vhost-vsock: handle common features in vhost-vsock-common

virtio-vsock features, like VIRTIO_VSOCK_F_SEQPACKET, can be handled
by vhost-vsock-common parent class. In this way, we can reuse the
same code for all virtio-vsock backends (i.e. vhost-vsock,
vhost-user-vsock).

Let's move `seqpacket` property to vhost-vsock-common class, add
vhost_vsock_common_get_features() used by children, and disable
`seqpacket` for vhost-user-vsock device for machine types < 6.2.

The behavior of vhost-vsock device doesn't change; vhost-user-vsock
device now supports `seqpacket` property.

Signed-off-by: Stefano Garzarella <sgarzare@redhat.com>
Message-Id: <20210921161642.206461-3-sgarzare@redhat.com>
Reviewed-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>

hw/core/machine.c

@@ -37,7 +37,9 @@
 #include "hw/virtio/virtio.h"
 #include "hw/virtio/virtio-pci.h"
 
-GlobalProperty hw_compat_6_1[] = {};
+GlobalProperty hw_compat_6_1[] = {
+    { "vhost-user-vsock-device", "seqpacket", "off" },
+};
 const size_t hw_compat_6_1_len = G_N_ELEMENTS(hw_compat_6_1);
 
 GlobalProperty hw_compat_6_0[] = {

hw/virtio/vhost-user-vsock.c

@@ -81,7 +81,9 @@ static uint64_t vuv_get_features(VirtIODevice *vdev,
 {
     VHostVSockCommon *vvc = VHOST_VSOCK_COMMON(vdev);
 
-    return vhost_get_features(&vvc->vhost_dev, user_feature_bits, features);
+    features = vhost_get_features(&vvc->vhost_dev, user_feature_bits, features);
+
+    return vhost_vsock_common_get_features(vdev, features, errp);
 }
 
 static const VMStateDescription vuv_vmstate = {

hw/virtio/vhost-vsock-common.c

@@ -18,6 +18,30 @@
 #include "qemu/iov.h"
 #include "monitor/monitor.h"
 
+const int feature_bits[] = {
+    VIRTIO_VSOCK_F_SEQPACKET,
+    VHOST_INVALID_FEATURE_BIT
+};
+
+uint64_t vhost_vsock_common_get_features(VirtIODevice *vdev, uint64_t features,
+                                         Error **errp)
+{
+    VHostVSockCommon *vvc = VHOST_VSOCK_COMMON(vdev);
+
+    if (vvc->seqpacket != ON_OFF_AUTO_OFF) {
+        virtio_add_feature(&features, VIRTIO_VSOCK_F_SEQPACKET);
+    }
+
+    features = vhost_get_features(&vvc->vhost_dev, feature_bits, features);
+
+    if (vvc->seqpacket == ON_OFF_AUTO_ON &&
+        !virtio_has_feature(features, VIRTIO_VSOCK_F_SEQPACKET)) {
+        error_setg(errp, "vhost-vsock backend doesn't support seqpacket");
+    }
+
+    return features;
+}
+
 int vhost_vsock_common_start(VirtIODevice *vdev)
 {
     VHostVSockCommon *vvc = VHOST_VSOCK_COMMON(vdev);
@@ -231,11 +255,18 @@ void vhost_vsock_common_unrealize(VirtIODevice *vdev)
     virtio_cleanup(vdev);
 }
 
+static Property vhost_vsock_common_properties[] = {
+    DEFINE_PROP_ON_OFF_AUTO("seqpacket", VHostVSockCommon, seqpacket,
+                            ON_OFF_AUTO_AUTO),
+    DEFINE_PROP_END_OF_LIST(),
+};
+
 static void vhost_vsock_common_class_init(ObjectClass *klass, void *data)
 {
     DeviceClass *dc = DEVICE_CLASS(klass);
     VirtioDeviceClass *vdc = VIRTIO_DEVICE_CLASS(klass);
 
+    device_class_set_props(dc, vhost_vsock_common_properties);
     set_bit(DEVICE_CATEGORY_MISC, dc->categories);
     vdc->guest_notifier_mask = vhost_vsock_common_guest_notifier_mask;
     vdc->guest_notifier_pending = vhost_vsock_common_guest_notifier_pending;

hw/virtio/vhost-vsock.c

@@ -21,11 +21,6 @@
 #include "hw/virtio/vhost-vsock.h"
 #include "monitor/monitor.h"
 
-const int feature_bits[] = {
-    VIRTIO_VSOCK_F_SEQPACKET,
-    VHOST_INVALID_FEATURE_BIT
-};
-
 static void vhost_vsock_get_config(VirtIODevice *vdev, uint8_t *config)
 {
     VHostVSock *vsock = VHOST_VSOCK(vdev);
@@ -113,22 +108,7 @@ static uint64_t vhost_vsock_get_features(VirtIODevice *vdev,
                                          uint64_t requested_features,
                                          Error **errp)
 {
-    VHostVSockCommon *vvc = VHOST_VSOCK_COMMON(vdev);
-    VHostVSock *vsock = VHOST_VSOCK(vdev);
-
-    if (vsock->seqpacket != ON_OFF_AUTO_OFF) {
-        virtio_add_feature(&requested_features, VIRTIO_VSOCK_F_SEQPACKET);
-    }
-
-    requested_features = vhost_get_features(&vvc->vhost_dev, feature_bits,
-                                            requested_features);
-
-    if (vsock->seqpacket == ON_OFF_AUTO_ON &&
-        !virtio_has_feature(requested_features, VIRTIO_VSOCK_F_SEQPACKET)) {
-        error_setg(errp, "vhost-vsock backend doesn't support seqpacket");
-    }
-
-    return requested_features;
+    return vhost_vsock_common_get_features(vdev, requested_features, errp);
 }
 
 static const VMStateDescription vmstate_virtio_vhost_vsock = {
@@ -229,8 +209,6 @@ static void vhost_vsock_device_unrealize(DeviceState *dev)
 static Property vhost_vsock_properties[] = {
     DEFINE_PROP_UINT64("guest-cid", VHostVSock, conf.guest_cid, 0),
     DEFINE_PROP_STRING("vhostfd", VHostVSock, conf.vhostfd),
-    DEFINE_PROP_ON_OFF_AUTO("seqpacket", VHostVSock, seqpacket,
-                            ON_OFF_AUTO_AUTO),
     DEFINE_PROP_END_OF_LIST(),
 };
 

include/hw/virtio/vhost-vsock-common.h

@@ -35,6 +35,9 @@ struct VHostVSockCommon {
     VirtQueue *trans_vq;
 
     QEMUTimer *post_load_timer;
+
+    /* features */
+    OnOffAuto seqpacket;
 };
 
 int vhost_vsock_common_start(VirtIODevice *vdev);
@@ -43,5 +46,7 @@ int vhost_vsock_common_pre_save(void *opaque);
 int vhost_vsock_common_post_load(void *opaque, int version_id);
 void vhost_vsock_common_realize(VirtIODevice *vdev, const char *name);
 void vhost_vsock_common_unrealize(VirtIODevice *vdev);
+uint64_t vhost_vsock_common_get_features(VirtIODevice *vdev, uint64_t features,
+                                         Error **errp);
 
 #endif /* _QEMU_VHOST_VSOCK_COMMON_H */

include/hw/virtio/vhost-vsock.h

@@ -30,9 +30,6 @@ struct VHostVSock {
     VHostVSockCommon parent;
     VHostVSockConf conf;
 
-    /* features */
-    OnOffAuto seqpacket;
-
     /*< public >*/
 };