[Qemu-devel] [PATCH v2 10/16] vhost-pci-net: send the negotiated feature bits to the master

[Wei Wang <wei.w.wang@intel.com>]

The slave device actively sends the negotiated feature bits to
the master.

Signed-off-by: Wei Wang <wei.w.wang@intel.com>
---
 hw/net/vhost-pci-net.c              | 18 ++++++++++++++++++
 hw/virtio/vhost-pci-slave.c         | 22 ++++++++++++++++++++++
 include/hw/virtio/vhost-pci-slave.h |  2 ++
 3 files changed, 42 insertions(+)

diff --git a/hw/net/vhost-pci-net.c b/hw/net/vhost-pci-net.c
index 0235511..1379204 100644
--- a/hw/net/vhost-pci-net.c
+++ b/hw/net/vhost-pci-net.c
@@ -181,6 +181,24 @@ static uint64_t vpnet_get_features(VirtIODevice *vdev, uint64_t features,
 
 static void vpnet_set_features(VirtIODevice *vdev, uint64_t features)
 {
+    /*
+     * The implementation split the write of the 64-bit "features" into 2
+     * 32-bit writes, so the function is called twice. need_send is used to
+     * detect the second write which finishes the write of "features", and
+     * need to send to the remote device.
+     */
+    static bool need_send;
+    int ret;
+
+    if (need_send) {
+        need_send = 0;
+        ret = vp_slave_send_feature_bits(features);
+        if (ret < 0) {
+            error_report("%s failed to send feature bits", __func__);
+        }
+    } else {
+        need_send = 1;
+    }
 }
 
 static void vpnet_get_config(VirtIODevice *vdev, uint8_t *config)
diff --git a/hw/virtio/vhost-pci-slave.c b/hw/virtio/vhost-pci-slave.c
index ab1d06b..6cc9c21 100644
--- a/hw/virtio/vhost-pci-slave.c
+++ b/hw/virtio/vhost-pci-slave.c
@@ -122,6 +122,28 @@ static void vp_slave_set_features(VhostUserMsg *msg)
                            ~(1 << VHOST_USER_F_PROTOCOL_FEATURES);
 }
 
+static int vp_slave_send_u64(int request, uint64_t u64)
+{
+    VhostUserMsg msg = {
+        .request = request,
+        .flags = VHOST_USER_VERSION,
+        .payload.u64 = u64,
+        .size = sizeof(msg.payload.u64),
+    };
+
+    if (vp_slave_write(&vp_slave->chr_be, &msg) < 0) {
+        error_report("%s: failed to send", __func__);
+        return -1;
+    }
+
+    return 0;
+}
+
+int vp_slave_send_feature_bits(uint64_t features)
+{
+    return vp_slave_send_u64(VHOST_USER_SET_FEATURES, features);
+}
+
 static void vp_slave_event(void *opaque, int event)
 {
     switch (event) {
diff --git a/include/hw/virtio/vhost-pci-slave.h b/include/hw/virtio/vhost-pci-slave.h
index b5bf02a..ab21e70 100644
--- a/include/hw/virtio/vhost-pci-slave.h
+++ b/include/hw/virtio/vhost-pci-slave.h
@@ -56,6 +56,8 @@ extern int vhost_pci_slave_init(QemuOpts *opts);
 
 extern int vhost_pci_slave_cleanup(void);
 
+extern int vp_slave_send_feature_bits(uint64_t features);
+
 VhostPCIDev *get_vhost_pci_dev(void);
 
 #endif
-- 
2.7.4