Re: [Qemu-devel] [PATCH 1/2] Vring: vring's listener's priority should higher than kvm

[Stefan Hajnoczi]

On Thu, May 09, 2013 at 08:40:21AM +0800, Liu Ping Fan wrote:
> From: Liu Ping Fan <address@hidden>
> 
> Hosts threads which handle vring should have high MemoryListener priority
> than kvm. For currently code, take the following scenario:
>   kvm_region_add() run earlier before vhost_region_add(), then in guest,
> vring's desc[i] can refer to addressX in the new region known by guest.
> But vhost does not know this new region yet, and the vring handler will
> fail.

Is there a concrete scenario where this happens?

I can think of situations like the ioeventfd being readable before
vhost/hostmem is populated.  But I don't see how that's related to the
priority of kvm_region_add().

Stefan