Re: [PATCH rc v6] iommu: Fix nested pci_dev_reset_iommu_prepare/done()

[Nicolin Chen <nicolinc@nvidia.com>]

On Tue, Apr 21, 2026 at 07:01:22AM +0000, Tian, Kevin wrote:
> > From: Nicolin Chen <nicolinc@nvidia.com>
> > Sent: Saturday, April 18, 2026 12:57 PM
> > 
> > On Fri, Apr 17, 2026 at 02:44:41PM -0700, Nicolin Chen wrote:
> > > @@ -2469,9 +2469,2 @@ static int
> > __iommu_group_set_domain_internal(struct iommu_group *group,
> > >
> > > -       /*
> > > -        * This is a concurrent attach during device recovery. Reject it until
> > > -        * pci_dev_reset_iommu_done() attaches the device to group->domain.
> > > -        */
> > > -       if (group->recovery_cnt)
> > > -               return -EBUSY;
> > > -
> > 
> > On a second thought, we may not simply drop this -- IIRC, we added
> > it particularly to fence a case where gdevs share the same RID or
> > some corner case like that?
> > 
> 
> this is by design according to the original commit:
> 
> "
>     Note that there are two corner cases:
>      1. Devices in the same iommu_group
>         Since an attachment is always per iommu_group, this means that any
>         sibling devices in the iommu_group cannot change domain, to prevent
>         race conditions.
>     ...
> "

Well, we changed the implementation a few times, and it isn't in
the merged v8 cover-letter..

Nicolin