ch: Add CPU hotplug support code

Add functions for managing CPU hotplug. This is intended to be used by
the driver to fully enable CPU hotplug support.

Author: bryteise

src/ch/ch_hotplug.c

@@ -0,0 +1,137 @@
+/*
+ * ch_hostdev.h: Cloud Hypervisor hotplug support
+ *
+ * Copyright Intel Corp. 2020
+ *
+ * This library is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation; either
+ * version 2.1 of the License, or (at your option) any later version.
+ *
+ * This library is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with this library.  If not, see
+ * <http://www.gnu.org/licenses/>.
+ */
+
+#include "ch_cgroup.h"
+#include "ch_domain.h"
+#include "ch_hotplug.h"
+#include "ch_monitor.h"
+#include "ch_process.h"
+#include "domain_audit.h"
+#include "virerror.h"
+#include "virlog.h"
+
+#define VIR_FROM_THIS VIR_FROM_CH
+
+VIR_LOG_INIT("ch.ch_hotplug");
+
+/**
+ * virCHDomainSelectHotplugVcpuEntities:
+ *
+ * @def: domain definition
+ * @nvcpus: target vcpu count
+ *
+ * Validate vcpu entities will be able to be enabled/disabled.
+ *
+ * Returns the true if the nvcpus can be set, false if not.
+ */
+static bool
+virCHDomainValidateHotplugVcpuEntities(virDomainDefPtr def,
+                                       unsigned int nvcpus)
+{
+    unsigned int maxvcpus = virDomainDefGetVcpusMax(def);
+
+    if (nvcpus < 1 || nvcpus > maxvcpus) {
+        virReportError(VIR_ERR_INVALID_ARG,
+                       _("requested vcpus is greater than max allowable"
+                         " vcpus for the live domain: %u > %u"),
+                       nvcpus, maxvcpus);
+        return false;
+    }
+
+    return true;
+}
+
+static int
+virCHDomainHotplugSetVcpus(virDomainObjPtr vm,
+                           unsigned int nvcpus)
+{
+    unsigned int maxvcpus = virDomainDefGetVcpusMax(vm->def);
+    int oldvcpus = virDomainDefGetVcpus(vm->def);
+    virCHDomainObjPrivatePtr priv = vm->privateData;
+    virCHMonitorPtr mon = priv->monitor;
+    int ret = -1;
+
+    VIR_DEBUG("Setting cpu count to %d", nvcpus);
+    ret = virCHMonitorResizeCPU(mon, nvcpus);
+
+    virDomainAuditVcpu(vm, oldvcpus, nvcpus, "update", ret == 0);
+
+    if (ret < 0)
+        goto error;
+
+    /* Set cpu status for validation (after the monitor sees the change) */
+    for (int i = 0; i < nvcpus; i++) {
+        virDomainVcpuDefPtr vcpuinfo = virDomainDefGetVcpu(vm->def, i);
+        vcpuinfo->online = true;
+    }
+    for (int i = nvcpus; i < maxvcpus; i++) {
+        virDomainVcpuDefPtr vcpuinfo = virDomainDefGetVcpu(vm->def, i);
+        vcpuinfo->online = false;
+    }
+
+    ret = 0;
+
+ error:
+    return ret;
+
+}
+
+static int
+virCHDomainSetVcpusLive(virDomainObjPtr vm,
+                        unsigned int nvcpus)
+{
+    virCHDomainObjPrivatePtr priv = vm->privateData;
+    chCgroupEmulatorAllNodesDataPtr emulatorCgroup = NULL;
+    int ret = -1;
+
+    if (chCgroupEmulatorAllNodesAllow(priv->cgroup, &emulatorCgroup) < 0)
+        goto cleanup;
+
+    if (virCHDomainHotplugSetVcpus(vm, nvcpus) < 0)
+        goto cleanup;
+
+    ret = 0;
+
+ cleanup:
+    chCgroupEmulatorAllNodesRestore(emulatorCgroup);
+
+    return ret;
+}
+
+int
+virCHDomainSetVcpusInternal(virDomainObjPtr vm,
+                            virDomainDefPtr def,
+                            unsigned int nvcpus)
+{
+    int ret = -1;
+
+    if (def) {
+        if (!virCHDomainValidateHotplugVcpuEntities(def, nvcpus))
+            goto error;
+
+        if (virCHDomainSetVcpusLive(vm, nvcpus) < 0)
+            goto error;
+    }
+
+    ret = 0;
+
+ error:
+    return ret;
+}

src/ch/ch_hotplug.h

@@ -0,0 +1,30 @@
+/*
+ * ch_hostdev.h: Cloud Hypervisor hotplug support
+ *
+ * Copyright Intel Corp. 2020
+ *
+ * This library is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation; either
+ * version 2.1 of the License, or (at your option) any later version.
+ *
+ * This library is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with this library.  If not, see
+ * <http://www.gnu.org/licenses/>.
+ */
+
+#pragma once
+
+#include "ch_conf.h"
+#include "domain_conf.h"
+
+
+int
+virCHDomainSetVcpusInternal(virDomainObjPtr vm,
+                            virDomainDefPtr def,
+                            unsigned int nvcpus);

src/ch/meson.build

@@ -9,6 +9,8 @@ ch_driver_sources = [
   'ch_driver.h',
   'ch_hostdev.c',
   'ch_hostdev.h',
+  'ch_hotplug.c',
+  'ch_hotplug.h',
   'ch_monitor.c',
   'ch_monitor.h',
   'ch_process.c',