[Skiboot] [PATCH skiboot] npu2: Reset NVLinks on hot reset

[Balbir Singh]

On Wed, Jun 13, 2018 at 4:22 PM, Alexey Kardashevskiy <aik at ozlabs.ru> wrote:
> This effectively fences GPU RAM on GPU reset so the host system
> does not have to crash every time we stop a KVM guest with a GPU
> passed through.
>
> Suggested-by: Balbir Singh <bsingharora at gmail.com>
> Signed-off-by: Alexey Kardashevskiy <aik at ozlabs.ru>
> ---
>  hw/npu2.c | 14 ++++++++++++++
>  1 file changed, 14 insertions(+)
>
> diff --git a/hw/npu2.c b/hw/npu2.c
> index 238fff4..3ed089f 100644
> --- a/hw/npu2.c
> +++ b/hw/npu2.c
> @@ -1092,6 +1092,20 @@ static int64_t npu2_get_power_state(struct pci_slot *slot __unused, uint8_t *val
>
>  static int64_t npu2_hreset(struct pci_slot *slot __unused)
>  {
> +       struct npu2 *p;
> +       int i;
> +       struct npu2_dev *ndev;
> +
> +       p = phb_to_npu2_nvlink(slot->phb);
> +       NPU2INF(p, "Hreset PHB state\n");
> +
> +       for (i = 0; i < p->total_devices; i++) {
> +               ndev = &p->devices[i];
> +               if (ndev) {
> +                       NPU2DEVINF(ndev, "Resetting device\n");
> +                       reset_ntl(ndev);
> +               }
> +       }
>         return OPAL_SUCCESS;
>  }

We may have some common code across hreset and sreset which can be fixedup later

Acked-by: Balbir Singh <bsingharora at gmail.com>