Re: [PATCH RFCv2 09/13] iommufd: Add IOMMU_OPTION_SW_MSI_START/SIZE ioctls

[Jason Gunthorpe]

On Fri, Feb 07, 2025 at 10:30:20AM -0400, Jason Gunthorpe wrote:
> On Thu, Feb 06, 2025 at 08:26:05PM -0800, Nicolin Chen wrote:
> > Yea, I found iopt_reserve_iova() is actually missed entirely...
> > 
> > While fixing this, I see a way to turn the OPTIONs back to per-
> > idev, if you still prefer them to be per-idev(?). Then, we can
> > check a given input in the set_option() against the device's
> > reserved region list from the driver, prior to device attaching
> > to any HWPT.
> 
> I didn't have a strong opinion, if the idev works without complexity
> then I'd stick with that on the basis of narrower scope is usually
> better.

If you make it per-idev then it is also implicitly per-GIC as well
since each idev has exactly one GIC

This would make it useful as a way to get each ITS page mapped into a
single fixed location.. 

Really hard to use from the VMM though

Jason