Re: [RFC PATCH 3/3] hw/net/tulip: Set descriptor error bit when lenght is incorrect

[Jason Wang <jasowang@redhat.com>]

On 2020/4/24 上午7:16, Philippe Mathieu-Daudé wrote:
> When a frame lenght is incorrect, set the RDES0 'Error Summary'
> and 'Frame too long' bits. Then stop the receive process and
> trigger an abnormal interrupt. See [4.3.5 Receive Process].
>
> Cc: Li Qiang <liq3ea@gmail.com>
> Cc: Li Qiang <pangpei.lq@antfin.com>
> Cc: Ziming Zhang <ezrakiez@gmail.com>
> Cc: Jason Wang <jasowang@redhat.com>
> Cc: Prasad J Pandit <pjp@fedoraproject.org>
> Fixes: 8ffb7265af ("check frame size and r/w data length")
> Buglink: https://bugs.launchpad.net/bugs/1874539
> Reported-by: Helge Deller <deller@gmx.de>
> Signed-off-by: Philippe Mathieu-Daudé <f4bug@amsat.org>


Hi Philippe:

It's still unclear to me that how this fixes the stuck. Did you mean 
guest trigger the error condition and then recvoer by abnormal interrupt?

If yes, this sounds still like a bug somewhere in the code.

Thanks


> ---
>   hw/net/tulip.c | 16 ++++++++++++----
>   1 file changed, 12 insertions(+), 4 deletions(-)
>
> diff --git a/hw/net/tulip.c b/hw/net/tulip.c
> index 470f635acb..671f79b6f4 100644
> --- a/hw/net/tulip.c
> +++ b/hw/net/tulip.c
> @@ -158,7 +158,7 @@ static void tulip_next_rx_descriptor(TULIPState *s,
>       s->current_rx_desc &= ~3ULL;
>   }
>   
> -static void tulip_copy_rx_bytes(TULIPState *s, struct tulip_descriptor *desc)
> +static int tulip_copy_rx_bytes(TULIPState *s, struct tulip_descriptor *desc)
>   {
>       int len1 = (desc->control >> RDES1_BUF1_SIZE_SHIFT) & RDES1_BUF1_SIZE_MASK;
>       int len2 = (desc->control >> RDES1_BUF2_SIZE_SHIFT) & RDES1_BUF2_SIZE_MASK;
> @@ -177,7 +177,8 @@ static void tulip_copy_rx_bytes(TULIPState *s, struct tulip_descriptor *desc)
>                             "(ofs: %u, len:%d, size:%zu)\n",
>                             __func__, s->rx_frame_len, len,
>                             sizeof(s->rx_frame));
> -            return;
> +            s->rx_frame_len = 0;
> +            return -1;
>           }
>           pci_dma_write(&s->dev, desc->buf_addr1, s->rx_frame +
>               (s->rx_frame_size - s->rx_frame_len), len);
> @@ -197,12 +198,15 @@ static void tulip_copy_rx_bytes(TULIPState *s, struct tulip_descriptor *desc)
>                             "(ofs: %u, len:%d, size:%zu)\n",
>                             __func__, s->rx_frame_len, len,
>                             sizeof(s->rx_frame));
> -            return;
> +            s->rx_frame_len = 0;
> +            return -1;
>           }
>           pci_dma_write(&s->dev, desc->buf_addr2, s->rx_frame +
>               (s->rx_frame_size - s->rx_frame_len), len);
>           s->rx_frame_len -= len;
>       }
> +
> +    return 0;
>   }
>   
>   static bool tulip_filter_address(TULIPState *s, const uint8_t *addr)
> @@ -274,7 +278,11 @@ static ssize_t tulip_receive(TULIPState *s, const uint8_t *buf, size_t size)
>               s->rx_frame_len = s->rx_frame_size;
>           }
>   
> -        tulip_copy_rx_bytes(s, &desc);
> +        if (tulip_copy_rx_bytes(s, &desc)) {
> +            desc.status |= RDES0_ES | RDES0_TL; /* Error: frame too long */
> +            s->csr[5] |= CSR5_RPS; /* Receive process stopped */
> +            tulip_update_int(s);
> +        }
>   
>           if (!s->rx_frame_len) {
>               desc.status |= s->rx_status;