From 8c2a9a75eca9cf89a085674180cf2b18e8eeba7b Mon Sep 17 00:00:00 2001
From: Cathy Zhang <cathy.zhang@intel.com>
Date: Tue, 3 Sep 2019 16:26:01 +0800
Subject: [PATCH] vm-virtio: Update backend feature set for vhost-user-net

Regarding vhost-user-net, there are features in avail_features
and acked_features, like VIRTIO_NET_F_MAC which is required by
driver and device to transfer mac address through config space,
but not needed by backend, like ovs+dpdk, so it's necessary to
adjust backend_features based on acked_features before calling
set_features() API.

This fix is to record backend_features in vhost-user-net to avoid
requesting it twice.

Signed-off-by: Cathy Zhang <cathy.zhang@intel.com>
---
 vm-virtio/src/vhost_user/net.rs | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/vm-virtio/src/vhost_user/net.rs b/vm-virtio/src/vhost_user/net.rs
index 014006620..21823349e 100644
--- a/vm-virtio/src/vhost_user/net.rs
+++ b/vm-virtio/src/vhost_user/net.rs
@@ -33,6 +33,7 @@ pub struct Net {
     kill_evt: EventFd,
     avail_features: u64,
     acked_features: u64,
+    backend_features: u64,
     config_space: Vec<u8>,
     queue_sizes: Vec<u16>,
 }
@@ -79,7 +80,7 @@ impl<'a> Net {
             .map_err(Error::VhostUserSetFeatures)?;
 
         let mut acked_features = 0;
-        if backend_features & VhostUserVirtioFeatures::PROTOCOL_FEATURES.bits() != 0 {
+        if avail_features & VhostUserVirtioFeatures::PROTOCOL_FEATURES.bits() != 0 {
             acked_features |= VhostUserVirtioFeatures::PROTOCOL_FEATURES.bits();
             vhost_user_net
                 .get_protocol_features()
@@ -106,6 +107,7 @@ impl<'a> Net {
             kill_evt,
             avail_features,
             acked_features,
+            backend_features,
             config_space,
             queue_sizes: vec![vu_cfg.queue_size; vu_cfg.num_queues],
         })
@@ -201,7 +203,7 @@ impl VirtioDevice for Net {
             &mem.read().unwrap(),
             queues,
             queue_evts,
-            self.acked_features,
+            self.acked_features & self.backend_features,
         )
         .map_err(ActivateError::VhostUserNetSetup)?;