Re: [PATCH v2 1/1] s390x: css: report errors from ccw_dstream_read/write

[Halil Pasic <pasic@linux.ibm.com>]

On Thu,  8 Apr 2021 18:32:09 +0200
Pierre Morel <pmorel@linux.ibm.com> wrote:

> ccw_dstream_read/write functions returned values are sometime
> not taking into account and reported back to the upper level
> of interpretation of CCW instructions.
> 
> It follows that accessing an invalid address does not trigger
> a subchannel status program check to the guest as it should.
> 
> Let's test the return values of ccw_dstream_write[_buf] and
> ccw_dstream_read[_buf] and report it to the caller.
> 
> Signed-off-by: Pierre Morel <pmorel@linux.ibm.com>

Acked-by: Halil Pasic <pasic@linux.ibm.com>

I did not look into the whole scsw.count stuff or into wether
your changes to 3270 (look form <mark></mark> in the diff part) affect
more than just ccw_dstream_*.

I would have preferred this patch split up based on the intended effect
and thus also subsystem (css, virtio-ccw, 3270), but I've alluded to
that before, and since we are in a hurry I can live with it as is.

Regards,
Halil

> ---
>  hw/char/terminal3270.c | 11 +++++--
>  hw/s390x/3270-ccw.c    |  5 +++-
>  hw/s390x/css.c         | 14 +++++----
>  hw/s390x/virtio-ccw.c  | 66 ++++++++++++++++++++++++++++++------------
>  4 files changed, 69 insertions(+), 27 deletions(-)
> 
> diff --git a/hw/char/terminal3270.c b/hw/char/terminal3270.c
> index a9a46c8ed3..82e85fac2e 100644
> --- a/hw/char/terminal3270.c
> +++ b/hw/char/terminal3270.c
> @@ -200,9 +200,13 @@ static int read_payload_3270(EmulatedCcw3270Device *dev)
>  {
>      Terminal3270 *t = TERMINAL_3270(dev);
>      int len;
> +    int ret;
>  
>      len = MIN(ccw_dstream_avail(get_cds(t)), t->in_len);
> -    ccw_dstream_write_buf(get_cds(t), t->inv, len);
> +    ret = ccw_dstream_write_buf(get_cds(t), t->inv, len);
> +    if (ret < 0) {
> +        return ret;
> +    }
>      t->in_len -= len;
>  
>      return len;
> @@ -260,7 +264,10 @@ static int write_payload_3270(EmulatedCcw3270Device *dev, uint8_t cmd)
>  
>      t->outv[out_len++] = cmd;
>      do {
> -        ccw_dstream_read_buf(get_cds(t), &t->outv[out_len], len);
> +        retval = ccw_dstream_read_buf(get_cds(t), &t->outv[out_len], len);
> +        if (retval < 0) {
> +            return retval;
> +        }
>          count = ccw_dstream_avail(get_cds(t));
>          out_len += len;
>  
> diff --git a/hw/s390x/3270-ccw.c b/hw/s390x/3270-ccw.c
> index 821319eee6..f3e7342b1e 100644
> --- a/hw/s390x/3270-ccw.c
> +++ b/hw/s390x/3270-ccw.c
> @@ -31,6 +31,9 @@ static int handle_payload_3270_read(EmulatedCcw3270Device *dev, CCW1 *ccw)
>      }
>  
>      len = ck->read_payload_3270(dev);

<mark>

> +    if (len < 0) {
> +        return len;
> +    }
>      ccw_dev->sch->curr_status.scsw.count = ccw->count - len;
>  

</mark>

Do we eventually update scsw.count?

>      return 0;
> @@ -50,7 +53,7 @@ static int handle_payload_3270_write(EmulatedCcw3270Device *dev, CCW1 *ccw)
>      len = ck->write_payload_3270(dev, ccw->cmd_code);
>  
>      if (len <= 0) {

<mark>
> -        return -EIO;
> +        return len ? len : -EIO;

</mark>

>      }
>  
>      ccw_dev->sch->curr_status.scsw.count = ccw->count - len;
> diff --git a/hw/s390x/css.c b/hw/s390x/css.c
> index fe47751df4..4149b8e5a7 100644