qemu: Add support to Add/Delete IOThreads

Add qemuDomainAddIOThread and qemuDomainDelIOThread in order to add or
remove an IOThread to/from the host either for live or config optoins

The implementation for the 'live' option will use the iothreadpids list
in order to make decision, while the 'config' option will use the
iothreadids list.  Additionally, for deletion each may have to adjust
the iothreadpin list.

IOThreads are implemented by qmp objects, the code makes use of the existing
qemuMonitorAddObject or qemuMonitorDelObject APIs.
Signed-off-by: NJohn Ferlan <jferlan@redhat.com>

src/conf/domain_audit.c

@@ -790,6 +790,15 @@ virDomainAuditVcpu(virDomainObjPtr vm,
     return virDomainAuditResource(vm, "vcpu", oldvcpu, newvcpu, reason, success);
 }
 
+void
+virDomainAuditIOThread(virDomainObjPtr vm,
+                       unsigned int oldiothread, unsigned int newiothread,
+                       const char *reason, bool success)
+{
+    return virDomainAuditResource(vm, "iothread", oldiothread, newiothread,
+                                  reason, success);
+}
+
 static void
 virDomainAuditLifecycle(virDomainObjPtr vm, const char *op,
                         const char *reason, bool success)

src/conf/domain_audit.h

@@ -102,6 +102,12 @@ void virDomainAuditVcpu(virDomainObjPtr vm,
                         const char *reason,
                         bool success)
     ATTRIBUTE_NONNULL(1) ATTRIBUTE_NONNULL(4);
+void virDomainAuditIOThread(virDomainObjPtr vm,
+                            unsigned int oldiothread,
+                            unsigned int newiothread,
+                            const char *reason,
+                            bool success)
+    ATTRIBUTE_NONNULL(1) ATTRIBUTE_NONNULL(4);
 void virDomainAuditSecurityLabel(virDomainObjPtr vm,
                                  bool success)
     ATTRIBUTE_NONNULL(1);

src/libvirt_private.syms

@@ -127,6 +127,7 @@ virDomainAuditDisk;
 virDomainAuditFS;
 virDomainAuditHostdev;
 virDomainAuditInit;
+virDomainAuditIOThread;
 virDomainAuditMemory;
 virDomainAuditNet;
 virDomainAuditNetDevice;

src/qemu/qemu_driver.c

@@ -6230,6 +6230,370 @@ qemuDomainPinIOThread(virDomainPtr dom,
     return ret;
 }
 
+static int
+qemuDomainHotplugAddIOThread(virQEMUDriverPtr driver,
+                             virDomainObjPtr vm,
+                             unsigned int iothread_id)
+{
+    qemuDomainObjPrivatePtr priv = vm->privateData;
+    char *alias = NULL;
+    size_t idx;
+    int rc = -1;
+    int ret = -1;
+    unsigned int orig_niothreads = vm->def->iothreads;
+    unsigned int exp_niothreads = vm->def->iothreads;
+    int new_niothreads = 0;
+    qemuMonitorIOThreadInfoPtr *new_iothreads = NULL;
+    virCgroupPtr cgroup_iothread = NULL;
+    char *mem_mask = NULL;
+    virDomainIOThreadIDDefPtr iothrid;
+    virBitmapPtr cpumask;
+
+    if (virDomainIOThreadIDFind(vm->def, iothread_id)) {
+        virReportError(VIR_ERR_INVALID_ARG,
+                       _("an IOThread is already using iothread_id '%u'"),
+                       iothread_id);
+        goto cleanup;
+    }
+
+    if (virAsprintf(&alias, "iothread%u", iothread_id) < 0)
+        return -1;
+
+    qemuDomainObjEnterMonitor(driver, vm);
+
+    rc = qemuMonitorAddObject(priv->mon, "iothread", alias, NULL);
+    exp_niothreads++;
+    if (rc < 0)
+        goto exit_monitor;
+
+    /* After hotplugging the IOThreads we need to re-detect the
+     * IOThreads thread_id's, adjust the cgroups, thread affinity,
+     * and add the thread_id to the vm->def->iothreadids list.
+     */
+    if ((new_niothreads = qemuMonitorGetIOThreads(priv->mon,
+                                                  &new_iothreads)) < 0)
+        goto exit_monitor;
+
+    if (qemuDomainObjExitMonitor(driver, vm) < 0)
+        goto cleanup;
+
+    if (new_niothreads != exp_niothreads) {
+        virReportError(VIR_ERR_INTERNAL_ERROR,
+                       _("got wrong number of IOThread ids from QEMU monitor. "
+                         "got %d, wanted %d"),
+                       new_niothreads, exp_niothreads);
+        vm->def->iothreads = new_niothreads;
+        goto cleanup;
+    }
+    vm->def->iothreads = exp_niothreads;
+
+    if (virDomainNumatuneGetMode(vm->def->numa, -1) ==
+        VIR_DOMAIN_NUMATUNE_MEM_STRICT &&
+        virDomainNumatuneMaybeFormatNodeset(vm->def->numa,
+                                            priv->autoNodeset,
+                                            &mem_mask, -1) < 0)
+        goto cleanup;
+
+
+    /*
+     * If we've successfully added an IOThread, find out where we added it
+     * in the QEMU IOThread list, so we can add it to our iothreadids list
+     */
+    for (idx = 0; idx < new_niothreads; idx++) {
+        if (STREQ(new_iothreads[idx]->name, alias))
+            break;
+    }
+
+    if (idx == new_niothreads) {
+        virReportError(VIR_ERR_INTERNAL_ERROR,
+                       _("cannot find new IOThread '%u' in QEMU monitor."),
+                       iothread_id);
+        goto cleanup;
+    }
+
+    if (!(iothrid = virDomainIOThreadIDAdd(vm->def, iothread_id)))
+        goto cleanup;
+
+    iothrid->thread_id = new_iothreads[idx]->thread_id;
+
+    /* Add IOThread to cgroup if present */
+    if (priv->cgroup) {
+        cgroup_iothread =
+            qemuDomainAddCgroupForThread(priv->cgroup,
+                                         VIR_CGROUP_THREAD_IOTHREAD,
+                                         iothread_id, mem_mask,
+                                         iothrid->thread_id);
+        if (!cgroup_iothread)
+            goto cleanup;
+    }
+
+    if (vm->def->placement_mode == VIR_DOMAIN_CPU_PLACEMENT_MODE_AUTO)
+        cpumask = priv->autoCpuset;
+    else
+        cpumask = vm->def->cpumask;
+
+    if (cpumask) {
+        if (qemuDomainHotplugPinThread(cpumask, iothread_id,
+                                       iothrid->thread_id, cgroup_iothread) < 0)
+            goto cleanup;
+    }
+
+    ret = 0;
+
+ cleanup:
+    if (new_iothreads) {
+        for (idx = 0; idx < new_niothreads; idx++)
+            qemuMonitorIOThreadInfoFree(new_iothreads[idx]);
+        VIR_FREE(new_iothreads);
+    }
+    VIR_FREE(mem_mask);
+    virDomainAuditIOThread(vm, orig_niothreads, new_niothreads,
+                           "update", rc == 0);
+    virCgroupFree(&cgroup_iothread);
+    VIR_FREE(alias);
+    return ret;
+
+ exit_monitor:
+    ignore_value(qemuDomainObjExitMonitor(driver, vm));
+    goto cleanup;
+}
+
+static int
+qemuDomainHotplugDelIOThread(virQEMUDriverPtr driver,
+                             virDomainObjPtr vm,
+                             unsigned int iothread_id)
+{
+    qemuDomainObjPrivatePtr priv = vm->privateData;
+    size_t idx;
+    char *alias = NULL;
+    int rc = -1;
+    int ret = -1;
+    unsigned int orig_niothreads = vm->def->iothreads;
+    unsigned int exp_niothreads = vm->def->iothreads;
+    int new_niothreads = 0;
+    qemuMonitorIOThreadInfoPtr *new_iothreads = NULL;
+
+    /* Normally would use virDomainIOThreadIDFind, but we need the index
+     * from whence to delete for later...
+     */
+    for (idx = 0; idx < vm->def->niothreadids; idx++) {
+        if (iothread_id == vm->def->iothreadids[idx]->iothread_id)
+            break;
+    }
+
+    if (idx == vm->def->niothreadids) {
+        virReportError(VIR_ERR_INVALID_ARG,
+                       _("cannot find IOThread '%u' in iothreadids list"),
+                       iothread_id);
+        return -1;
+    }
+
+    if (virAsprintf(&alias, "iothread%u", iothread_id) < 0)
+        return -1;
+
+    qemuDomainObjEnterMonitor(driver, vm);
+
+    rc = qemuMonitorDelObject(priv->mon, alias);
+    exp_niothreads--;
+    if (rc < 0)
+        goto exit_monitor;
+
+    if ((new_niothreads = qemuMonitorGetIOThreads(priv->mon,
+                                                  &new_iothreads)) < 0)
+        goto exit_monitor;
+
+    if (qemuDomainObjExitMonitor(driver, vm) < 0)
+        goto cleanup;
+
+    if (new_niothreads != exp_niothreads) {
+        virReportError(VIR_ERR_INTERNAL_ERROR,
+                       _("got wrong number of IOThread ids from QEMU monitor. "
+                         "got %d, wanted %d"),
+                       new_niothreads, exp_niothreads);
+        vm->def->iothreads = new_niothreads;
+        goto cleanup;
+    }
+    vm->def->iothreads = exp_niothreads;
+
+    virDomainIOThreadIDDel(vm->def, iothread_id);
+
+    virDomainIOThreadSchedDelId(vm->def, iothread_id);
+
+    if (qemuDomainDelCgroupForThread(priv->cgroup,
+                                     VIR_CGROUP_THREAD_IOTHREAD,
+                                     iothread_id) < 0)
+        goto cleanup;
+
+    ret = 0;
+
+ cleanup:
+    if (new_iothreads) {
+        for (idx = 0; idx < new_niothreads; idx++)
+            qemuMonitorIOThreadInfoFree(new_iothreads[idx]);
+        VIR_FREE(new_iothreads);
+    }
+    virDomainAuditIOThread(vm, orig_niothreads, new_niothreads,
+                           "update", rc == 0);
+    VIR_FREE(alias);
+    return ret;
+
+ exit_monitor:
+    ignore_value(qemuDomainObjExitMonitor(driver, vm));
+    goto cleanup;
+}
+
+static int
+qemuDomainChgIOThread(virQEMUDriverPtr driver,
+                      virDomainObjPtr vm,
+                      unsigned int iothread_id,
+                      bool add,
+                      unsigned int flags)
+{
+    virQEMUDriverConfigPtr cfg = NULL;
+    virCapsPtr caps = NULL;
+    qemuDomainObjPrivatePtr priv;
+    virDomainDefPtr persistentDef;
+    int ret = -1;
+
+    cfg = virQEMUDriverGetConfig(driver);
+
+    if (!(caps = virQEMUDriverGetCapabilities(driver, false)))
+        goto cleanup;
+
+    priv = vm->privateData;
+
+    if (qemuDomainObjBeginJob(driver, vm, QEMU_JOB_MODIFY) < 0)
+        goto cleanup;
+
+    if (virDomainLiveConfigHelperMethod(caps, driver->xmlopt, vm, &flags,
+                                        &persistentDef) < 0)
+        goto endjob;
+
+    if (flags & VIR_DOMAIN_AFFECT_LIVE) {
+        if (!virDomainObjIsActive(vm)) {
+            virReportError(VIR_ERR_OPERATION_INVALID, "%s",
+                           _("cannot change IOThreads for an inactive domain"));
+            goto endjob;
+        }
+
+        if (!virQEMUCapsGet(priv->qemuCaps, QEMU_CAPS_OBJECT_IOTHREAD)) {
+            virReportError(VIR_ERR_CONFIG_UNSUPPORTED, "%s",
+                           _("IOThreads not supported with this binary"));
+            goto endjob;
+        }
+
+        if (add) {
+            if (qemuDomainHotplugAddIOThread(driver, vm, iothread_id) < 0)
+                goto endjob;
+        } else {
+            if (qemuDomainHotplugDelIOThread(driver, vm, iothread_id) < 0)
+                goto endjob;
+        }
+
+        if (virDomainSaveStatus(driver->xmlopt, cfg->stateDir, vm) < 0)
+            goto endjob;
+    }
+
+    if (flags & VIR_DOMAIN_AFFECT_CONFIG) {
+        if (add) {
+            if (!virDomainIOThreadIDAdd(persistentDef, iothread_id))
+                goto endjob;
+
+            persistentDef->iothreads++;
+        } else {
+            virDomainIOThreadIDDefPtr iothrid;
+            if (!(iothrid = virDomainIOThreadIDFind(persistentDef,
+                                                    iothread_id))) {
+                virReportError(VIR_ERR_INVALID_ARG,
+                               _("cannot find IOThread '%u' in persistent "
+                                 "iothreadids"),
+                               iothread_id);
+                goto cleanup;
+            }
+
+            virDomainIOThreadIDDel(persistentDef, iothread_id);
+            virDomainIOThreadSchedDelId(persistentDef, iothread_id);
+            persistentDef->iothreads--;
+        }
+
+        if (virDomainSaveConfig(cfg->configDir, persistentDef) < 0)
+            goto endjob;
+    }
+
+    ret = 0;
+
+ endjob:
+    qemuDomainObjEndJob(driver, vm);
+
+ cleanup:
+    virObjectUnref(caps);
+    virObjectUnref(cfg);
+    return ret;
+}
+
+static int
+qemuDomainAddIOThread(virDomainPtr dom,
+                      unsigned int iothread_id,
+                      unsigned int flags)
+{
+    virQEMUDriverPtr driver = dom->conn->privateData;
+    virDomainObjPtr vm = NULL;
+    int ret = -1;
+
+    virCheckFlags(VIR_DOMAIN_AFFECT_LIVE |
+                  VIR_DOMAIN_AFFECT_CONFIG, -1);
+
+    if (!(vm = qemuDomObjFromDomain(dom)))
+        goto cleanup;
+
+    if (virDomainAddIOThreadEnsureACL(dom->conn, vm->def, flags) < 0)
+        goto cleanup;
+
+    ret = qemuDomainChgIOThread(driver, vm, iothread_id, true, flags);
+
+ cleanup:
+    virDomainObjEndAPI(&vm);
+    return ret;
+}
+
+
+static int
+qemuDomainDelIOThread(virDomainPtr dom,
+                      unsigned int iothread_id,
+                      unsigned int flags)
+{
+    virQEMUDriverPtr driver = dom->conn->privateData;
+    virDomainObjPtr vm = NULL;
+    int ret = -1;
+    size_t i;
+
+    virCheckFlags(VIR_DOMAIN_AFFECT_LIVE |
+                  VIR_DOMAIN_AFFECT_CONFIG, -1);
+
+    if (!(vm = qemuDomObjFromDomain(dom)))
+        goto cleanup;
+
+    if (virDomainDelIOThreadEnsureACL(dom->conn, vm->def, flags) < 0)
+           goto cleanup;
+
+    /* If there is a disk using the IOThread to be removed, then fail. */
+    for (i = 0; i < vm->def->ndisks; i++) {
+        if (vm->def->disks[i]->iothread == iothread_id) {
+            virReportError(VIR_ERR_INVALID_ARG,
+                           _("cannot remove IOThread %u since it "
+                             "is being used by disk '%s'"),
+                           iothread_id, vm->def->disks[i]->dst);
+            goto cleanup;
+        }
+    }
+
+    ret = qemuDomainChgIOThread(driver, vm, iothread_id, false, flags);
+
+ cleanup:
+    virDomainObjEndAPI(&vm);
+    return ret;
+}
+
 static int qemuDomainGetSecurityLabel(virDomainPtr dom, virSecurityLabelPtr seclabel)
 {
     virQEMUDriverPtr driver = dom->conn->privateData;
@@ -19967,6 +20331,8 @@ static virHypervisorDriver qemuHypervisorDriver = {
     .domainGetMaxVcpus = qemuDomainGetMaxVcpus, /* 0.4.4 */
     .domainGetIOThreadInfo = qemuDomainGetIOThreadInfo, /* 1.2.14 */
     .domainPinIOThread = qemuDomainPinIOThread, /* 1.2.14 */
+    .domainAddIOThread = qemuDomainAddIOThread, /* 1.2.15 */
+    .domainDelIOThread = qemuDomainDelIOThread, /* 1.2.15 */
     .domainGetSecurityLabel = qemuDomainGetSecurityLabel, /* 0.6.1 */
     .domainGetSecurityLabelList = qemuDomainGetSecurityLabelList, /* 0.10.0 */
     .nodeGetSecurityModel = qemuNodeGetSecurityModel, /* 0.6.1 */