On 17/05/18 14:10, Jonathan Cameron wrote: > On Fri, 11 May 2018 20:06:03 +0100 > Jean-Philippe Brucker <jean-philippe.brucker@xxxxxxx> wrote: > >> Add bind() and unbind() operations to the IOMMU API. Bind() returns a >> PASID that drivers can program in hardware, to let their devices access an >> mm. This patch only adds skeletons for the device driver API, most of the >> implementation is still missing. >> >> IOMMU groups with more than one device aren't supported for SVA at the >> moment. There may be P2P traffic between devices within a group, which >> cannot be seen by an IOMMU (note that supporting PASID doesn't add any >> form of isolation with regard to P2P). Supporting groups would require >> calling bind() for all bound processes every time a device is added to a >> group, to perform sanity checks (e.g. ensure that new devices support >> PASIDs at least as big as those already allocated in the group). > > Is it worth adding an explicit comment on this reasoning (or a minimal subset > of it) at the check for the number of devices in the group? > It's well laid out here, but might not be so obvious if someone is reading > the code in the future. Sure, I'll add something Thanks, Jean
