From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:46116) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1Z7LMM-0005ou-NR for qemu-devel@nongnu.org; Tue, 23 Jun 2015 06:23:19 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1Z7LMI-00055v-O0 for qemu-devel@nongnu.org; Tue, 23 Jun 2015 06:23:18 -0400 Received: from mx1.redhat.com ([209.132.183.28]:50427) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1Z7LMI-00055g-It for qemu-devel@nongnu.org; Tue, 23 Jun 2015 06:23:14 -0400 Message-ID: <5589338E.80304@redhat.com> Date: Tue, 23 Jun 2015 13:23:10 +0300 From: Marcel Apfelbaum MIME-Version: 1.0 References: <1434650744-6585-1-git-send-email-marcel@redhat.com> <20150623115705-mutt-send-email-mst@redhat.com> In-Reply-To: <20150623115705-mutt-send-email-mst@redhat.com> Content-Type: text/plain; charset=windows-1252; format=flowed Content-Transfer-Encoding: 7bit Subject: Re: [Qemu-devel] [PATCH] net/virtio: fix multi-queue negotiation List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: "Michael S. Tsirkin" Cc: famz@redhat.com, qemu-devel@nongnu.org, n.nikolaev@virtualopensystems.com On 06/23/2015 12:57 PM, Michael S. Tsirkin wrote: > On Thu, Jun 18, 2015 at 09:05:44PM +0300, Marcel Apfelbaum wrote: >> Clear host multi-queue related features if the peer >> doesn't support it. >> >> Signed-off-by: Marcel Apfelbaum >> --- >> Notes: >> This fixes a guest CPU soft lock, however the virtio-net >> device will not work correctly. It seems that is >> peer's "fault", not knowing how to handle the situation. >> However, I submit this patch since it corrects the negotiation >> and saves us from a guest crash (!). >> >> Any ideas from the virtio/multi-queue developers on how to debug >> this further are welcomed. >> >> hw/net/virtio-net.c | 13 ++++++++++++- >> 1 file changed, 12 insertions(+), 1 deletion(-) >> >> diff --git a/hw/net/virtio-net.c b/hw/net/virtio-net.c >> index 9281aa1..63e59e8 100644 >> --- a/hw/net/virtio-net.c >> +++ b/hw/net/virtio-net.c >> @@ -367,6 +367,11 @@ static int peer_has_ufo(VirtIONet *n) >> return n->has_ufo; >> } >> >> +static int peer_has_multiqueue(VirtIONet *n) >> +{ >> + return n->multiqueue; >> +} >> + >> static void virtio_net_set_mrg_rx_bufs(VirtIONet *n, int mergeable_rx_bufs, >> int version_1) >> { >> @@ -469,6 +474,13 @@ static uint64_t virtio_net_get_features(VirtIODevice *vdev, uint64_t features) >> virtio_clear_feature(&features, VIRTIO_NET_F_HOST_UFO); >> } >> >> + if (!peer_has_multiqueue(n)) { >> + virtio_clear_feature(&features, VIRTIO_NET_F_MQ); >> + virtio_clear_feature(&features, VIRTIO_NET_F_GUEST_ANNOUNCE); >> + virtio_clear_feature(&features, VIRTIO_NET_F_CTRL_VQ); >> + virtio_clear_feature(&features, VIRTIO_NET_F_CTRL_RX); >> + } >> + >> if (!get_vhost_net(nc->peer)) { >> virtio_add_feature(&features, VIRTIO_F_VERSION_1); >> return features; > > _MQ makes sense but what about the rest? Why clear them? Guest's virtio driver doesn't like if MQ is off and any of the other flags remains ON. It has a specific check for each of them and fails the loading if not all are off. Thanks, Marcel > >> @@ -1314,7 +1326,6 @@ static void virtio_net_tx_bh(void *opaque) >> static void virtio_net_set_multiqueue(VirtIONet *n, int multiqueue) >> { >> n->multiqueue = multiqueue; >> - >> virtio_net_set_queues(n); >> } >> >> -- >> 2.1.0