Re: [PATCH v1] event/dlb2: add support for disabling PASID

[Thomas Monjalon <thomas@monjalon.net>]

08/06/2023 07:38, Jerin Jacob:
> On Thu, Jun 8, 2023 at 2:31 AM Abdullah Sevincer
> <abdullah.sevincer@intel.com> wrote:
> >
> > vfio-pci driver in Linux kernel 6.2 enables PASID by default.
> > In DLB hardware, enabling PASID puts DLB in SIOV mode. This
> > breaks DLB PF-PMD mode. For DLB PF-PMD mode to function properly
> > PASID needs to be disabled for kernel 6.2.
> >
> > In this commit this issue is addressed and PASID is disabled
> > by writing a zero to PASID control register.
> >
> > Signed-off-by: Abdullah Sevincer <abdullah.sevincer@intel.com>
> 
> > +       /* The current Linux kernel vfio driver does not expose PASID capability to
> > +        * users. It also enables PASID by default, which breaks DLB PF PMD. We have
> > +        * to use the hardcoded offset for now to disable PASID.
> > +        */
> > +       pasid_cap_offset = DLB2_PCI_PASID_CAP_OFFSET;
> > +
> > +       off = pasid_cap_offset + DLB2_PCI_PASID_CTRL;
> 
> +++ additional folks.
> 
> Is make sense to move this helper function to PCI common for disabling
> PASID for a PCI device so that other driver can use if needed
> as the implementation is not specific to DLB2.

I guess yes it makes sense.