lib: Add API for specific vCPU hot(un)plug

Similarly to domainSetGuestVcpus this commit adds API which allows to
modify state of individual vcpus rather than just setting the count.

This allows to enable CPUs in specific guest NUMA nodes to achieve any
necessary configuration.

include/libvirt/libvirt-domain.h

@@ -4528,4 +4528,9 @@ int virDomainSetGuestVcpus(virDomainPtr domain,
                            int state,
                            unsigned int flags);
 
+int virDomainSetVcpu(virDomainPtr domain,
+                     const char *vcpumap,
+                     int state,
+                     unsigned int flags);
+
 #endif /* __VIR_LIBVIRT_DOMAIN_H__ */

src/driver-hypervisor.h

@@ -1251,6 +1251,12 @@ typedef int
                              int state,
                              unsigned int flags);
 
+typedef int
+(*virDrvDomainSetVcpu)(virDomainPtr domain,
+                       const char *cpumap,
+                       int state,
+                       unsigned int flags);
+
 typedef struct _virHypervisorDriver virHypervisorDriver;
 typedef virHypervisorDriver *virHypervisorDriverPtr;
 
@@ -1489,6 +1495,7 @@ struct _virHypervisorDriver {
     virDrvDomainMigrateStartPostCopy domainMigrateStartPostCopy;
     virDrvDomainGetGuestVcpus domainGetGuestVcpus;
     virDrvDomainSetGuestVcpus domainSetGuestVcpus;
+    virDrvDomainSetVcpu domainSetVcpu;
 };
 
 

src/libvirt-domain.c

@@ -11749,3 +11749,51 @@ virDomainSetGuestVcpus(virDomainPtr domain,
     virDispatchError(domain->conn);
     return -1;
 }
+
+
+/**
+ * virDomainSetVcpu:
+ * @domain: pointer to domain object
+ * @vcpumap: text representation of a bitmap of vcpus to set
+ * @state: 0 to disable/1 to enable cpus described by @vcpumap
+ * @flags: bitwise-OR of virDomainModificationImpact
+ *
+ * Enables/disables individual vcpus described by @vcpumap in the hypervisor.
+ *
+ * Various hypervisor implementations may limit to operate on just 1
+ * hotpluggable entity (which may contain multiple vCPUs on certain platforms).
+ *
+ * Note that OSes and hypervisors may require vCPU 0 to stay online.
+ *
+ * Returns 0 on success, -1 on error.
+ */
+int
+virDomainSetVcpu(virDomainPtr domain,
+                 const char *vcpumap,
+                 int state,
+                 unsigned int flags)
+{
+    VIR_DOMAIN_DEBUG(domain, "vcpumap='%s' state=%i flags=%x",
+                     NULLSTR(vcpumap), state, flags);
+
+    virResetLastError();
+
+    virCheckDomainReturn(domain, -1);
+    virCheckReadOnlyGoto(domain->conn->flags, error);
+
+    virCheckNonNullArgGoto(vcpumap, error);
+
+    if (domain->conn->driver->domainSetVcpu) {
+        int ret;
+        ret = domain->conn->driver->domainSetVcpu(domain, vcpumap, state, flags);
+        if (ret < 0)
+            goto error;
+        return ret;
+    }
+
+    virReportUnsupportedError();
+
+ error:
+    virDispatchError(domain->conn);
+    return -1;
+}

src/libvirt_public.syms

@@ -753,4 +753,9 @@ LIBVIRT_3.0.0 {
         virConnectSecretEventDeregisterAny;
 } LIBVIRT_2.2.0;
 
+LIBVIRT_3.1.0 {
+    global:
+        virDomainSetVcpu;
+} LIBVIRT_3.0.0;
+
 # .... define new API here using predicted next version number ....

src/remote/remote_driver.c

@@ -8402,6 +8402,7 @@ static virHypervisorDriver hypervisor_driver = {
     .domainMigrateStartPostCopy = remoteDomainMigrateStartPostCopy, /* 1.3.3 */
     .domainGetGuestVcpus = remoteDomainGetGuestVcpus, /* 2.0.0 */
     .domainSetGuestVcpus = remoteDomainSetGuestVcpus, /* 2.0.0 */
+    .domainSetVcpu = remoteDomainSetVcpu, /* 3.1.0 */
 };
 
 static virNetworkDriver network_driver = {

src/remote/remote_protocol.x

@@ -3353,6 +3353,13 @@ struct remote_domain_set_guest_vcpus_args {
     unsigned int flags;
 };
 
+struct remote_domain_set_vcpu_args {
+    remote_nonnull_domain dom;
+    remote_nonnull_string cpumap;
+    int state;
+    unsigned int flags;
+};
+
 
 struct remote_domain_event_callback_metadata_change_msg {
     int callbackID;
@@ -6018,6 +6025,13 @@ enum remote_procedure {
      * @generate: both
      * @acl: none
      */
-    REMOTE_PROC_SECRET_EVENT_VALUE_CHANGED = 383
+    REMOTE_PROC_SECRET_EVENT_VALUE_CHANGED = 383,
 
+    /**
+     * @generate: both
+     * @acl: domain:write
+     * @acl: domain:save:!VIR_DOMAIN_AFFECT_CONFIG|VIR_DOMAIN_AFFECT_LIVE
+     * @acl: domain:save:VIR_DOMAIN_AFFECT_CONFIG
+     */
+    REMOTE_PROC_DOMAIN_SET_VCPU = 384
 };

src/remote_protocol-structs

@@ -2800,6 +2800,12 @@ struct remote_domain_set_guest_vcpus_args {
         int                        state;
         u_int                      flags;
 };
+struct remote_domain_set_vcpu_args {
+        remote_nonnull_domain      dom;
+        remote_nonnull_string      cpumap;
+        int                        state;
+        u_int                      flags;
+};
 struct remote_domain_event_callback_metadata_change_msg {
         int                        callbackID;
         remote_nonnull_domain      dom;
@@ -3210,4 +3216,5 @@ enum remote_procedure {
         REMOTE_PROC_CONNECT_SECRET_EVENT_DEREGISTER_ANY = 381,
         REMOTE_PROC_SECRET_EVENT_LIFECYCLE = 382,
         REMOTE_PROC_SECRET_EVENT_VALUE_CHANGED = 383,
+        REMOTE_PROC_DOMAIN_SET_VCPU = 384,
 };