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

[Jerin Jacob <jerinjacobk@gmail.com>]

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.



> +       if (rte_pci_read_config(pdev, &pasid_ctrl, 2, off) != 2)
> +               pasid_ctrl = 0;
> +
> +       if (pasid_ctrl) {
> +               DLB2_INFO(dlb2_dev, "DLB2 disabling pasid...\n");
> +
> +               pasid_ctrl = 0;
> +               ret = rte_pci_write_config(pdev, &pasid_ctrl, 2, off);
> +               if (ret != 2) {
> +                       DLB2_LOG_ERR("[%s()] failed to write the pcie config space at offset %d\n",
> +                               __func__, (int)off);
> +                       return ret;
> +               }
> +       }
> +
>         return 0;
>  }
>
> --
> 2.25.1
>