On 18.02.20 04:36, Tian, Kevin wrote: >> From: Christian Borntraeger >> Sent: Friday, February 7, 2020 7:39 PM >> >> From: Claudio Imbrenda <imbrenda@xxxxxxxxxxxxx> >> >> With the introduction of protected KVM guests on s390 there is now a >> concept of inaccessible pages. These pages need to be made accessible >> before the host can access them. >> >> While cpu accesses will trigger a fault that can be resolved, I/O >> accesses will just fail. We need to add a callback into architecture >> code for places that will do I/O, namely when writeback is started or >> when a page reference is taken. > > What about hooking the callback to DMA API ops? Not all device drivers do use the DMA API so it wont work for us.
