Merge remote-tracking branch 'remotes/aperard/tags/pull-xen-20201020' into staging

Xen queue

* cleanup patches.
* improve xen backend setup performance when other xen guests are
  running/booting.
* improve xen guest migration when running in a stubdomain.

# gpg: Signature made Tue 20 Oct 2020 10:55:11 BST
# gpg:                using RSA key F80C006308E22CFD8A92E7980CF5572FD7FB55AF
# gpg:                issuer "anthony.perard@citrix.com"
# gpg: Good signature from "Anthony PERARD <anthony.perard@gmail.com>" [marginal]
# gpg:                 aka "Anthony PERARD <anthony.perard@citrix.com>" [marginal]
# gpg: WARNING: This key is not certified with sufficiently trusted signatures!
# gpg:          It is not certain that the signature belongs to the owner.
# Primary key fingerprint: 5379 2F71 024C 600F 778A  7161 D8D5 7199 DF83 42C8
#      Subkey fingerprint: F80C 0063 08E2 2CFD 8A92  E798 0CF5 572F D7FB 55AF

* remotes/aperard/tags/pull-xen-20201020:
  hw/xen: Set suppress-vmdesc for Xen machines
  xen-bus: reduce scope of backend watch
  xen: Rename XENBACKEND_DEVICE to XENBACKEND
  xen: xenguest is not used so is not needed

Signed-off-by: Peter Maydell <peter.maydell@linaro.org>

2 files changed, 43 insertions, 8 deletions

diff --git a/hw/xen/xen-backend.c b/hw/xen/xen-backend.c
index 10199fb58d..5b0fb76eae 100644
--- a/hw/xen/xen-backend.c
+++ b/hw/xen/xen-backend.c
@@ -41,6 +41,12 @@ static void xen_backend_table_add(XenBackendImpl *impl)
     g_hash_table_insert(xen_backend_table_get(), (void *)impl->type, impl);
 }
 
+static const char **xen_backend_table_keys(unsigned int *count)
+{
+    return (const char **)g_hash_table_get_keys_as_array(
+        xen_backend_table_get(), count);
+}
+
 static const XenBackendImpl *xen_backend_table_lookup(const char *type)
 {
     return g_hash_table_lookup(xen_backend_table_get(), type);
@@ -70,6 +76,11 @@ void xen_backend_register(const XenBackendInfo *info)
     xen_backend_table_add(impl);
 }
 
+const char **xen_backend_get_types(unsigned int *count)
+{
+    return xen_backend_table_keys(count);
+}
+
 static QLIST_HEAD(, XenBackendInstance) backend_list;
 
 static void xen_backend_list_add(XenBackendInstance *backend)
diff --git a/hw/xen/xen-bus.c b/hw/xen/xen-bus.c
index 9ce1c9540b..8c588920d9 100644
--- a/hw/xen/xen-bus.c
+++ b/hw/xen/xen-bus.c
@@ -430,7 +430,15 @@ static void xen_bus_unrealize(BusState *bus)
     trace_xen_bus_unrealize();
 
     if (xenbus->backend_watch) {
-        xen_bus_remove_watch(xenbus, xenbus->backend_watch, NULL);
+        unsigned int i;
+
+        for (i = 0; i < xenbus->backend_types; i++) {
+            if (xenbus->backend_watch[i]) {
+                xen_bus_remove_watch(xenbus, xenbus->backend_watch[i], NULL);
+            }
+        }
+
+        g_free(xenbus->backend_watch);
         xenbus->backend_watch = NULL;
     }
 
@@ -446,8 +454,11 @@ static void xen_bus_unrealize(BusState *bus)
 
 static void xen_bus_realize(BusState *bus, Error **errp)
 {
+    char *key = g_strdup_printf("%u", xen_domid);
     XenBus *xenbus = XEN_BUS(bus);
     unsigned int domid;
+    const char **type;
+    unsigned int i;
     Error *local_err = NULL;
 
     trace_xen_bus_realize();
@@ -469,19 +480,32 @@ static void xen_bus_realize(BusState *bus, Error **errp)
 
     module_call_init(MODULE_INIT_XEN_BACKEND);
 
-    xenbus->backend_watch =
-        xen_bus_add_watch(xenbus, "", /* domain root node */
-                          "backend", xen_bus_backend_changed, &local_err);
-    if (local_err) {
-        /* This need not be treated as a hard error so don't propagate */
-        error_reportf_err(local_err,
-                          "failed to set up enumeration watch: ");
+    type = xen_backend_get_types(&xenbus->backend_types);
+    xenbus->backend_watch = g_new(XenWatch *, xenbus->backend_types);
+
+    for (i = 0; i < xenbus->backend_types; i++) {
+        char *node = g_strdup_printf("backend/%s", type[i]);
+
+        xenbus->backend_watch[i] =
+            xen_bus_add_watch(xenbus, node, key, xen_bus_backend_changed,
+                              &local_err);
+        if (local_err) {
+            /* This need not be treated as a hard error so don't propagate */
+            error_reportf_err(local_err,
+                              "failed to set up '%s' enumeration watch: ",
+                              type[i]);
+        }
+
+        g_free(node);
     }
 
+    g_free(type);
+    g_free(key);
     return;
 
 fail:
     xen_bus_unrealize(bus);
+    g_free(key);
 }
 
 static void xen_bus_unplug_request(HotplugHandler *hotplug,