68 lines
2.6 KiB
Diff
68 lines
2.6 KiB
Diff
From 7c85ae20bc8a6bb2e08794d01e6f65af7626a05d Mon Sep 17 00:00:00 2001
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From: =?UTF-8?q?Eugenio=20P=C3=A9rez?= <eperezma@redhat.com>
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Date: Tue, 24 Jan 2023 17:11:59 +0100
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Subject: [PATCH] virtio-net: clear guest_announce feature if no cvq backend
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MIME-Version: 1.0
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Content-Type: text/plain; charset=UTF-8
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Content-Transfer-Encoding: 8bit
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Since GUEST_ANNOUNCE is emulated the feature bit could be set without
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backend support. This happens in the vDPA case.
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However, backend vDPA parent may not have CVQ support. This causes an
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incoherent feature set, and the driver may refuse to start. This
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happens in virtio-net Linux driver.
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This may be solved differently in the future. Qemu is able to emulate a
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CVQ just for guest_announce purposes, helping guest to notify the new
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location with vDPA devices that does not support it. However, this is
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left as a TODO as it is way more complex to backport.
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Tested with vdpa_net_sim, toggling manually VIRTIO_NET_F_CTRL_VQ in the
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driver and migrating it with x-svq=on.
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Fixes: 980003debddd ("vdpa: do not handle VIRTIO_NET_F_GUEST_ANNOUNCE in vhost-vdpa")
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Reported-by: Dawar, Gautam <gautam.dawar@amd.com>
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Signed-off-by: Eugenio Pérez <eperezma@redhat.com>
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Message-Id: <20230124161159.2182117-1-eperezma@redhat.com>
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Reviewed-by: Michael S. Tsirkin <mst@redhat.com>
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Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
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Reviewed-by: David Edmondson <david.edmondson@oracle.com>
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Reviewed-by: Gautam Dawar <gautam.dawar@amd.com>
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Tested-by: Gautam Dawar <gautam.dawar@amd.com>
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Tested-by: Lei Yang <leiyang@redhat.com>
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Signed-off-by: fangyi <eric.fangyi@huawei.com>
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---
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hw/net/virtio-net.c | 15 +++++++++++++++
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1 file changed, 15 insertions(+)
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diff --git a/hw/net/virtio-net.c b/hw/net/virtio-net.c
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index bc26f5347a..ae37b3461b 100644
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--- a/hw/net/virtio-net.c
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+++ b/hw/net/virtio-net.c
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@@ -771,6 +771,21 @@ static uint64_t virtio_net_get_features(VirtIODevice *vdev, uint64_t features,
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features |= (1ULL << VIRTIO_NET_F_MTU);
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}
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+ /*
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+ * Since GUEST_ANNOUNCE is emulated the feature bit could be set without
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+ * enabled. This happens in the vDPA case.
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+ *
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+ * Make sure the feature set is not incoherent, as the driver could refuse
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+ * to start.
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+ *
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+ * TODO: QEMU is able to emulate a CVQ just for guest_announce purposes,
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+ * helping guest to notify the new location with vDPA devices that does not
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+ * support it.
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+ */
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+ if (!virtio_has_feature(vdev->backend_features, VIRTIO_NET_F_CTRL_VQ)) {
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+ virtio_clear_feature(&features, VIRTIO_NET_F_GUEST_ANNOUNCE);
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+ }
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+
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return features;
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}
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--
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2.27.0
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