On 19.06.2013, at 06:59, Benjamin Herrenschmidt wrote: > On Wed, 2013-06-19 at 13:05 +0930, Rusty Russell wrote: >> symbol_get() won't try to load a module; it'll just fail. This is what >> you want, since they must have vfio in the kernel to get a valid fd... > > Ok, cool. I suppose what we want here Alexey is slightly higher level, > something like: > > vfio_validate_iommu_id(file, iommu_id) > > Which verifies that the file that was passed in is allowed to use > that iommu_id. > > That's a simple and flexible interface (ie, it will work even if we > support multiple iommu IDs in the future for a vfio, for example > for DDW windows etc...), the logic to know about the ID remains > in qemu, this is strictly a validation call. > > That way we also don't have to expose the containing vfio struct etc... > just that simple function. > > Alex, any objection ? Which Alex? :) I think validate works, it keeps iteration logic out of the kernel which is a good thing. There still needs to be an interface for getting the iommu id in VFIO, but I suppose that one's for the other Alex and Jörg to comment on. > > Do we need to make it a get/put interface instead ? > > vfio_validate_and_use_iommu(file, iommu_id); > > vfio_release_iommu(file, iommu_id); > > To ensure that the resource remains owned by the process until KVM > is closed as well ? > > Or do we want to register with VFIO with a callback so that VFIO can > call us if it needs us to give it up ? Can't we just register a handler on the fd and get notified when it closes? Can you kill VFIO access without closing the fd? Alex -- To unsubscribe from this list: send the line "unsubscribe kvm" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
