Re: [PATCH v3 5/6] vdpa: Add vhost_vdpa_net_load_offloads()

[Hawkins Jiawei]

On 2023/6/1 22:12, Eugenio Perez Martin wrote:
> On Thu, Jun 1, 2023 at 3:49 PM Hawkins Jiawei <yin31149@gmail.com> wrote:
>>
>> This patch introduces vhost_vdpa_net_load_offloads() to
>> restore offloads state at device's startup.
>>
>> Signed-off-by: Hawkins Jiawei <yin31149@gmail.com>
>> ---
>>   net/vhost-vdpa.c | 38 ++++++++++++++++++++++++++++++++++++++
>>   1 file changed, 38 insertions(+)
>>
>> diff --git a/net/vhost-vdpa.c b/net/vhost-vdpa.c
>> index e907a3c792..0e647886d1 100644
>> --- a/net/vhost-vdpa.c
>> +++ b/net/vhost-vdpa.c
>> @@ -678,6 +678,40 @@ static int vhost_vdpa_net_load_mq(VhostVDPAState *s,
>>       return *s->status != VIRTIO_NET_OK;
>>   }
>>
>> +static int vhost_vdpa_net_load_offloads(VhostVDPAState *s,
>> +                                        const VirtIONet *n)
>> +{
>> +    uint64_t offloads;
>> +    ssize_t dev_written;
>> +
>> +    if (!virtio_vdev_has_feature(&n->parent_obj,
>> +                                 VIRTIO_NET_F_CTRL_GUEST_OFFLOADS)) {
>> +        return 0;
>> +    }
>> +
>> +    offloads = cpu_to_le64(n->curr_guest_offloads);
>
> n->curr_guest_offloads is already stored in CPU order, we should only
> byte-swap it by the time of sending.

Yes, you are right.

I will correct it in the v4 patch.

Thanks!


>
> Thanks!
>
>> +
>> +    if (offloads == virtio_net_supported_guest_offloads(n)) {
>> +        /*
>> +         * According to VirtIO standard, "Upon feature negotiation
>> +         * corresponding offload gets enabled to preserve
>> +         * backward compatibility."
>> +         * So we do not need to send this CVQ command if the guest
>> +         * also enables all supported offloads.
>> +         */
>> +        return 0;
>> +    }
>> +
>> +    dev_written = vhost_vdpa_net_load_cmd(s, VIRTIO_NET_CTRL_GUEST_OFFLOADS,
>> +                                          
>> VIRTIO_NET_CTRL_GUEST_OFFLOADS_SET,
>> +                                          &offloads, sizeof(offloads));
>> +    if (unlikely(dev_written < 0)) {
>> +        return dev_written;
>> +    }
>> +
>> +    return *s->status != VIRTIO_NET_OK;
>> +}
>> +
>>   static int vhost_vdpa_net_load(NetClientState *nc)
>>   {
>>       VhostVDPAState *s = DO_UPCAST(VhostVDPAState, nc, nc);
>> @@ -700,6 +734,10 @@ static int vhost_vdpa_net_load(NetClientState *nc)
>>       if (unlikely(r)) {
>>           return r;
>>       }
>> +    r = vhost_vdpa_net_load_offloads(s, n);
>> +    if (unlikely(r)) {
>> +        return r;
>> +    }
>>
>>       return 0;
>>   }
>> --
>> 2.25.1
>>
>