On Mon, Jan 23, 2017 at 09:57:23AM +0800, Jason Wang wrote: > > > On 2017年01月22日 17:09, Peter Xu wrote: > >On Sun, Jan 22, 2017 at 04:13:32PM +0800, Jason Wang wrote: > >> > >>On 2017年01月20日 21:08, Peter Xu wrote: > >>>Previous replay works for domain switch only if the original domain does > >>>not have mapped pages. For example, if we switch domain from A to B, it > >>>will only work if A has no existing mapping. If there is, then there's > >>>problem - current replay didn't make sure the old mappings are cleared > >>>before replaying the new one. > >>I'm not quite sure this is needed. I thought the only thing we need to do is > >>stop DMA of device during the moving? Or is there an example that will cause > >>trouble? > >I think this patch is essential. > > > >Example: > > > >- device D1 moved to domain A, domain A has no mapping > >- map page P1 in domain A, so D1 will have a mapping of page P1 > >- create domain B with mapping P2 > >- move D1 from domain A to domain B > > > >Here if we don't unmap existing pages in domain A (P1), > > I thought driver should do this work instead of device, because only driver > knows whether or not iova is still needed?
Do you mean "device driver" above? I don't know whether I understood the question above, but the problem should be there no matter which one is managing iova? Thanks, -- peterx
