On Mon, Jun 16, 2025 at 10:20:31AM -0300, 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.
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.
why does it matter in which device it resides? Way I see it, there is little reason to remap interrupts without also using an iommu, so why not a single device. what did I miss?
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