As section 2.2 of the Virtio spec states about features
negotiation:
"During device initialization, the driver reads this and tells
the device the subset that it accepts. The only way to
renegotiate is to reset the device."
This patch implements a check to prevent illegal features change
while the device is running.
One exception is the VHOST_F_LOG_ALL feature bit, which is enabled
when live-migration is initiated. But this feature is not negotiated
with the Virtio driver, but directly with the Vhost master.
Signed-off-by: Maxime Coquelin <maxime.coque...@redhat.com>
---
lib/librte_vhost/vhost_user.c | 17 ++++++++++++++++-
1 file changed, 16 insertions(+), 1 deletion(-)
diff --git a/lib/librte_vhost/vhost_user.c b/lib/librte_vhost/vhost_user.c
index f4c7ce462..2d86c0ca8 100644
--- a/lib/librte_vhost/vhost_user.c
+++ b/lib/librte_vhost/vhost_user.c
@@ -183,7 +183,22 @@ vhost_user_set_features(struct virtio_net *dev, uint64_t
features)
return -1;
}
- if ((dev->flags & VIRTIO_DEV_RUNNING) && dev->features != features) {
+ if (dev->features == features)
+ return 0;
+
+ if (dev->flags & VIRTIO_DEV_RUNNING) {
+ /*
+ * Error out if master tries to change features while device is
+ * in running state. The exception being VHOST_F_LOG_ALL, which
+ * is enabled when the live-migration starts.
+ */
+ if ((dev->features ^ features) & ~(1ULL << VHOST_F_LOG_ALL)) {
+ RTE_LOG(ERR, VHOST_CONFIG,
+ "(%d) features changed while device is
running.\n",
+ dev->vid);
+ return -1;
+ }
+
if (dev->notify_ops->features_changed)
dev->notify_ops->features_changed(dev->vid, features);
}
--
2.14.3
