virtio-net: make VirtIOFeature usable for other virtio devices

In order to use VirtIOFeature also in other virtio devices, we move
its declaration and the endof() macro (renamed in virtio_endof())
in virtio.h.
We add virtio_feature_get_config_size() function to iterate the array
of VirtIOFeature and to return the config size depending on the
features enabled. (as virtio_net_set_config_size() did)

Suggested-by: Michael S. Tsirkin <mst@redhat.com>
Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
Signed-off-by: Stefano Garzarella <sgarzare@redhat.com>
Message-id: 20190221103314.58500-5-sgarzare@redhat.com
Message-Id: <20190221103314.58500-5-sgarzare@redhat.com>
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>

hw/net/virtio-net.c

@@ -82,29 +82,17 @@ static inline __virtio16 *virtio_net_rsc_ext_num_dupacks(
 
 #endif
 
-/*
- * Calculate the number of bytes up to and including the given 'field' of
- * 'container'.
- */
-#define endof(container, field) \
-    (offsetof(container, field) + sizeof_field(container, field))
-
-typedef struct VirtIOFeature {
-    uint64_t flags;
-    size_t end;
-} VirtIOFeature;
-
 static VirtIOFeature feature_sizes[] = {
     {.flags = 1ULL << VIRTIO_NET_F_MAC,
-     .end = endof(struct virtio_net_config, mac)},
+     .end = virtio_endof(struct virtio_net_config, mac)},
     {.flags = 1ULL << VIRTIO_NET_F_STATUS,
-     .end = endof(struct virtio_net_config, status)},
+     .end = virtio_endof(struct virtio_net_config, status)},
     {.flags = 1ULL << VIRTIO_NET_F_MQ,
-     .end = endof(struct virtio_net_config, max_virtqueue_pairs)},
+     .end = virtio_endof(struct virtio_net_config, max_virtqueue_pairs)},
     {.flags = 1ULL << VIRTIO_NET_F_MTU,
-     .end = endof(struct virtio_net_config, mtu)},
+     .end = virtio_endof(struct virtio_net_config, mtu)},
     {.flags = 1ULL << VIRTIO_NET_F_SPEED_DUPLEX,
-     .end = endof(struct virtio_net_config, duplex)},
+     .end = virtio_endof(struct virtio_net_config, duplex)},
     {}
 };
 
@@ -2580,15 +2568,10 @@ static void virtio_net_guest_notifier_mask(VirtIODevice *vdev, int idx,
 
 static void virtio_net_set_config_size(VirtIONet *n, uint64_t host_features)
 {
-    int i, config_size = 0;
     virtio_add_feature(&host_features, VIRTIO_NET_F_MAC);
 
-    for (i = 0; feature_sizes[i].flags != 0; i++) {
+    n->config_size = virtio_feature_get_config_size(feature_sizes,
-        if (host_features & feature_sizes[i].flags) {
+                                                    host_features);
-            config_size = MAX(feature_sizes[i].end, config_size);
-        }
-    }
-    n->config_size = config_size;
 }
 
 void virtio_net_set_netclient_name(VirtIONet *n, const char *name,

hw/virtio/virtio.c

@@ -2036,6 +2036,21 @@ int virtio_set_features(VirtIODevice *vdev, uint64_t val)
     return ret;
 }
 
+size_t virtio_feature_get_config_size(VirtIOFeature *feature_sizes,
+                                      uint64_t host_features)
+{
+    size_t config_size = 0;
+    int i;
+
+    for (i = 0; feature_sizes[i].flags != 0; i++) {
+        if (host_features & feature_sizes[i].flags) {
+            config_size = MAX(feature_sizes[i].end, config_size);
+        }
+    }
+
+    return config_size;
+}
+
 int virtio_load(VirtIODevice *vdev, QEMUFile *f, int version_id)
 {
     int i, ret;

include/hw/virtio/virtio.h

@@ -37,6 +37,21 @@ static inline hwaddr vring_align(hwaddr addr,
     return QEMU_ALIGN_UP(addr, align);
 }
 
+/*
+ * Calculate the number of bytes up to and including the given 'field' of
+ * 'container'.
+ */
+#define virtio_endof(container, field) \
+    (offsetof(container, field) + sizeof_field(container, field))
+
+typedef struct VirtIOFeature {
+    uint64_t flags;
+    size_t end;
+} VirtIOFeature;
+
+size_t virtio_feature_get_config_size(VirtIOFeature *features,
+                                      uint64_t host_features);
+
 typedef struct VirtQueue VirtQueue;
 
 #define VIRTQUEUE_MAX_SIZE 1024