Re: Virtio-IOMMU interrupt remapping design

[Jason Gunthorpe]

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.

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.

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. :\

AFAIK hyperv shows how to build something like this.

Jason