From 2c7482486c5e079d3f43cb0cc6954fe6f1f33c22 Mon Sep 17 00:00:00 2001 From: "Dr. David Alan Gilbert" Date: Mon, 15 Aug 2016 10:40:17 +0200 Subject: [PATCH 16/17] virtio: set low features early on load RH-Author: Dr. David Alan Gilbert Message-id: <1471257618-19311-2-git-send-email-dgilbert@redhat.com> Patchwork-id: 71957 O-Subject: [RHEL-7.3 qemu-kvm-rhev PATCH 1/2] virtio: set low features early on load Bugzilla: 1365747 RH-Acked-by: Marcel Apfelbaum RH-Acked-by: Xiao Wang RH-Acked-by: Michael S. Tsirkin From: "Michael S. Tsirkin" virtio migrates the low 32 feature bits twice, the first copy is there for compatibility but ever since 019a3edbb25f1571e876f8af1ce4c55412939e5d: ("virtio: make features 64bit wide") it's ignored on load. This is wrong since virtio_net_load tests self announcement and guest offloads before the second copy including high feature bits is loaded. This means that self announcement, control vq and guest offloads are all broken after migration. Fix it up by loading low feature bits: somewhat ugly since high and low bits become out of sync temporarily, but seems unavoidable for compatibility. The right thing to do for new features is probably to test the host features, anyway. Fixes: 019a3edbb25f1571e876f8af1ce4c55412939e5d ("virtio: make features 64bit wide") Cc: qemu-stable@nongnu.org Reported-by: Robin Geuze Tested-by: Robin Geuze Signed-off-by: Michael S. Tsirkin (cherry picked from commit 62cee1a28aada2cce4b0e1fb835d8fc830aed7ac) Signed-off-by: Miroslav Rezanina --- hw/virtio/virtio.c | 10 ++++++++++ 1 file changed, 10 insertions(+) diff --git a/hw/virtio/virtio.c b/hw/virtio/virtio.c index d5933d1..300ce30 100644 --- a/hw/virtio/virtio.c +++ b/hw/virtio/virtio.c @@ -1511,6 +1511,16 @@ int virtio_load(VirtIODevice *vdev, QEMUFile *f, int version_id) } qemu_get_be32s(f, &features); + /* + * Temporarily set guest_features low bits - needed by + * virtio net load code testing for VIRTIO_NET_F_CTRL_GUEST_OFFLOADS + * VIRTIO_NET_F_GUEST_ANNOUNCE and VIRTIO_NET_F_CTRL_VQ. + * + * Note: devices should always test host features in future - don't create + * new dependencies like this. + */ + vdev->guest_features = features; + config_len = qemu_get_be32(f); /* -- 1.8.3.1