Re: [PATCH v8 1/4] PCI/ATS: Ensure pci_ats_supported() is PF-aware for VFs

[Bjorn Helgaas]

On Thu, Jun 04, 2026 at 06:21:13PM +0000, Pranjal Shrivastava wrote:
> Update pci_ats_supported() to additionally check the associated PF's
> status when called on a VF. This ensures that PF-level quirks and
> untrusted status are correctly propagated to VFs, providing a robust
> support check that aligns with the kernel's PF-centric ATS configuration
> model and is immune to the timing of VF-specific fixups.
> 
> Reviewed-by: Jason Gunthorpe <jgg@xxxxxxxxxx>
> Reviewed-by: Samiullah Khawaja <skhawaja@xxxxxxxxxx>
> Reviewed-by: Nicolin Chen <nicolinc@xxxxxxxxxx>
> Reviewed-by: Lu Baolu <baolu.lu@xxxxxxxxxxxxxxx>
> Reviewed-by: Kevin Tian <kevin.tian@xxxxxxxxx>
> Signed-off-by: Pranjal Shrivastava <praan@xxxxxxxxxx>

Acked-by: Bjorn Helgaas <bhelgaas@xxxxxxxxxx>

This series looks like material for the IOMMU tree?  Let me know if
you prefer merging these via PCI.

> ---
>  drivers/pci/ats.c | 7 +++++--
>  1 file changed, 5 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/pci/ats.c b/drivers/pci/ats.c
> index 96efa00d9743..679a3c3c1d54 100644
> --- a/drivers/pci/ats.c
> +++ b/drivers/pci/ats.c
> @@ -40,10 +40,13 @@ void pci_ats_init(struct pci_dev *dev)
>   */
>  bool pci_ats_supported(struct pci_dev *dev)
>  {
> -	if (!dev->ats_cap)
> +	if (!dev->ats_cap || dev->untrusted)
>  		return false;
>  
> -	return (dev->untrusted == 0);
> +	if (dev->is_virtfn)
> +		return pci_ats_supported(pci_physfn(dev));
> +
> +	return true;
>  }
>  EXPORT_SYMBOL_GPL(pci_ats_supported);
>  
> -- 
> 2.54.0.1032.g2f8565e1d1-goog
>