Re: [Qemu-devel] [PATCH 00/22] QAPI Round 1

[Anthony Liguori <anthony@codemonkey.ws>]

On 03/08/2011 08:17 AM, Avi Kivity wrote:
>> No, I'm in the process of writing up my latest proposal.
>>
>> The idea is pretty simple.  QAPI generates code for libqmp that takes 
>> native arguments for a command and generates a QObject.  It also 
>> generates code for QEMU that takes a QObject and generates native 
>> arguments to pass to a function.
>>
>> For guest commands, we combine the two such that we unmarshal the 
>> incoming QObject to native arguments, then pass it to another 
>> function that marshals the arguments to a QObject.  The QObject is 
>> then passed to the guest-agent which uses the same generated code as 
>> QEMU to unmarshal the qobject to native arguments and dispatch to a 
>> function.
>>
>> That means the only new code we need for the guest agent is the 
>> JSON-over-virtio-serial transport.  To implement guest commands, we 
>> just add the command to the schema, implement the native arguments 
>> version in guest-agent, and that's it.
>>
>> QEMU will buffer all input and output to the guest acting as a first 
>> line of defence from a security PoV.  That means that the guest 
>> doesn't get to talk directly to the management tools which removes 
>> that as a direct attack surface.
>>
>> The nature of QEMU is such that if we do tagging correctly, we can 
>> also support live migration transparently to the guest too.
>

http://wiki.qemu.org/Features/QAPI/GuestAgent

Regards,

Anthony Liguori