Re: [PATCH v2 1/5] iommu/amd: Refactor device probe and capability initialization

[Pranjal Shrivastava]

On Sat, Aug 22, 2026 at 06:34:42PM +0530, Vasant Hegde wrote:
> Pranjal,
> 
> 
> On 8/14/2026 7:26 AM, Pranjal Shrivastava wrote:
> > Restructure the device probe path to improve readability and prepare for
> > cleaner error handling. Refactor check_device() into iommu_lookup_device
> > to explicitly validate and return the amd_iommu ptr & devid. Refactor
> > iommu_init_device() to return the allocated dev_data. Consolidate all
> > PCI cap inits (MSI domains, PASID, ATS) into a new helper:
> > iommu_init_device_caps().
> > 
> > Suggested-by: Vasant Hegde <vasant.hegde@xxxxxxx>
> > Signed-off-by: Pranjal Shrivastava <praan@xxxxxxxxxx>
> > ---
> >  drivers/iommu/amd/iommu.c | 114 +++++++++++++++++++-------------------
> >  1 file changed, 56 insertions(+), 58 deletions(-)
> > 
> > diff --git a/drivers/iommu/amd/iommu.c b/drivers/iommu/amd/iommu.c
> > index 4c31294fabc5..9b8ad131ba79 100644
> > --- a/drivers/iommu/amd/iommu.c
> > +++ b/drivers/iommu/amd/iommu.c
> > @@ -675,7 +675,8 @@ static void pdev_disable_caps(struct pci_dev *pdev)
> 
> 
> .../...
> 
> > -	amd_iommu_set_pci_msi_domain(dev, iommu);
> > +	iommu_init_device_caps(dev_data, dev, iommu);
> >  	iommu_dev = &iommu->iommu;
> >  
> > -	/*
> > -	 * If IOMMU and device supports PASID then it will contain max
> > -	 * supported PASIDs, else it will be zero.
> > -	 */
> > -	dev_data = dev_iommu_priv_get(dev);
> > -	if (amd_iommu_pasid_supported() && dev_is_pci(dev) &&
> > -	    pdev_pasid_supported(dev_data)) {
> > -		dev_data->max_pasids = min_t(u32, iommu->iommu.max_pasids,
> > -					     pci_max_pasids(to_pci_dev(dev)));
> > -	}
> > -
> 
> Can you add something like below comment so that we know why we are not calling
> iommu_ignore_device in error path.

Ack, I'll add a comment about this.

> 
> +        * When DMA translation is unavailable return error so the iommu core
> +        * won't attempt domain attach for this device. But interrupt-remap
> +        * is still supported. Hence do not ignore the device.
> 
> -Vasant
> 

Thanks,
Praan