On 6/16/25 09:20, Jason Gunthorpe wrote: > On Sun, Jun 15, 2025 at 02:47:15PM -0400, Demi Marie Obenour wrote: > >> Is a paravirtualized IOMMU with interrupt remapping something that makes >> sense? > > IMHO linking interrupt remapping to the iommu is a poor design, > interrupt routing belongs in the irq subsystem, not in the iommu.
I agree. > The fact AMD and Intel both coupled their interrupt routing to their > iommu hardware is just a weird design decision. ARM didn't do this, > for instance. Arm did the right thing here, IMO. > So I would not try to do this at all, you should have a > para-virtualized IRQ interface, not an extension to virtio-iommu > adding interrupt handling. :\ I don't disagree at all. > AFAIK hyperv shows how to build something like this. Would this need KVM patches? I'm concerned that implementing this in userspace would interact badly with the irqfd fast path. -- Sincerely, Demi Marie Obenour (she/her/hers)
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