Re: [Xen-devel] [PATCH RFC 00/39] x86/KVM: Xen HVM guest support

[Ankur Arora]

On 2/20/19 3:39 PM, Marek Marczykowski-GÃrecki wrote:
> On Wed, Feb 20, 2019 at 08:15:30PM +0000, Joao Martins wrote:
> >   2. PV Driver support (patches 17 - 39)
> >
> >   We start by redirecting hypercalls from the backend to routines
> >   which emulate the behaviour that PV backends expect i.e. grant
> >   table and interdomain events. Next, we add support for late
> >   initialization of xenbus, followed by implementing
> >   frontend/backend communication mechanisms (i.e. grant tables and
> >   interdomain event channels). Finally, introduce xen-shim.ko,
> >   which will setup a limited Xen environment. This uses the added
> >   functionality of Xen specific shared memory (grant tables) and
> >   notifications (event channels).
>
> Does it mean backends could be run in another guest, similarly as on
> real Xen? AFAIK virtio doesn't allow that as virtio backends need
I'm afraid not. For now grant operations (map/unmap) can only be done
by backends to the local KVM instance.

Ankur

> arbitrary write access to guest memory. But grant tables provide enough
> abstraction to do that safely.

>