linux-kernel - Re: [PATCH net] virtio-net: reject small vring sizes

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Message-ID: <1681713856.1928573-2-xuanzhuo@linux.alibaba.com>
Date:   Mon, 17 Apr 2023 14:44:16 +0800
From:   Xuan Zhuo <xuanzhuo@...ux.alibaba.com>
To:     Alvaro Karsz <alvaro.karsz@...id-run.com>
Cc:     "davem@...emloft.net" <davem@...emloft.net>,
        "edumazet@...gle.com" <edumazet@...gle.com>,
        "kuba@...nel.org" <kuba@...nel.org>,
        "pabeni@...hat.com" <pabeni@...hat.com>,
        "virtualization@...ts.linux-foundation.org" 
        <virtualization@...ts.linux-foundation.org>,
        "netdev@...r.kernel.org" <netdev@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "Michael S. Tsirkin" <mst@...hat.com>,
        Jason Wang <jasowang@...hat.com>
Subject: Re: [PATCH net] virtio-net: reject small vring sizes

On Mon, 17 Apr 2023 06:38:43 +0000, Alvaro Karsz <alvaro.karsz@...id-run.com> wrote:
> > Actually, I think that all you need to do is disable NETIF_F_SG,
> > and things will work, no?
>
> I think that this is not so simple, if I understand correctly, by disabling NETIF_F_SG we will never receive a chained skbs to transmit, but we still have more functionality to address, for example:
> * The TX timeouts.

Why tx timeout without frags?

> * Guest GSO/big MTU (without VIRTIO_NET_F_MRG_RXBUF?), we can't chain page size buffers anymore.


Or, we disable the GUEST_GSO, HOST_GSO......

Thanks.

>
> > Alvaro, can you try?
>
> It won't matter at the moment, we'll get TX timeout after the first tx packet, we need to address this part as well.