhat.com>]

On 02/17/2011 10:26 AM, Jes Sorensen wrote:
> On 02/16/11 18:22, Michael Roth wrote:
>> We've seen similar behavior. I think it comes down to qemu-va being
>> linked against shared objects in the host that don't necessarily
>> coincide with what's in the guest. It's somewhat misleading that we
>> currently build qemu-va along with the binary, since qemu-va is not
>> meant to be used on the host, and the version built on the host is not
>> meant to be used in the guest.
>>
>> Really the guest binary, qemu-va, should be built in a proper build
>> environment for that particular guest. Long term it may make sense to
>> have a "guest-utils" target that isn't part of the normal host-build
>> process to reflect binaries with these kinds of requirements. For now I
>> think we'll may just end up removing qemu-va from the default make
>> target, and only build it explicitly with "make qemu-va".
>
> Hi Michael,
>
> I am not sure I was totally clear in my mail, but the crashes I saw were
> QEMU on the host that went down. Not qemu-va running in the guest. My
> worry is that we are adding a lot of complexity into QEMU on the host
> side which is going to be difficult to audit, especially with things
> like the HTML and XML processing. If we separated host side processing
> into a separate command, we could better protect ourselves against a
> situation where a rogue guest could kill QEMU and possibly exploit it on
> the host side. I think we should seriously look at moving the agent
> processing code out of main QEMU and into a standalone command, maybe
> qemu-va-host or something like that.

+1
Qemu will fork this qemu-va-host process so it won't be an extra burden 
on the management, qemu and his son should talk over pipe, passing the 
qmp commands to it.

>
> There has been talk about doing the same thing with the monitor in the
> past, and have it talk to the main QEMU process over QMP. This pretty
> much goes along the same lines, except that I think we need the XML
> handling moved out with it, so we couldn't just layer it directly on top
> of QMP.
>
>> P.S. Hoping to have the execute-RPCs-in-seperate-threads work done soon
>> so we can get back to integrating your patches.
>
> Sounds good!
>
> Cheers,
> Jes
>