qemu: Avoid assigning unavailable migration ports

https://bugzilla.redhat.com/show_bug.cgi?id=1019053

When we migrate vms concurrently, there's a chance that libvirtd on
destination assigns the same port for different migrations, which will
lead to migration failure during prepare phase on destination. So we use
virPortAllocator here to solve the problem.
Signed-off-by: NWang Yufei <james.wangyufei@huawei.com>
Signed-off-by: NJiri Denemark <jdenemar@redhat.com>
(cherry picked from commit 0196845d)

Conflicts:
  missing support for changing the migration listen address
	src/qemu/qemu_migration.c

src/qemu/qemu_command.h

@@ -51,6 +51,9 @@
 # define QEMU_WEBSOCKET_PORT_MIN  5700
 # define QEMU_WEBSOCKET_PORT_MAX  65535
 
+# define QEMU_MIGRATION_PORT_MIN 49152
+# define QEMU_MIGRATION_PORT_MAX 49215
+
 typedef struct _qemuBuildCommandLineCallbacks qemuBuildCommandLineCallbacks;
 typedef qemuBuildCommandLineCallbacks *qemuBuildCommandLineCallbacksPtr;
 struct _qemuBuildCommandLineCallbacks {

src/qemu/qemu_conf.h

@@ -221,6 +221,9 @@ struct _virQEMUDriver {
     /* Immutable pointer, self-locking APIs */
     virPortAllocatorPtr webSocketPorts;
 
+    /* Immutable pointer, self-locking APIs */
+    virPortAllocatorPtr migrationPorts;
+
     /* Immutable pointer, lockless APIs*/
     virSysinfoDefPtr hostsysinfo;
 
@@ -242,9 +245,6 @@ struct _qemuDomainCmdlineDef {
     char **env_value;
 };
 
-/* Port numbers used for KVM migration. */
-# define QEMUD_MIGRATION_FIRST_PORT 49152
-# define QEMUD_MIGRATION_NUM_PORTS 64
 
 
 void qemuDomainCmdlineDefFree(qemuDomainCmdlineDefPtr def);

src/qemu/qemu_domain.h

@@ -160,6 +160,7 @@ struct _qemuDomainObjPrivate {
     unsigned long migMaxBandwidth;
     char *origname;
     int nbdPort; /* Port used for migration with NBD */
+    unsigned short migrationPort;
 
     virChrdevsPtr devs;
 

src/qemu/qemu_driver.c

@@ -687,6 +687,11 @@ qemuStateInitialize(bool privileged,
                              cfg->webSocketPortMax)) == NULL)
         goto error;
 
+    if ((qemu_driver->migrationPorts =
+         virPortAllocatorNew(QEMU_MIGRATION_PORT_MIN,
+                             QEMU_MIGRATION_PORT_MAX)) == NULL)
+        goto error;
+
     if (qemuSecurityInit(qemu_driver) < 0)
         goto error;
 
@@ -992,6 +997,7 @@ qemuStateCleanup(void) {
     virObjectUnref(qemu_driver->domains);
     virObjectUnref(qemu_driver->remotePorts);
     virObjectUnref(qemu_driver->webSocketPorts);
+    virObjectUnref(qemu_driver->migrationPorts);
 
     virObjectUnref(qemu_driver->xmlopt);
 

src/qemu/qemu_migration.c

@@ -2151,6 +2151,9 @@ qemuMigrationPrepareCleanup(virQEMUDriverPtr driver,
               qemuDomainJobTypeToString(priv->job.active),
               qemuDomainAsyncJobTypeToString(priv->job.asyncJob));
 
+    virPortAllocatorRelease(driver->migrationPorts, priv->migrationPort);
+    priv->migrationPort = 0;
+
     if (!qemuMigrationJobIsActive(vm, QEMU_ASYNC_JOB_MIGRATION_IN))
         return;
     qemuDomainObjDiscardAsyncJob(driver, vm);
@@ -2166,7 +2169,8 @@ qemuMigrationPrepareAny(virQEMUDriverPtr driver,
                         virDomainDefPtr *def,
                         const char *origname,
                         virStreamPtr st,
-                        unsigned int port,
+                        unsigned short port,
+                        bool autoPort,
                         unsigned long flags)
 {
     virDomainObjPtr vm = NULL;
@@ -2412,6 +2416,8 @@ done:
         goto cleanup;
     }
 
+    if (autoPort)
+        priv->migrationPort = port;
     ret = 0;
 
 cleanup:
@@ -2479,7 +2485,7 @@ qemuMigrationPrepareTunnel(virQEMUDriverPtr driver,
 
     ret = qemuMigrationPrepareAny(driver, dconn, cookiein, cookieinlen,
                                   cookieout, cookieoutlen, def, origname,
-                                  st, 0, flags);
+                                  st, 0, false, flags);
     return ret;
 }
 
@@ -2497,8 +2503,8 @@ qemuMigrationPrepareDirect(virQEMUDriverPtr driver,
                            const char *origname,
                            unsigned long flags)
 {
-    static int port = 0;
-    int this_port;
+    unsigned short port = 0;
+    bool autoPort = true;
     char *hostname = NULL;
     const char *p;
     char *uri_str = NULL;
@@ -2525,10 +2531,15 @@ qemuMigrationPrepareDirect(virQEMUDriverPtr driver,
      * to be a correct hostname which refers to the target machine).
      */
     if (uri_in == NULL) {
-        this_port = QEMUD_MIGRATION_FIRST_PORT + port++;
-        if (port == QEMUD_MIGRATION_NUM_PORTS) port = 0;
+        if (virPortAllocatorAcquire(driver->migrationPorts, &port) < 0) {
+            goto cleanup;
+        } else if (!port) {
+            virReportError(VIR_ERR_INTERNAL_ERROR, "%s",
+                           _("No migration port available within the "
+                             "configured range"));
+            goto cleanup;
+        }
 
-        /* Get hostname */
         if ((hostname = virGetHostname()) == NULL)
             goto cleanup;
 
@@ -2545,7 +2556,7 @@ qemuMigrationPrepareDirect(virQEMUDriverPtr driver,
          * new targets accept both syntaxes though.
          */
         /* Caller frees */
-        if (virAsprintf(uri_out, "tcp:%s:%d", hostname, this_port) < 0)
+        if (virAsprintf(uri_out, "tcp:%s:%d", hostname, port) < 0)
             goto cleanup;
     } else {
         /* Check the URI starts with "tcp:".  We will escape the
@@ -2581,17 +2592,22 @@ qemuMigrationPrepareDirect(virQEMUDriverPtr driver,
         }
 
         if (uri->port == 0) {
-            /* Generate a port */
-            this_port = QEMUD_MIGRATION_FIRST_PORT + port++;
-            if (port == QEMUD_MIGRATION_NUM_PORTS)
-                port = 0;
+            if (virPortAllocatorAcquire(driver->migrationPorts, &port) < 0) {
+                goto cleanup;
+            } else if (!port) {
+                virReportError(VIR_ERR_INTERNAL_ERROR, "%s",
+                               _("No migration port available within the "
+                                 "configured range"));
+                goto cleanup;
+            }
 
             /* Caller frees */
-            if (virAsprintf(uri_out, "%s:%d", uri_in, this_port) < 0)
+            if (virAsprintf(uri_out, "%s:%d", uri_in, port) < 0)
                 goto cleanup;
 
         } else {
-            this_port = uri->port;
+            port = uri->port;
+            autoPort = false;
         }
     }
 
@@ -2600,12 +2616,15 @@ qemuMigrationPrepareDirect(virQEMUDriverPtr driver,
 
     ret = qemuMigrationPrepareAny(driver, dconn, cookiein, cookieinlen,
                                   cookieout, cookieoutlen, def, origname,
-                                  NULL, this_port, flags);
+                                  NULL, port, autoPort, flags);
 cleanup:
     virURIFree(uri);
     VIR_FREE(hostname);
-    if (ret != 0)
+    if (ret != 0) {
         VIR_FREE(*uri_out);
+        if (autoPort)
+            virPortAllocatorRelease(driver->migrationPorts, port);
+    }
     return ret;
 }
 
@@ -4374,6 +4393,8 @@ qemuMigrationFinish(virQEMUDriverPtr driver,
         }
 
         qemuMigrationStopNBDServer(driver, vm, mig);
+        virPortAllocatorRelease(driver->migrationPorts, priv->migrationPort);
+        priv->migrationPort = 0;
 
         if (flags & VIR_MIGRATE_PERSIST_DEST) {
             virDomainDefPtr vmdef;