Re: [Qemu-devel] [PATCH 0/5] vhost: enable for all targets

["Michael S. Tsirkin" <mst@redhat.com>]

On Tue, Nov 27, 2018 at 10:04:59AM +0100, Paolo Bonzini wrote:
> On 26/11/18 23:43, Michael S. Tsirkin wrote:
> > On Mon, Nov 26, 2018 at 02:20:38PM +0100, Paolo Bonzini wrote:
> >> vhost does not have to be supported only if KVM is present, in fact
> >> vhost-user does not even need any kind of kernel support.  This series
> >> changes this.  The rationale is that, when vhost-user-test.c will be
> >> converted to qgraph, it will be able to test vhost-user support
> >> for virtio-mmio backend even on x86.
> > 
> > The reason for limiting it to KVM was very simple:
> > it has the same set of problems with ordering
> > as mttcg.
> > 
> > So I guess it's fine but I think we must then limit it
> > to when tcg emits fence instructions.
> > 
> > Otherwise we'll get subtle race conditions.
> 
> Got it, I'll take a look.  However, right now you _can_ use vhost with
> tcg as long as e.g. qemu-system-x86_64 is compiled with KVM support, so
> this patch is not changing anything in this respect; the bug is
> independent of this series.
> 
> Paolo
> 

Well qemu built with KVM implies host architecture == guest
architecture, right? That should ensure race conditions do not happen in
a very hacky way.

-- 
MST