On Tue, Oct 01, 2024 at 10:48:15AM -0300, Jason Gunthorpe wrote: > On Sun, Sep 29, 2024 at 03:19:42PM +0800, Yi Liu wrote: > > > So their viommu HW concepts come along with a requirement that there > > > be a fixed translation for the VM, which we model by attaching a S2 > > > HWPT to the VIOMMU object which get's linked into the IOMMU HW as > > > the translation for the queue memory. > > > > Is the mapping of the S2 be static? or it an be unmapped per userspace? > > In principle it should be dynamic, but I think the vCMDQ stuff will > struggle to do that Yea. vCMDQ HW requires a setting of the physical address of the base address to a queue in the VM's ram space. If the S2 mapping changes (resulting a different queue location in the physical memory), VMM should notify the kernel for a HW reconfiguration. I wonder what all the user cases are, which can cause a shifting of S2 mappings? VM migration? Any others? Thanks Nicolin
