Re: [RFC PATCH v2 1/7] vfio-ccw: Return IOINST_CC_NOT_OPERATIONAL for EIO

[Cornelia Huck]

On Thu,  6 Feb 2020 22:45:03 +0100
Eric Farman <address@hidden> wrote:

> From: Farhan Ali <address@hidden>
> 
> EIO is returned by vfio-ccw mediated device when the backing
> host subchannel is not operational anymore. So return cc=3
> back to the guest, rather than returning a unit check.
> This way the guest can take appropriate action such as
> issue an 'stsch'.
> 
> Signed-off-by: Farhan Ali <address@hidden>
> Signed-off-by: Eric Farman <address@hidden>
> ---
> 
> Notes:
>     v1->v2: [EF]
>      - Add s-o-b
>      - [Seems the discussion on v1 centered on the return code
>        set in the kernel, rather than anything that needs to
>        change here, unless I've missed something.]

I've stared at this and at the kernel code for some time again; and I'm
not sure if "return -EIO == not operational" is even true. That said,
I'm not sure a unit check is the right response, either. The only thing
I'm sure about is that the kernel code needs some review of return
codes and some documentation...

> 
>  hw/vfio/ccw.c | 1 +
>  1 file changed, 1 insertion(+)
> 
> diff --git a/hw/vfio/ccw.c b/hw/vfio/ccw.c
> index 50cc2ec75c..19144ecfc7 100644
> --- a/hw/vfio/ccw.c
> +++ b/hw/vfio/ccw.c
> @@ -114,6 +114,7 @@ again:
>          return IOINST_CC_BUSY;
>      case -ENODEV:
>      case -EACCES:
> +    case -EIO:
>          return IOINST_CC_NOT_OPERATIONAL;
>      case -EFAULT:
>      default: