Introduce NBD migration cookie

This migration cookie is meant for two purposes. The first is to be sent
in begin phase from source to destination to let it know we support new
implementation of VIR_MIGRATE_NON_SHARED_{DISK,INC} so destination can
start NBD server. Then, the second purpose is, destination can let us
know, on which port the NBD server is running.

src/qemu/qemu_domain.h

@@ -156,6 +156,7 @@ struct _qemuDomainObjPrivate {
 
     unsigned long migMaxBandwidth;
     char *origname;
+    int nbdPort; /* Port used for migration with NBD */
 
     virChrdevsPtr devs;
 

src/qemu/qemu_migration.c

@@ -74,6 +74,7 @@ enum qemuMigrationCookieFlags {
     QEMU_MIGRATION_COOKIE_FLAG_LOCKSTATE,
     QEMU_MIGRATION_COOKIE_FLAG_PERSISTENT,
     QEMU_MIGRATION_COOKIE_FLAG_NETWORK,
+    QEMU_MIGRATION_COOKIE_FLAG_NBD,
 
     QEMU_MIGRATION_COOKIE_FLAG_LAST
 };
@@ -81,13 +82,18 @@ enum qemuMigrationCookieFlags {
 VIR_ENUM_DECL(qemuMigrationCookieFlag);
 VIR_ENUM_IMPL(qemuMigrationCookieFlag,
               QEMU_MIGRATION_COOKIE_FLAG_LAST,
-              "graphics", "lockstate", "persistent", "network");
+              "graphics",
+              "lockstate",
+              "persistent",
+              "network",
+              "nbd");
 
 enum qemuMigrationCookieFeatures {
     QEMU_MIGRATION_COOKIE_GRAPHICS  = (1 << QEMU_MIGRATION_COOKIE_FLAG_GRAPHICS),
     QEMU_MIGRATION_COOKIE_LOCKSTATE = (1 << QEMU_MIGRATION_COOKIE_FLAG_LOCKSTATE),
     QEMU_MIGRATION_COOKIE_PERSISTENT = (1 << QEMU_MIGRATION_COOKIE_FLAG_PERSISTENT),
     QEMU_MIGRATION_COOKIE_NETWORK = (1 << QEMU_MIGRATION_COOKIE_FLAG_NETWORK),
+    QEMU_MIGRATION_COOKIE_NBD = (1 << QEMU_MIGRATION_COOKIE_FLAG_NBD),
 };
 
 typedef struct _qemuMigrationCookieGraphics qemuMigrationCookieGraphics;
@@ -121,6 +127,12 @@ struct _qemuMigrationCookieNetwork {
     qemuMigrationCookieNetDataPtr net;
 };
 
+typedef struct _qemuMigrationCookieNBD qemuMigrationCookieNBD;
+typedef qemuMigrationCookieNBD *qemuMigrationCookieNBDPtr;
+struct _qemuMigrationCookieNBD {
+    int port; /* on which port does NBD server listen for incoming data */
+};
+
 typedef struct _qemuMigrationCookie qemuMigrationCookie;
 typedef qemuMigrationCookie *qemuMigrationCookiePtr;
 struct _qemuMigrationCookie {
@@ -149,6 +161,9 @@ struct _qemuMigrationCookie {
 
     /* If (flags & QEMU_MIGRATION_COOKIE_NETWORK) */
     qemuMigrationCookieNetworkPtr network;
+
+    /* If (flags & QEMU_MIGRATION_COOKIE_NBD) */
+    qemuMigrationCookieNBDPtr nbd;
 };
 
 static void qemuMigrationCookieGraphicsFree(qemuMigrationCookieGraphicsPtr grap)
@@ -194,6 +209,7 @@ static void qemuMigrationCookieFree(qemuMigrationCookiePtr mig)
     VIR_FREE(mig->name);
     VIR_FREE(mig->lockState);
     VIR_FREE(mig->lockDriver);
+    VIR_FREE(mig->nbd);
     VIR_FREE(mig);
 }
 
@@ -504,6 +520,27 @@ qemuMigrationCookieAddNetwork(qemuMigrationCookiePtr mig,
 }
 
 
+static int
+qemuMigrationCookieAddNBD(qemuMigrationCookiePtr mig,
+                          virQEMUDriverPtr driver ATTRIBUTE_UNUSED,
+                          virDomainObjPtr vm)
+{
+    qemuDomainObjPrivatePtr priv = vm->privateData;
+
+    /* It is not a bug if there already is a NBD data */
+    if (!mig->nbd &&
+        VIR_ALLOC(mig->nbd) < 0) {
+        virReportOOMError();
+        return -1;
+    }
+
+    mig->nbd->port = priv->nbdPort;
+    mig->flags |= QEMU_MIGRATION_COOKIE_NBD;
+
+    return 0;
+}
+
+
 static void qemuMigrationCookieGraphicsXMLFormat(virBufferPtr buf,
                                                  qemuMigrationCookieGraphicsPtr grap)
 {
@@ -606,6 +643,13 @@ qemuMigrationCookieXMLFormat(virQEMUDriverPtr driver,
     if ((mig->flags & QEMU_MIGRATION_COOKIE_NETWORK) && mig->network)
         qemuMigrationCookieNetworkXMLFormat(buf, mig->network);
 
+    if ((mig->flags & QEMU_MIGRATION_COOKIE_NBD) && mig->nbd) {
+        virBufferAddLit(buf, "  <nbd");
+        if (mig->nbd->port)
+            virBufferAsprintf(buf, " port='%d'", mig->nbd->port);
+        virBufferAddLit(buf, "/>\n");
+    }
+
     virBufferAddLit(buf, "</qemu-migration>\n");
     return 0;
 }
@@ -889,6 +933,26 @@ qemuMigrationCookieXMLParse(qemuMigrationCookiePtr mig,
         (!(mig->network = qemuMigrationCookieNetworkXMLParse(ctxt))))
         goto error;
 
+    if (flags & QEMU_MIGRATION_COOKIE_NBD &&
+        virXPathBoolean("boolean(./nbd)", ctxt)) {
+        char *port;
+
+        if (VIR_ALLOC(mig->nbd) < 0) {
+            virReportOOMError();
+            goto error;
+        }
+
+        port = virXPathString("string(./nbd/@port)", ctxt);
+        if (port && virStrToLong_i(port, NULL, 10, &mig->nbd->port) < 0) {
+            virReportError(VIR_ERR_INTERNAL_ERROR,
+                           _("Malformed nbd port '%s'"),
+                           port);
+            VIR_FREE(port);
+            goto error;
+        }
+        VIR_FREE(port);
+    }
+
     virObjectUnref(caps);
     return 0;
 
@@ -955,6 +1019,10 @@ qemuMigrationBakeCookie(qemuMigrationCookiePtr mig,
         return -1;
     }
 
+    if ((flags & QEMU_MIGRATION_COOKIE_NBD) &&
+        qemuMigrationCookieAddNBD(mig, driver, dom) < 0)
+        return -1;
+
     if (!(*cookieout = qemuMigrationCookieXMLFormatStr(driver, mig)))
         return -1;
 
@@ -1486,6 +1554,7 @@ char *qemuMigrationBegin(virQEMUDriverPtr driver,
     virDomainDefPtr def = NULL;
     qemuDomainObjPrivatePtr priv = vm->privateData;
     virCapsPtr caps = NULL;
+    unsigned int cookieFlags = QEMU_MIGRATION_COOKIE_LOCKSTATE;
 
     VIR_DEBUG("driver=%p, vm=%p, xmlin=%s, dname=%s,"
               " cookieout=%p, cookieoutlen=%p, flags=%lx",
@@ -1508,12 +1577,23 @@ char *qemuMigrationBegin(virQEMUDriverPtr driver,
     if (!(flags & VIR_MIGRATE_UNSAFE) && !qemuMigrationIsSafe(vm->def))
         goto cleanup;
 
+    if (flags & (VIR_MIGRATE_NON_SHARED_DISK | VIR_MIGRATE_NON_SHARED_INC) &&
+        virQEMUCapsGet(priv->qemuCaps, QEMU_CAPS_NBD_SERVER)) {
+        /* TODO support NBD for TUNNELLED migration */
+        if (flags & VIR_MIGRATE_TUNNELLED)
+            VIR_DEBUG("NBD in tunnelled migration is currently not supported");
+        else {
+            cookieFlags |= QEMU_MIGRATION_COOKIE_NBD;
+            priv->nbdPort = 0;
+        }
+    }
+
     if (!(mig = qemuMigrationEatCookie(driver, vm, NULL, 0, 0)))
         goto cleanup;
 
     if (qemuMigrationBakeCookie(mig, driver, vm,
                                 cookieout, cookieoutlen,
-                                QEMU_MIGRATION_COOKIE_LOCKSTATE) < 0)
+                                cookieFlags) < 0)
         goto cleanup;
 
     if (flags & VIR_MIGRATE_OFFLINE) {
@@ -1713,7 +1793,8 @@ qemuMigrationPrepareAny(virQEMUDriverPtr driver,
     origname = NULL;
 
     if (!(mig = qemuMigrationEatCookie(driver, vm, cookiein, cookieinlen,
-                                       QEMU_MIGRATION_COOKIE_LOCKSTATE)))
+                                       QEMU_MIGRATION_COOKIE_LOCKSTATE |
+                                       QEMU_MIGRATION_COOKIE_NBD)))
         goto cleanup;
 
     if (qemuMigrationJobStart(driver, vm, QEMU_ASYNC_JOB_MIGRATION_IN) < 0)
@@ -1776,8 +1857,20 @@ done:
     else
         cookieFlags = QEMU_MIGRATION_COOKIE_GRAPHICS;
 
-    if (qemuMigrationBakeCookie(mig, driver, vm, cookieout, cookieoutlen,
-                                cookieFlags) < 0) {
+    if (mig->nbd &&
+        flags & (VIR_MIGRATE_NON_SHARED_DISK | VIR_MIGRATE_NON_SHARED_INC) &&
+        virQEMUCapsGet(priv->qemuCaps, QEMU_CAPS_NBD_SERVER)) {
+        /* TODO support NBD for TUNNELLED migration */
+        if (flags & VIR_MIGRATE_TUNNELLED)
+            VIR_DEBUG("NBD in tunnelled migration is currently not supported");
+        else {
+            cookieFlags |= QEMU_MIGRATION_COOKIE_NBD;
+            priv->nbdPort = 0;
+        }
+    }
+
+    if (qemuMigrationBakeCookie(mig, driver, vm, cookieout,
+                                cookieoutlen, cookieFlags) < 0) {
         /* We could tear down the whole guest here, but
          * cookie data is (so far) non-critical, so that
          * seems a little harsh. We'll just warn for now.
@@ -2278,6 +2371,7 @@ qemuMigrationRun(virQEMUDriverPtr driver,
     int fd = -1;
     unsigned long migrate_speed = resource ? resource : priv->migMaxBandwidth;
     virErrorPtr orig_err = NULL;
+    unsigned int cookieFlags = 0;
 
     VIR_DEBUG("driver=%p, vm=%p, cookiein=%s, cookieinlen=%d, "
               "cookieout=%p, cookieoutlen=%p, flags=%lx, resource=%lu, "
@@ -2286,6 +2380,16 @@ qemuMigrationRun(virQEMUDriverPtr driver,
               cookieout, cookieoutlen, flags, resource,
               spec, spec->destType, spec->fwdType);
 
+    if (flags & VIR_MIGRATE_NON_SHARED_DISK) {
+        migrate_flags |= QEMU_MONITOR_MIGRATE_NON_SHARED_DISK;
+        cookieFlags |= QEMU_MIGRATION_COOKIE_NBD;
+    }
+
+    if (flags & VIR_MIGRATE_NON_SHARED_INC) {
+        migrate_flags |= QEMU_MONITOR_MIGRATE_NON_SHARED_INC;
+        cookieFlags |= QEMU_MIGRATION_COOKIE_NBD;
+    }
+
     if (virLockManagerPluginUsesState(driver->lockManager) &&
         !cookieout) {
         virReportError(VIR_ERR_INTERNAL_ERROR,
@@ -2295,8 +2399,9 @@ qemuMigrationRun(virQEMUDriverPtr driver,
         return -1;
     }
 
-    if (!(mig = qemuMigrationEatCookie(driver, vm, cookiein, cookieinlen,
-                                       QEMU_MIGRATION_COOKIE_GRAPHICS)))
+    mig = qemuMigrationEatCookie(driver, vm, cookiein, cookieinlen,
+                                 cookieFlags | QEMU_MIGRATION_COOKIE_GRAPHICS);
+    if (!mig)
         goto cleanup;
 
     if (qemuDomainMigrateGraphicsRelocate(driver, vm, mig) < 0)
@@ -2334,11 +2439,6 @@ qemuMigrationRun(virQEMUDriverPtr driver,
         goto cleanup;
     }
 
-    if (flags & VIR_MIGRATE_NON_SHARED_DISK)
-        migrate_flags |= QEMU_MONITOR_MIGRATE_NON_SHARED_DISK;
-
-    if (flags & VIR_MIGRATE_NON_SHARED_INC)
-        migrate_flags |= QEMU_MONITOR_MIGRATE_NON_SHARED_INC;
 
     /* connect to the destination qemu if needed */
     if (spec->destType == MIGRATION_DEST_CONNECT_HOST &&
@@ -2446,10 +2546,11 @@ cleanup:
         VIR_FORCE_CLOSE(fd);
     }
 
+    cookieFlags |= (QEMU_MIGRATION_COOKIE_PERSISTENT |
+                    QEMU_MIGRATION_COOKIE_NETWORK);
     if (ret == 0 &&
-        qemuMigrationBakeCookie(mig, driver, vm, cookieout, cookieoutlen,
-                                QEMU_MIGRATION_COOKIE_PERSISTENT |
-                                QEMU_MIGRATION_COOKIE_NETWORK) < 0) {
+        qemuMigrationBakeCookie(mig, driver, vm, cookieout,
+                                cookieoutlen, cookieFlags) < 0) {
         VIR_WARN("Unable to encode migration cookie");
     }