On Tue, Feb 08, 2022 at 03:33:58PM -0500, Matthew Rosato wrote: > > Is the purpose of IOAT to associate the device to a set of KVM page > > tables? That seems like a container or future iommufd operation. I > > Yes, here we are establishing a relationship with the DMA table in the guest > so that once mappings are established guest PCI operations (handled via > special instructions in s390) don't need to go through the host but can be > directly handled by firmware (so, effectively guest can keep running on its > vcpu vs breaking out). Oh, well, certainly sounds like a NAK on that - anything to do with the DMA translation of a PCI device must go through the iommu layer, not here. Lets not repeat the iommu subsytem bypass mess power made please. > It's more that non-KVM userspace doesn't care about what these ioctls are > doing... The enabling of 'interp, aif, ioat' is only pertinent when there > is a KVM userspace, specifically because the information being shared / > actions being performed as a result are only relevant to properly enabling > zPCI features when the zPCI device is being passed through to a VM > guest. Then why are they KVM ioctls? Jason
