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 <CACGkMEu8JtT9_0YcbmfWCGxbrB1GHnesnspFYgaeVrb2x3o3oQ@mail.gmail.com> <1677578798.8465447-1-xuanzhuo@linux.alibaba.com>
In-Reply-To: <1677578798.8465447-1-xuanzhuo@linux.alibaba.com>
From:   Rob Bradford <rbradford@rivosinc.com>
Date:   Wed, 1 Mar 2023 14:25:05 +0000
Message-ID: <CABPZdxussbbsqtrKZ8bbxSJYU4xuJphTJtvxV=jHHHWs7cO6+A@mail.gmail.com>
Subject: Re: [PATCH v2] virtio-net: Fix probe of virtio-net on kvmtool
To:     Xuan Zhuo <xuanzhuo@linux.alibaba.com>
Cc:     Jason Wang <jasowang@redhat.com>,
        "Michael S. Tsirkin" <mst@redhat.com>, netdev@vger.kernel.org,
        linux-kernel@vger.kernel.org,
        virtualization@lists.linux-foundation.org,
        Eric Dumazet <edumazet@google.com>,
        Jakub Kicinski <kuba@kernel.org>,
        Paolo Abeni <pabeni@redhat.com>,
        "David S. Miller" <davem@davemloft.net>
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On Tue, 28 Feb 2023 at 10:08, Xuan Zhuo <xuanzhuo@linux.alibaba.com> wrote:
>
> On Fri, 24 Feb 2023 11:11:37 +0800, Jason Wang <jasowang@redhat.com> wrote:
> > On Fri, Feb 24, 2023 at 3:38 AM Rob Bradford via B4 Relay
> > <devnull+rbradford.rivosinc.com@kernel.org> wrote:
> > >
> > > From: Rob Bradford <rbradford@rivosinc.com>
> > >
> > > kvmtool does not support the VIRTIO_NET_F_CTRL_GUEST_OFFLOADS feature
> > > but does advertise the VIRTIO_NET_F_GUEST_TSO{4,6} features. Check that
> > > the VIRTIO_NET_F_CTRL_GUEST_OFFLOADS feature is present before setting
> > > the NETIF_F_GRO_HW feature bit as otherwise
>
> Here are settings for dev->features and dev->hw_features.
>
>
> > > an attempt will be made to
> > > program the virtio-net device using the ctrl queue which will fail.
> > >
> > > This resolves the following error when running on kvmtool:
>
> Can you talk about it in detail what it did?

In the updated v3 version of the patch I went into a lot more detail,
particularly of why the bit was being cleared and triggering the
control queue reprogramming. Based on that I also adjusted the
conditional check.

Cheers,

Rob