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

[Paolo Bonzini]

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