Re: [RFC PATCH 0/5] iommu/arm-smmu-v3: Implement Runtime/System Sleep ops

[Jason Gunthorpe <jgg@ziepe.ca>]

On Wed, Mar 19, 2025 at 06:22:30PM +0000, Robin Murphy wrote:
> I don't see SVA and VFIO needing any special considerations, so it might
> just be the new vIOMMU stuff which may need to hold PM enabled for the
> lifetime of things exposed to userspace.

Are you expecting that the VFIO driver, and whatever driver is
managing the SVA will keep the power turned on as necessary then?

VFIO is not going to work if the SMMU power goes off unexpectedly
while the VFIO FD is open.

I suppose VFIO also can power off on-demand via userspace asking
it. In that case the VM would be co-operating.

vcmdq probably needs some suspend resume logic like the normal
commandq.

viommu I think will only uses STE fields so it should be OK?

SVA.. Is similar to VFIO, if the power goes off while the SVA is
working that is bad. The SVA requesting driver would have to manage
this. HW with userspace command submission probably can't allow the
power to go off while command submission is possible.

Jason