Hi Jason, On 12/8/21 1:56 PM, Jason Gunthorpe wrote: > On Wed, Dec 08, 2021 at 08:33:33AM +0100, Eric Auger wrote: >> Hi Baolu, >> >> On 12/8/21 3:44 AM, Lu Baolu wrote: >>> Hi Eric, >>> >>> On 12/7/21 6:22 PM, Eric Auger wrote: >>>> On 12/6/21 11:48 AM, Joerg Roedel wrote: >>>>> On Wed, Oct 27, 2021 at 12:44:20PM +0200, Eric Auger wrote: >>>>>> Signed-off-by: Jean-Philippe Brucker<jean-philippe.brucker@xxxxxxx> >>>>>> Signed-off-by: Liu, Yi L<yi.l.liu@xxxxxxxxxxxxxxx> >>>>>> Signed-off-by: Ashok Raj<ashok.raj@xxxxxxxxx> >>>>>> Signed-off-by: Jacob Pan<jacob.jun.pan@xxxxxxxxxxxxxxx> >>>>>> Signed-off-by: Eric Auger<eric.auger@xxxxxxxxxx> >>>>> This Signed-of-by chain looks dubious, you are the author but the last >>>>> one in the chain? >>>> The 1st RFC in Aug 2018 >>>> (https://lists.cs.columbia.edu/pipermail/kvmarm/2018-August/032478.html) >>>> said this was a generalization of Jacob's patch >>>> >>>> >>>> [PATCH v5 01/23] iommu: introduce bind_pasid_table API function >>>> >>>> >>>> >>>> https://lists.linuxfoundation.org/pipermail/iommu/2018-May/027647.html >>>> >>>> So indeed Jacob should be the author. I guess the multiple rebases got >>>> this eventually replaced at some point, which is not an excuse. Please >>>> forgive me for that. >>>> Now the original patch already had this list of SoB so I don't know if I >>>> shall simplify it. >>> As we have decided to move the nested mode (dual stages) implementation >>> onto the developing iommufd framework, what's the value of adding this >>> into iommu core? >> The iommu_uapi_attach_pasid_table uapi should disappear indeed as it is >> is bound to be replaced by /dev/iommu fellow API. >> However until I can rebase on /dev/iommu code I am obliged to keep it to >> maintain this integration, hence the RFC. > Indeed, we are getting pretty close to having the base iommufd that we > can start adding stuff like this into. Maybe in January, you can look > at some parts of what is evolving here: > > https://github.com/jgunthorpe/linux/commits/iommufd > https://github.com/LuBaolu/intel-iommu/commits/iommu-dma-ownership-v2 > https://github.com/luxis1999/iommufd/commits/iommufd-v5.16-rc2 Interesting. thank you for the preview links. I will have a look asap Eric > > From a progress perspective I would like to start with simple 'page > tables in userspace', ie no PASID in this step. > > 'page tables in userspace' means an iommufd ioctl to create an > iommu_domain where the IOMMU HW is directly travesering a > device-specific page table structure in user space memory. All the HW > today implements this by using another iommu_domain to allow the IOMMU > HW DMA access to user memory - ie nesting or multi-stage or whatever. > > This would come along with some ioctls to invalidate the IOTLB. > > I'm imagining this step as a iommu_group->op->create_user_domain() > driver callback which will create a new kind of domain with > domain-unique ops. Ie map/unmap related should all be NULL as those > are impossible operations. > > From there the usual struct device (ie RID) attach/detatch stuff needs > to take care of routing DMAs to this iommu_domain. > > Step two would be to add the ability for an iommufd using driver to > request that a RID&PASID is connected to an iommu_domain. This > connection can be requested for any kind of iommu_domain, kernel owned > or user owned. > > I don't quite have an answer how exactly the SMMUv3 vs Intel > difference in PASID routing should be resolved. > > to get answers I'm hoping to start building some sketch RFCs for these > different things on iommufd, hopefully in January. I'm looking at user > page tables, PASID, dirty tracking and userspace IO fault handling as > the main features iommufd must tackle. > > The purpose of the sketches would be to validate that the HW features > we want to exposed can work will with the choices the base is making. > > Jason >
