Re: [PATCH 1/2] iommu/vt-d: Skip dev-iotlb flush for inaccessible PCIe device without scalable mode

[Baolu Lu]

On 12/11/25 12:17, Jinhui Guo wrote:
> On Thu, Dec 11, 2025 10:10:52AM +0800, Baolu Lu wrote:
> > > Since __context_flush_dev_iotlb() is only called on
> > > {attach,release}_dev paths (not hot), add pci_device_is_present()
> > > there to skip inaccessible devices and avoid the hard-lock.
> > >
> > > Fixes: 37764b952e1b ("iommu/vt-d: Global devTLB flush when present context entry changed")
> > > Fixes: 81e921fd3216 ("iommu/vt-d: Fix NULL domain on device release")
> > Cc:stable@xxxxxxxxxxxxxxx
> >
> > > Signed-off-by: Jinhui Guo<guojinhui.liam@xxxxxxxxxxxxx>
> > > ---
> > >    drivers/iommu/intel/pasid.c | 11 +++++++++++
> > >    1 file changed, 11 insertions(+)
> > >
> > > diff --git a/drivers/iommu/intel/pasid.c b/drivers/iommu/intel/pasid.c
> > > index 3e2255057079..b1e8eb6a6504 100644
> > > --- a/drivers/iommu/intel/pasid.c
> > > +++ b/drivers/iommu/intel/pasid.c
> > > @@ -1099,9 +1099,20 @@ int intel_pasid_setup_sm_context(struct device *dev)
> > >     */
> > >    static void __context_flush_dev_iotlb(struct device_domain_info *info)
> > >    {
> > > +	struct pci_dev *pdev;
> > > +
> > >    	if (!info->ats_enabled)
> > >    		return;
> > >    
> > > +	/*
> > > +	 * Skip dev-IOTLB flush for inaccessible PCIe devices to prevent the
> > > +	 * Intel IOMMU from waiting indefinitely for an ATS invalidation that
> > > +	 * cannot complete.
> > > +	 */
> > > +	pdev = dev_is_pci(info->dev) ? to_pci_dev(info->dev) : NULL;
> > > +	if (pdev && !pci_device_is_present(pdev))
> > > +		return;
> > Could simply be
> >
> > 	if (dev_is_pci(info->dev) &&
> > 	    !pci_device_is_present(to_pci_dev(info->dev)))
> > 		return;
> >
> > ?
> >
> > > +
> > >    	qi_flush_dev_iotlb(info->iommu, PCI_DEVID(info->bus, info->devfn),
> > >    			   info->pfsid, info->ats_qdep, 0, MAX_AGAW_PFN_WIDTH);
> > >    
> > Thanks,
> > baolu
> Hi, baolu
>
> Thanks for your time and suggestions.
>
> I’ve sent v2 (https://lore.kernel.org/all/20251211035946.2071-1- 
> guojinhui.liam@xxxxxxxxxxxxx/)
> with the following changes:
>
> 1. Simplified the pci_device_is_present() check in __context_flush_dev_iotlb().
> 2. Added Cc:stable@xxxxxxxxxxxxxxx to both patches.

Thanks! I would suggest not updating the patch versions so frequently
next time. It is important to provide the reviewers with more time to
comment on your submissions. :-)

Thanks,
baolu