On Wed, Jan 03, 2024 at 12:01:08PM -0400, Jason Gunthorpe wrote: > On Wed, Jan 03, 2024 at 10:24:42AM +0800, Yi Liu wrote: > > On 2024/1/3 07:38, Jason Gunthorpe wrote: > > > On Fri, Dec 15, 2023 at 12:01:19PM +0800, Yi Liu wrote: > > > > > I think I misread Yi's narrative: dev_id is a working approach > > > > > for VMM to convert to a vRID, while he is asking for a better > > > > > alternative :) > > > > > > > > In concept, dev_id works, but in reality we have problem to get a dev_id > > > > for a given device in intel iommu driver, hence I'm asking for help here. :) > > > > > > I think we just need to solve this one way or another.. Even if you > > > use a viommu object you still end up having difficult coupling to > > > iommufd > > > > > > Some: > > > iommufd_get_dev_id(struct iommufd_ctx *ictx, struct device *dev) > > > > > > Callable by a driver (using the driver-callable function > > > infrastructure we made for dirty tracking) Is really all that is > > > needed here. > > > > yep, I noticed IOMMUFD_DRIVER was selected by intel iommu driver when > > IOMMUFD is configed. Maybe such an API could be compiled when > > IOMMUFD_DRIVER is enabled as well. This does address my concern on making > > intel iommu driver depending on iommufd. But still need a way to pass in > > the iommufd_ctx pointer to intel iommu driver, and store it. Hence intel > > iommu driver could call the above iommufd_get_dev_id(). One possible way is > > passing it when attaching device to domain and clear it in detach. However, > > this seems not ideal as iommufd_ctx information should be static between > > bind_iommufd and unbind. But we don't call into intel iommu driver in the > > bind and unbind operations. May need to add new iommu op. Any suggestion > > here? > > You can pass the ctx to the invalidate op, it is already implied > because the passed iommu_domain is linked to a single iommufd ctx. The device virtual id lookup API needs something similar, yet it likely needs a viommu pointer (or its id) instead? As the table is attached to a viommu while an ictx can have multiple viommus, right? Thanks Nic
