Re: [PATCH v3 5/5] pci: Suspend iommu function prior to resetting a device

Nicolin Chen
2025-08-28T19:35:26Z

On Thu, Aug 28, 2025 at 03:46:08PM -0300, Jason Gunthorpe wrote:
> On Thu, Aug 28, 2025 at 08:08:13AM -0700, Nicolin Chen wrote:
> > On Thu, Aug 28, 2025 at 09:51:49AM -0300, Jason Gunthorpe wrote:
> > > On Fri, Aug 22, 2025 at 11:50:58AM -0700, Nicolin Chen wrote:
> > >
> > > > It feels like we need a no-fail re-attach operation, or at least an
> > > > unlikely-to-fail one. I recall years ago we tried a can_attach op
> > > > to test the compatibility but it didn't get merged. Maybe we'd need
> > > > it so that a concurrent attach can test compatibility, allowing the
> > > > re-attach in iommu_dev_reset_done() to more likely succeed.
> > >
> > > This is probably the cleanest option to split these things
> >
> > Yea, that could avoid failing a concurrent attach_dev during FLR
> > unless the dryrun fails, helping non-SRIOV cases too.
> >
> > So, next version could have some new preparatory patches:
> > - Pass in old domain to attach_dev
> > - Add a can_attach_dev op
>
> I wouldn't make this more complicated, just focus on the signal device
> case here then we move on from there
>
> Just adding can_attach_dev is big series on its own

OK. I suppose a concurrent attach on a single device will be rare,
so failing it won't impact that much and thus can be a Part-1.

Then, for part-2, we will do can_attach_dev and support SRIOV.

Thanks
Nicolin