virtio-net: Store failover primary opts pointer locally

Instead of accessing the global QemuOptsList, which really belong to the
command line parser and shouldn't be accessed from devices, store a
pointer to the QemuOpts in a new VirtIONet field.

This is not the final state, but just an intermediate step to get rid of
QemuOpts in devices. It will later be replaced with an options QDict.

Before this patch, two "primary" devices could be hidden for the same
standby device, but only one of them would actually be enabled and the
other one would be kept hidden forever, so this doesn't make sense.
After this patch, configuring a second primary device is an error.

Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Message-Id: <20211008133442.141332-13-kwolf@redhat.com>
Reviewed-by: Michael S. Tsirkin <mst@redhat.com>
Tested-by: Peter Krempa <pkrempa@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>

1 files changed, 18 insertions, 8 deletions

diff --git a/hw/net/virtio-net.c b/hw/net/virtio-net.c
index a17d573..ed9a901 100644
--- a/hw/net/virtio-net.c
+++ b/hw/net/virtio-net.c
@@ -858,27 +858,24 @@ static DeviceState *failover_find_primary_device(VirtIONet *n)
 static void failover_add_primary(VirtIONet *n, Error **errp)
 {
     Error *err = NULL;
-    QemuOpts *opts;
-    char *id;
     DeviceState *dev = failover_find_primary_device(n);
 
     if (dev) {
         return;
     }
 
-    id = failover_find_primary_device_id(n);
-    if (!id) {
+    if (!n->primary_opts) {
         error_setg(errp, "Primary device not found");
         error_append_hint(errp, "Virtio-net failover will not work. Make "
                           "sure primary device has parameter"
                           " failover_pair_id=%s\n", n->netclient_name);
         return;
     }
-    opts = qemu_opts_find(qemu_find_opts("device"), id);
-    g_assert(opts); /* cannot be NULL because id was found using opts list */
-    dev = qdev_device_add(opts, &err);
+
+    dev = qdev_device_add(n->primary_opts, &err);
     if (err) {
-        qemu_opts_del(opts);
+        qemu_opts_del(n->primary_opts);
+        n->primary_opts = NULL;
     } else {
         object_unref(OBJECT(dev));
     }
@@ -3317,6 +3314,19 @@ static bool failover_hide_primary_device(DeviceListener *listener,
         return false;
     }
 
+    if (n->primary_opts) {
+        error_setg(errp, "Cannot attach more than one primary device to '%s'",
+                   n->netclient_name);
+        return false;
+    }
+
+    /*
+     * Having a weak reference here should be okay because a device can't be
+     * deleted while it's hidden. This will be replaced soon with a QDict that
+     * has a clearer ownership model.
+     */
+    n->primary_opts = device_opts;
+
     /* failover_primary_hidden is set during feature negotiation */
     return qatomic_read(&n->failover_primary_hidden);
 }