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

[Helge Deller]

On 24.04.20 04:16, Jason Wang wrote:
> 
> 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 <address@hidden>
>> Cc: Li Qiang <address@hidden>
>> Cc: Ziming Zhang <address@hidden>
>> Cc: Jason Wang <address@hidden>
>> Cc: Prasad J Pandit <address@hidden>
>> Fixes: 8ffb7265af ("check frame size and r/w data length")
>> Buglink: https://bugs.launchpad.net/bugs/1874539
>> Reported-by: Helge Deller <address@hidden>
>> Signed-off-by: Philippe Mathieu-Daudé <address@hidden>
> 
> 
> 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.


Sadly the patches do not fix the bug.


Helge


> 
>> ---
>>   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;
>