Messages in this thread | | | Date | Thu, 17 Mar 2022 14:51:34 -0400 | Subject | Re: [PATCH v4 15/32] vfio: introduce KVM-owned IOMMU type | From | Matthew Rosato <> |
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On 3/15/22 1:25 PM, Jason Gunthorpe wrote: > On Tue, Mar 15, 2022 at 12:29:02PM -0400, Matthew Rosato wrote: >> On 3/15/22 10:38 AM, Jason Gunthorpe wrote: >>> On Tue, Mar 15, 2022 at 09:49:01AM -0400, Matthew Rosato wrote: >>> >>>> The rationale for splitting steps 1 and 2 are that VFIO_SET_IOMMU doesn't >>>> have a mechanism for specifying more than the type as an arg, no? Otherwise >>>> yes, you could specify a kvm fd at this point and it would have some other >>>> advantages (e.g. skip notifier). But we still can't use the IOMMU for >>>> mapping until step 3. >>> >>> Stuff like this is why I'd be much happier if this could join our >>> iommfd project so we can have clean modeling of the multiple iommu_domains. >>> >> >> I'd certainly be willing to collaborate so feel free to loop me in on the >> discussions; > > Sure, I have you on my list. I've been waiting for Eric to get a bit > further along on his ARM work so you have something appropriate to > look at. > > In the mean time you can certainly work out the driver details as > you've been doing here and hacking through VFIO. The iommu_domain > logic is the big work item in this series, not the integration with > the uAPI. >
A subset of this series (enabling some s390x firmware-assist facilities) is not tied to the iommu and would still provide value while continuing to use vfio_iommu_type1 for all mapping -- so I think I'll look into a next version that shrinks down to that subset (+ re-visit the setup API).
Separate from that, I will continue looking at implementing the nested iommu_domain logic for s390, and continue to hack through VFIO for now. I'll use an RFC series when I have something more to look at, likely starting with the fully-pinned guest as you suggest; ultimately I'm interested in both scenarios (pinned kvm guest & dynamic pinning during shadow)
Thanks, Matt
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