Re: [PATCH v3] event/dlb2: fix disable PASID for kernel 6.2

[Jerin Jacob <jerinjacobk@gmail.com>]

On Tue, Oct 31, 2023 at 8:43 PM Sevincer, Abdullah
<abdullah.sevincer@intel.com> wrote:
>
>
> > +This patch can be splited as two,
> > +1) Generic PCIe function to enable/disable PASID
> > +2) Call generic function to disable PASID in drivers/event/dlb2/. Also mention which Linux kernel commit is introducing this issue in the git commit log.
>
> Hi Jerrin,
> I think I need to provide more information here, then we can decide which way we will go would be good for now. I agree to having 2 functions in pci common
> code to enable/disable PASID, but we need to have hardcoded PASID cap offset inside these functions as well since PASID capability is not exposed to user. Hence, to be more specific
> main reason to have hardcoded PASID is, rte_pci_find_ext_capability() function to retrieve the offset returns '0' since PASID is not exposed to user yet.
>
> We can see this is vfio_pci_config.c in kernel code where PASID is not exposed to user.
> [PCI_EXT_CAP_ID_PASID]  =       0,      /* not yet */
>
> So if it is okay to go with hardcoded offset now in these functions I will move the implementation to pci_common file.

I would suggest, add argument option to API whether to probe the
capability or not? - 0 means probe and- non zero means specific PASID
cap offset till Linux VFIO is exposing it.