Hi, On 9/16/20 6:32 PM, Jason Gunthorpe wrote: > On Wed, Sep 16, 2020 at 06:20:52PM +0200, Jean-Philippe Brucker wrote: >> On Wed, Sep 16, 2020 at 11:51:48AM -0300, Jason Gunthorpe wrote: >>> On Wed, Sep 16, 2020 at 10:32:17AM +0200, Jean-Philippe Brucker wrote: >>>> And this is the only PASID model for Arm SMMU (and AMD IOMMU, I believe): >>>> the PASID space of a PCI function cannot be shared between host and guest, >>>> so we assign the whole PASID table along with the RID. Since we need the >>>> BIND, INVALIDATE, and report APIs introduced here to support nested >>>> translation, a /dev/sva interface would need to support this mode as well. >>> >>> Well, that means this HW cannot support PASID capable 'SIOV' style >>> devices in guests. >> >> It does not yet support Intel SIOV, no. It does support the standards, >> though: PCI SR-IOV to partition a device and PASIDs in a guest. > > SIOV is basically standards based, it is better thought of as a > cookbook on how to use PASID and IOMMU together. > >>> I admit whole function PASID delegation might be something vfio-pci >>> should handle - but only if it really doesn't fit in some /dev/sva >>> after we cover the other PASID cases. >> >> Wouldn't that be the duplication you're trying to avoid? A second >> channel for bind, invalidate, capability and fault reporting >> mechanisms? > > Yes, which is why it seems like it would be nicer to avoid it. Why I > said "might" :) > >> If we extract SVA parts of vfio_iommu_type1 into a separate chardev, >> PASID table pass-through [1] will have to use that. > > Yes, '/dev/sva' (which is a terrible name) would want to be the uAPI > entry point for controlling the vIOMMU related to PASID. > > Does anything in the [1] series have tight coupling to VFIO other than > needing to know a bus/device/function? It looks like it is mostly > exposing iommu_* functions as uAPI? this series does not use any PASID so it fits quite nicely into the VFIO framework I think. Besides cache invalidation that takes the struct device, other operations (MSI binding and PASID table passing operate on the iommu domain). Also we use the VFIO memory region and interrupt/eventfd registration mechanism to return faults. Thanks Eric > > Jason >
