vcpu: improve support for setting xen vcpu counts

Tested with RHEL 5.6 (xendConfigVersion 2, where xend_internal
controls live domains and xm_internal controls inactive domains).
Hopefully this works with xendConfigVersion 3 (where xend_internal
controls everything).

* src/xen/xen_driver.c (xenUnifiedDomainSetVcpusFlags): Support
more flags.
(xenUnifiedGetMaxVcpus): Export.
* src/xen/xm_internal.h (xenXMDomainSetVcpusFlags): New prototype.
* src/xen/xend_internal.h (xenDaemonDomainSetVcpusFlags): Likewise.
* src/xen/xen_driver.h (xenUnifiedGetMaxVcpus): Likewise.
* src/xen/xm_internal.c (xenXMDomainSetVcpusFlags): New function.
* src/xen/xend_internal.c (xenDaemonDomainSetVcpusFlags): Likewise.

src/xen/xen_driver.c

@@ -508,7 +508,7 @@ xenUnifiedIsSecure(virConnectPtr conn)
     return ret;
 }
 
-static int
+int
 xenUnifiedGetMaxVcpus (virConnectPtr conn, const char *type)
 {
     GET_PRIVATE(conn);
@@ -1073,36 +1073,62 @@ xenUnifiedDomainSetVcpusFlags (virDomainPtr dom, unsigned int nvcpus,
                                unsigned int flags)
 {
     GET_PRIVATE(dom->conn);
-    int i;
+    int ret;
+
+    virCheckFlags(VIR_DOMAIN_VCPU_LIVE |
+                  VIR_DOMAIN_VCPU_CONFIG |
+                  VIR_DOMAIN_VCPU_MAXIMUM, -1);
 
-    if (flags != VIR_DOMAIN_VCPU_LIVE) {
-        xenUnifiedError(VIR_ERR_INVALID_ARG, _("unsupported flags: (0x%x)"),
-                        flags);
+    /* At least one of LIVE or CONFIG must be set.  MAXIMUM cannot be
+     * mixed with LIVE.  */
+    if ((flags & (VIR_DOMAIN_VCPU_LIVE | VIR_DOMAIN_VCPU_CONFIG)) == 0 ||
+        (flags & (VIR_DOMAIN_VCPU_MAXIMUM | VIR_DOMAIN_VCPU_LIVE)) ==
+         (VIR_DOMAIN_VCPU_MAXIMUM | VIR_DOMAIN_VCPU_LIVE)) {
+        xenUnifiedError(VIR_ERR_INVALID_ARG,
+                        _("invalid flag combination: (0x%x)"), flags);
+        return -1;
+    }
+    if (!nvcpus || (unsigned short) nvcpus != nvcpus) {
+        xenUnifiedError(VIR_ERR_INVALID_ARG,
+                        _("argument out of range: %d"), nvcpus);
         return -1;
     }
 
     /* Try non-hypervisor methods first, then hypervisor direct method
      * as a last resort.
      */
-    for (i = 0; i < XEN_UNIFIED_NR_DRIVERS; ++i)
-        if (i != XEN_UNIFIED_HYPERVISOR_OFFSET &&
-            priv->opened[i] &&
-            drivers[i]->domainSetVcpus &&
-            drivers[i]->domainSetVcpus (dom, nvcpus) == 0)
-            return 0;
-
-    if (priv->opened[XEN_UNIFIED_HYPERVISOR_OFFSET] &&
-        drivers[XEN_UNIFIED_HYPERVISOR_OFFSET]->domainSetVcpus &&
-        drivers[XEN_UNIFIED_HYPERVISOR_OFFSET]->domainSetVcpus (dom, nvcpus) == 0)
-        return 0;
+    if (priv->opened[XEN_UNIFIED_XEND_OFFSET]) {
+        ret = xenDaemonDomainSetVcpusFlags(dom, nvcpus, flags);
+        if (ret != -2)
+            return ret;
+    }
+    if (priv->opened[XEN_UNIFIED_XM_OFFSET]) {
+        ret = xenXMDomainSetVcpusFlags(dom, nvcpus, flags);
+        if (ret != -2)
+            return ret;
+    }
+    if (flags == VIR_DOMAIN_VCPU_LIVE)
+        return xenHypervisorSetVcpus(dom, nvcpus);
 
+    xenUnifiedError(VIR_ERR_NO_SUPPORT, __FUNCTION__);
     return -1;
 }
 
 static int
 xenUnifiedDomainSetVcpus (virDomainPtr dom, unsigned int nvcpus)
 {
-    return xenUnifiedDomainSetVcpusFlags(dom, nvcpus, VIR_DOMAIN_VCPU_LIVE);
+    unsigned int flags = VIR_DOMAIN_VCPU_LIVE;
+    xenUnifiedPrivatePtr priv;
+
+    /* Per the documented API, it is hypervisor-dependent whether this
+     * affects just _LIVE or _LIVE|_CONFIG; in xen's case, that
+     * depends on xendConfigVersion.  */
+    if (dom) {
+        priv = dom->conn->privateData;
+        if (priv->xendConfigVersion >= 3)
+            flags |= VIR_DOMAIN_VCPU_CONFIG;
+    }
+    return xenUnifiedDomainSetVcpusFlags(dom, nvcpus, flags);
 }
 
 static int

src/xen/xen_driver.h

@@ -220,6 +220,7 @@ int  xenUnifiedRemoveDomainInfo(xenUnifiedDomainInfoListPtr info,
 void xenUnifiedDomainEventDispatch (xenUnifiedPrivatePtr priv,
                                     virDomainEventPtr event);
 unsigned long xenUnifiedVersion(void);
+int xenUnifiedGetMaxVcpus(virConnectPtr conn, const char *type);
 
 # ifndef PROXY
 void xenUnifiedLock(xenUnifiedPrivatePtr priv);

src/xen/xend_internal.c

@@ -3534,6 +3534,82 @@ xenDaemonLookupByID(virConnectPtr conn, int id) {
     return (NULL);
 }
 
+/**
+ * xenDaemonDomainSetVcpusFlags:
+ * @domain: pointer to domain object
+ * @nvcpus: the new number of virtual CPUs for this domain
+ * @flags: bitwise-ORd from virDomainVcpuFlags
+ *
+ * Change virtual CPUs allocation of domain according to flags.
+ *
+ * Returns 0 on success, -1 if an error message was issued, and -2 if
+ * the unified driver should keep trying.
+ */
+int
+xenDaemonDomainSetVcpusFlags(virDomainPtr domain, unsigned int vcpus,
+                             unsigned int flags)
+{
+    char buf[VIR_UUID_BUFLEN];
+    xenUnifiedPrivatePtr priv;
+    int max;
+
+    if ((domain == NULL) || (domain->conn == NULL) || (domain->name == NULL)
+        || (vcpus < 1)) {
+        virXendError(VIR_ERR_INVALID_ARG, __FUNCTION__);
+        return (-1);
+    }
+
+    priv = (xenUnifiedPrivatePtr) domain->conn->privateData;
+
+    if ((domain->id < 0 && priv->xendConfigVersion < 3) ||
+        (flags & VIR_DOMAIN_VCPU_MAXIMUM))
+        return -2;
+
+    /* With xendConfigVersion 2, only _LIVE is supported.  With
+     * xendConfigVersion 3, only _LIVE|_CONFIG is supported for
+     * running domains, or _CONFIG for inactive domains.  */
+    if (priv->xendConfigVersion < 3) {
+        if (flags & VIR_DOMAIN_VCPU_CONFIG) {
+            virXendError(VIR_ERR_OPERATION_INVALID, "%s",
+                         _("Xend version does not support modifying "
+                           "persistent config"));
+            return -1;
+        }
+    } else if (domain->id < 0) {
+        if (flags & VIR_DOMAIN_VCPU_LIVE) {
+            virXendError(VIR_ERR_OPERATION_INVALID, "%s",
+                         _("domain not running"));
+            return -1;
+        }
+    } else {
+        if ((flags & (VIR_DOMAIN_VCPU_LIVE | VIR_DOMAIN_VCPU_CONFIG)) !=
+            (VIR_DOMAIN_VCPU_LIVE | VIR_DOMAIN_VCPU_CONFIG)) {
+            virXendError(VIR_ERR_OPERATION_INVALID, "%s",
+                         _("Xend only supports modifying both live and "
+                           "persistent config"));
+        }
+    }
+
+    /* Unfortunately, xend_op does not validate whether this exceeds
+     * the maximum.  */
+    flags |= VIR_DOMAIN_VCPU_MAXIMUM;
+    if ((max = xenDaemonDomainGetVcpusFlags(domain, flags)) < 0) {
+        virXendError(VIR_ERR_OPERATION_INVALID, "%s",
+                     _("could not determin max vcpus for the domain"));
+        return -1;
+    }
+    if (vcpus > max) {
+        virXendError(VIR_ERR_INVALID_ARG,
+                     _("requested vcpus is greater than max allowable"
+                       " vcpus for the domain: %d > %d"), vcpus, max);
+        return -1;
+    }
+
+    snprintf(buf, sizeof(buf), "%d", vcpus);
+    return xend_op(domain->conn, domain->name, "op", "set_vcpus", "vcpus",
+                   buf, NULL);
+}
+
 /**
  * xenDaemonDomainSetVcpus:
  * @domain: pointer to domain object

src/xen/xend_internal.h

@@ -151,6 +151,9 @@ int xenDaemonDomainUndefine(virDomainPtr domain);
 
 int	xenDaemonDomainSetVcpus		(virDomainPtr domain,
                                          unsigned int vcpus);
+int	xenDaemonDomainSetVcpusFlags	(virDomainPtr domain,
+                                         unsigned int vcpus,
+                                         unsigned int flags);
 int	xenDaemonDomainPinVcpu		(virDomainPtr domain,
                                          unsigned int vcpu,
                                          unsigned char *cpumap,

src/xen/xm_internal.c

@@ -1670,6 +1670,89 @@ cleanup:
     return ret;
 }
 
+/*
+ * xenXMDomainSetVcpusFlags:
+ * @domain: pointer to domain object
+ * @nvcpus: number of vcpus
+ * @flags: bitwise-ORd from virDomainVcpuFlags
+ *
+ * Change virtual CPUs allocation of domain according to flags.
+ *
+ * Returns 0 on success, -1 if an error message was issued, and -2 if
+ * the unified driver should keep trying.
+ */
+int
+xenXMDomainSetVcpusFlags(virDomainPtr domain, unsigned int vcpus,
+                         unsigned int flags)
+{
+    xenUnifiedPrivatePtr priv;
+    const char *filename;
+    xenXMConfCachePtr entry;
+    int ret = -1;
+    int max;
+
+    if ((domain == NULL) || (domain->conn == NULL) || (domain->name == NULL)) {
+        xenXMError(VIR_ERR_INVALID_ARG, __FUNCTION__);
+        return -1;
+    }
+    if (domain->conn->flags & VIR_CONNECT_RO) {
+        xenXMError(VIR_ERR_OPERATION_DENIED, __FUNCTION__);
+        return -1;
+    }
+    if (domain->id != -1)
+        return -2;
+    if (flags & VIR_DOMAIN_VCPU_LIVE) {
+        xenXMError(VIR_ERR_OPERATION_INVALID, "%s",
+                   _("domain is not running"));
+        return -1;
+    }
+
+    priv = domain->conn->privateData;
+    xenUnifiedLock(priv);
+
+    if (!(filename = virHashLookup(priv->nameConfigMap, domain->name)))
+        goto cleanup;
+
+    if (!(entry = virHashLookup(priv->configCache, filename)))
+        goto cleanup;
+
+    /* Hypervisor maximum. */
+    if ((max = xenUnifiedGetMaxVcpus(domain->conn, NULL)) < 0) {
+        xenXMError(VIR_ERR_INTERNAL_ERROR, "%s",
+                   _("could not determin max vcpus for the domain"));
+        goto cleanup;
+    }
+    /* Can't specify a current larger than stored maximum; but
+     * reducing maximum can silently reduce current.  */
+    if (!(flags & VIR_DOMAIN_VCPU_MAXIMUM))
+        max = entry->def->maxvcpus;
+    if (vcpus > max) {
+        xenXMError(VIR_ERR_INVALID_ARG,
+                   _("requested vcpus is greater than max allowable"
+                     " vcpus for the domain: %d > %d"), vcpus, max);
+        goto cleanup;
+    }
+
+    if (flags & VIR_DOMAIN_VCPU_MAXIMUM) {
+        entry->def->maxvcpus = vcpus;
+        if (entry->def->vcpus > vcpus)
+            entry->def->vcpus = vcpus;
+    } else {
+        entry->def->vcpus = vcpus;
+    }
+
+    /* If this fails, should we try to undo our changes to the
+     * in-memory representation of the config file. I say not!
+     */
+    if (xenXMConfigSaveFile(domain->conn, entry->filename, entry->def) < 0)
+        goto cleanup;
+    ret = 0;
+
+cleanup:
+    xenUnifiedUnlock(priv);
+    return ret;
+}
+
 /**
  * xenXMDomainGetVcpusFlags:
  * @domain: pointer to domain object

src/xen/xm_internal.h

@@ -45,6 +45,8 @@ int xenXMDomainSetMemory(virDomainPtr domain, unsigned long memory);
 int xenXMDomainSetMaxMemory(virDomainPtr domain, unsigned long memory);
 unsigned long xenXMDomainGetMaxMemory(virDomainPtr domain);
 int xenXMDomainSetVcpus(virDomainPtr domain, unsigned int vcpus);
+int xenXMDomainSetVcpusFlags(virDomainPtr domain, unsigned int vcpus,
+                             unsigned int flags);
 int xenXMDomainGetVcpusFlags(virDomainPtr domain, unsigned int flags);
 int xenXMDomainPinVcpu(virDomainPtr domain, unsigned int vcpu,
                        unsigned char *cpumap, int maplen);