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

[Paolo Bonzini]

Il 09/05/2013 10:54, liu ping fan ha scritto:
> On Thu, May 9, 2013 at 4:44 PM, Michael S. Tsirkin <address@hidden> wrote:
>> 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.
>>>
>>> Signed-off-by: Liu Ping Fan <address@hidden>
>>
>> Is this seen in testing, or are you describing a theorecitical
>> scenario? Please make this clear in the commit log.
>>
> A  theorecitical scenario.  I think vcpu thread and vhost are async,
> so we need this method to sync.

But why should this matter for hostmem?  It doesn't communicate in any
way with the hypervisor.

Paolo