linux-kernel - Re: [REGRESSION][BISECTED] PCI Passthrough / SR-IOV Failure on Stable Kernel ≥ v6.12.35

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Message-ID: <2025072314-malformed-antler-2829@gregkh>
Date: Wed, 23 Jul 2025 11:39:33 +0200
From: Greg KH <gregkh@...uxfoundation.org>
To: Ban ZuoXiang <bbaa@...a.fun>
Cc: Baolu Lu <baolu.lu@...ux.intel.com>, iommu@...ts.linux.dev,
	linux-kernel@...r.kernel.org, stable@...r.kernel.org
Subject: Re: [REGRESSION][BISECTED] PCI Passthrough / SR-IOV Failure on Stable Kernel ≥
 v6.12.35

On Wed, Jul 23, 2025 at 05:22:44PM +0800, Ban ZuoXiang wrote:
> > Nope!  We need your help as you are the one that can reproduce it :)
> >
> > Are we missing a backport?  Did we get the backport incorrect?  Should
> > we just revert it?
> >
> > thanks,
> > greg k-h
> 
> Hi, greg k-h
> 
> Original patch:
> 
> > diff --git a/drivers/iommu/intel/iommu.c b/drivers/iommu/intel/iommu.c
> > index bb871674d8acba..226e174577fff1 100644
> > --- a/drivers/iommu/intel/iommu.c
> > +++ b/drivers/iommu/intel/iommu.c
> > @@ -4298,6 +4306,9 @@ static int identity_domain_attach_dev(struct
> > iommu_domain *domain, struct device
> >      else
> >          ret = device_setup_pass_through(dev);
> >  
> > +    if (!ret)
> > +        info->domain_attached = true;
> > +
> >      return ret;
> >  }
> Backport patch:
> > diff --git a/drivers/iommu/intel/iommu.c b/drivers/iommu/intel/iommu.c
> > index 157542c07aaafa..56e9f125cda9a0 100644
> > --- a/drivers/iommu/intel/iommu.c
> > +++ b/drivers/iommu/intel/iommu.c
> > @@ -4406,6 +4414,9 @@ static int device_set_dirty_tracking(struct
> > list_head *devices, bool enable)
> >              break;
> >      }
> >  
> > +    if (!ret)
> > +        info->domain_attached = true;
> > +
> >      return ret;
> >  }
> 
> The last hunk of the original patch [1] was applied to the
> |identity_domain_attach_dev| function, 
> but the last hunk of the backport patch [2] appears to have been
> mistakenly applied to the |device_set_dirty_tracking| function.
> I can confirm that correctly placing the patch from
> device_set_dirty_tracking into identity_domain_attach_dev resolves the
> issue.
> 
> [1]
> https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=320302baed05c6456164652541f23d2a96522c06
> [2]
> https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=fb5873b779dd5858123c19bbd6959566771e2e83

Ah, nice work!

Can you send a patch that fixes this up properly please?  I'll be glad
to queue that up.

greg k-h