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

[Jerin Jacob <jerinjacobk@gmail.com>]

On Tue, Oct 31, 2023 at 4:12 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.
>
> Fixes: 5433956d5185 ("event/dlb2: add eventdev probe")
> Cc: stable@dpdk.org
>
> Signed-off-by: Abdullah Sevincer <abdullah.sevincer@intel.com>
> ---
>  drivers/event/dlb2/pf/dlb2_main.c | 27 +++++++++++++++++++++++++++
>  lib/pci/rte_pci.h                 |  5 +++++
>  2 files changed, 32 insertions(+)
>
> diff --git a/drivers/event/dlb2/pf/dlb2_main.c b/drivers/event/dlb2/pf/dlb2_main.c
> index aa03e4c311..34e47a4e33 100644
> --- a/drivers/event/dlb2/pf/dlb2_main.c
> +++ b/drivers/event/dlb2/pf/dlb2_main.c
> @@ -190,6 +190,7 @@ dlb2_pf_reset(struct dlb2_dev *dlb2_dev)
>         uint16_t rt_ctl_word;
>         uint32_t pri_reqs_dword;
>         uint16_t pri_ctrl_word;
> +       uint16_t pasid_ctrl;
>
>         off_t pcie_cap_offset;
>         int pri_cap_offset;
> @@ -197,6 +198,7 @@ dlb2_pf_reset(struct dlb2_dev *dlb2_dev)
>         int err_cap_offset;
>         int acs_cap_offset;
>         int wait_count;
> +       int pasid_cap_offset;
>
>         uint16_t devsta_busy_word;
>         uint16_t devctl_word;
> @@ -514,6 +516,31 @@ dlb2_pf_reset(struct dlb2_dev *dlb2_dev)
>                 }
>         }
>
> +       /* TODO - The current Linux kernel 6.2 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. It may be different for
> +        * other device drivers since they may have different design. When PASID capability
> +        * is exposed to users, please revise this part and add api to disable PASID through
> +        * pci common code.
> +        */
> +       pasid_cap_offset = RTE_PCI_PASID_CAP_OFFSET;
> +
> +       off = pasid_cap_offset + RTE_PCI_PASID_CTRL;
> +       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;
>  }

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.