On Tue, May 2, 2017 at 9:30 AM, Auger Eric <eric.auger@xxxxxxxxxx> wrote: > Hi Will, Robin, Jean-Philippe, > > I have been working on the integration between user-space emulated > SMMU-v3 and VFIO in QEMU. At the moment I fail identifying a proper easy > way to trap page table updates. This is requested to keep the host > translation structures consistent to guest translation structures. > > On Intel VTD there is a so-called "caching mode" (CM, see VTD spec > paragraph 6.1) that forces the OS to explicitly invalidate caches > whenever it updates any remapping structure (updates to not-present or > present entries). Those invalidation commands are used to trap and > update host structures. This mode was devised for virtualization. I was > not able to find such "caching mode" on ARM SMMU. Is there any? > > If not, do you have any other suggestion, I mean, besides the > virtio-based solution. > > Worst case, can you make the guest page tables read-only and catch the faults and propagate changes to SMMU translations? -Christoffer
