Re: [PATCH RFC 1/1] vdpa: Return -EINVAL if device's ack is VIRTIO_NET_ERR

[Hawkins Jiawei <yin31149@gmail.com>]

On 2023/7/4 0:52, Michael S. Tsirkin wrote:
> On Wed, Jun 14, 2023 at 09:01:47PM +0800, Hawkins Jiawei wrote:
>> According to VirtIO standard, "The class, command and
>> command-specific-data are set by the driver,
>> and the device sets the ack byte.
>> There is little it can do except issue a diagnostic
>> if ack is not VIRTIO_NET_OK."
>>
>> Therefore, QEMU should stop sending the queued SVQ commands and
>> cancel the device startup if the device's ack is not VIRTIO_NET_OK.
>>
>> Yet the problem is that, vhost_vdpa_net_load_x() returns 1 based on
>> `*s->status != VIRTIO_NET_OK` when the device's ack is VIRTIO_NET_ERR.
>> As a result, net->nc->info->load() also returns 1, this makes
>> vhost_net_start_one() incorrectly assume the device state is
>> successfully loaded by vhost_vdpa_net_load() and return 0, instead of
>> goto `fail` label to cancel the device startup, as vhost_net_start_one()
>> only cancels the device startup when net->nc->info->load() returns a
>> negative value.
>>
>> This patch fixes this problem by returning -EINVAL when the device's
>> ack is not VIRTIO_NET_OK.
>>
>> Fixes: f73c0c43ac ("vdpa: extract vhost_vdpa_net_load_mac from vhost_vdpa_net_load")
>> Fixes: f64c7cda69 ("vdpa: Add vhost_vdpa_net_load_mq")
>> Signed-off-by: Hawkins Jiawei <yin31149@gmail.com>
>> ---
>>   net/vhost-vdpa.c | 10 +++++++---
>>   1 file changed, 7 insertions(+), 3 deletions(-)
>>
>> diff --git a/net/vhost-vdpa.c b/net/vhost-vdpa.c
>> index 37cdc84562..630c9bf71e 100644
>> --- a/net/vhost-vdpa.c
>> +++ b/net/vhost-vdpa.c
>> @@ -651,8 +651,9 @@ static int vhost_vdpa_net_load_mac(VhostVDPAState *s, const VirtIONet *n)
>>           if (unlikely(dev_written < 0)) {
>>               return dev_written;
>>           }
>> -
>> -        return *s->status != VIRTIO_NET_OK;
>> +        if (*s->status != VIRTIO_NET_OK) {
>> +            return -EINVAL;
>> +        }
>>       }
>>
>>       return 0;
>> @@ -676,8 +677,11 @@ static int vhost_vdpa_net_load_mq(VhostVDPAState *s,
>>       if (unlikely(dev_written < 0)) {
>>           return dev_written;
>>       }
>> +    if (*s->status != VIRTIO_NET_OK) {
>> +        return -EINVAL;
>> +    }
>>
>> -    return *s->status != VIRTIO_NET_OK;
>> +    return 0;
>>   }
>
> I think EIO would be better, we have too many EINVAL cases,
> making things hard to debug.

I will refactor this patch to return -EIO according to your suggestion.

Thanks!

>
>
>>

>>   static int vhost_vdpa_net_load(NetClientState *nc)
>> --
>> 2.25.1
>