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: Wang Yufei <james.wangyufei@huawei.com>
Signed-off-by: Jiri Denemark <jdenemar@redhat.com>
(cherry picked from commit 0196845d3abd0d914cf11f7ad6c19df8b47c32ed)

Conflicts:
  missing support for WebSockets and listen address
  virAsprintf doesn't report OOM

	src/qemu/qemu_command.h
	src/qemu/qemu_conf.h
	src/qemu/qemu_driver.c
	src/qemu/qemu_migration.c

src/qemu/qemu_command.h

@@ -48,6 +48,8 @@
 # define QEMU_REMOTE_PORT_MIN  5900
 # define QEMU_REMOTE_PORT_MAX  65535
 
+# define QEMU_MIGRATION_PORT_MIN 49152
+# define QEMU_MIGRATION_PORT_MAX 49215
 
 virCommandPtr qemuBuildCommandLine(virConnectPtr conn,
                                    virQEMUDriverPtr driver,

src/qemu/qemu_conf.h

@@ -210,6 +210,9 @@ struct _virQEMUDriver {
     /* Immutable pointer, self-locking APIs */
     virPortAllocatorPtr remotePorts;
 
+    /* Immutable pointer, self-locking APIs */
+    virPortAllocatorPtr migrationPorts;
+
     /* Immutable pointer, lockless APIs*/
     virSysinfoDefPtr hostsysinfo;
 
@@ -231,9 +234,6 @@ struct _qemuDomainCmdlineDef {
     char **env_value;
 };
 
-/* Port numbers used for KVM migration. */
-# define QEMUD_MIGRATION_FIRST_PORT 49152
-# define QEMUD_MIGRATION_NUM_PORTS 64
 
 
 virQEMUDriverConfigPtr virQEMUDriverConfigNew(bool privileged);

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

@@ -662,6 +662,11 @@ qemuStateInitialize(bool privileged,
                              cfg->remotePortMax)) == 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;
 
@@ -951,6 +956,7 @@ qemuStateCleanup(void) {
 
     virObjectUnref(qemu_driver->domains);
     virObjectUnref(qemu_driver->remotePorts);
+    virObjectUnref(qemu_driver->migrationPorts);
 
     virObjectUnref(qemu_driver->xmlopt);
 

src/qemu/qemu_migration.c

@@ -1998,6 +1998,9 @@ 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);
@@ -2013,7 +2016,8 @@ qemuMigrationPrepareAny(virQEMUDriverPtr driver,
                         const char *dname,
                         const char *dom_xml,
                         virStreamPtr st,
-                        unsigned int port,
+                        unsigned short port,
+                        bool autoPort,
                         unsigned long flags)
 {
     virDomainDefPtr def = NULL;
@@ -2277,6 +2281,8 @@ done:
         goto cleanup;
     }
 
+    if (autoPort)
+        priv->migrationPort = port;
     ret = 0;
 
 cleanup:
@@ -2340,7 +2346,7 @@ qemuMigrationPrepareTunnel(virQEMUDriverPtr driver,
 
     ret = qemuMigrationPrepareAny(driver, dconn, cookiein, cookieinlen,
                                   cookieout, cookieoutlen, dname, dom_xml,
-                                  st, 0, flags);
+                                  st, 0, false, flags);
     return ret;
 }
 
@@ -2358,8 +2364,8 @@ qemuMigrationPrepareDirect(virQEMUDriverPtr driver,
                            const char *dom_xml,
                            unsigned long flags)
 {
-    static int port = 0;
+    unsigned short port = 0;
-    int this_port;
+    bool autoPort = true;
     char *hostname = NULL;
     const char *p;
     char *uri_str = NULL;
@@ -2384,8 +2390,14 @@ 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 (virPortAllocatorAcquire(driver->migrationPorts, &port) < 0) {
-        if (port == QEMUD_MIGRATION_NUM_PORTS) 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)) == NULL)
@@ -2404,7 +2416,7 @@ 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) {
             virReportOOMError();
             goto cleanup;
         }
@@ -2444,19 +2456,24 @@ qemuMigrationPrepareDirect(virQEMUDriverPtr driver,
         }
 
         if (uri->port == 0) {
-            /* Generate a port */
+            if (virPortAllocatorAcquire(driver->migrationPorts, &port) < 0) {
-            this_port = QEMUD_MIGRATION_FIRST_PORT + port++;
+                goto cleanup;
-            if (port == QEMUD_MIGRATION_NUM_PORTS)
+            } else if (!port) {
-                port = 0;
+                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) {
                 virReportOOMError();
                 goto cleanup;
             }
 
         } else {
-            this_port = uri->port;
+            port = uri->port;
+            autoPort = false;
         }
     }
 
@@ -2465,12 +2482,15 @@ qemuMigrationPrepareDirect(virQEMUDriverPtr driver,
 
     ret = qemuMigrationPrepareAny(driver, dconn, cookiein, cookieinlen,
                                   cookieout, cookieoutlen, dname, dom_xml,
-                                  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;
 }
 
@@ -3962,6 +3982,8 @@ qemuMigrationFinish(virQEMUDriverPtr driver,
         }
 
         qemuMigrationStopNBDServer(driver, vm, mig);
+        virPortAllocatorRelease(driver->migrationPorts, priv->migrationPort);
+        priv->migrationPort = 0;
 
         if (flags & VIR_MIGRATE_PERSIST_DEST) {
             virDomainDefPtr vmdef;