qemu: Unplug devices that disappeared when libvirtd was down

In case libvirtd is asked to unplug a device but the device is actually
unplugged later when libvirtd is not running, we need to detect that and
remove such device when libvirtd starts again and reconnects to running
domains.

src/qemu/qemu_domain.c

@@ -339,6 +339,16 @@ qemuDomainObjPrivateXMLFormat(virBufferPtr buf, void *data)
     if (priv->fakeReboot)
         virBufferAddLit(buf, "  <fakereboot/>\n");
 
+    if (priv->qemuDevices && *priv->qemuDevices) {
+        char **tmp = priv->qemuDevices;
+        virBufferAddLit(buf, "  <devices>\n");
+        while (*tmp) {
+            virBufferAsprintf(buf, "    <device alias='%s'/>\n", *tmp);
+            tmp++;
+        }
+        virBufferAddLit(buf, "  </devices>\n");
+    }
+
     return 0;
 }
 
@@ -479,12 +489,35 @@ qemuDomainObjPrivateXMLParse(xmlXPathContextPtr ctxt, void *data)
 
     priv->fakeReboot = virXPathBoolean("boolean(./fakereboot)", ctxt) == 1;
 
+    if ((n = virXPathNodeSet("./devices/device", ctxt, &nodes)) < 0) {
+        virReportError(VIR_ERR_INTERNAL_ERROR, "%s",
+                       _("failed to parse qemu device list"));
+        goto error;
+    }
+    if (n > 0) {
+        /* NULL-terminated list */
+        if (VIR_ALLOC_N(priv->qemuDevices, n + 1) < 0)
+            goto error;
+
+        for (i = 0; i < n; i++) {
+            priv->qemuDevices[i] = virXMLPropString(nodes[i], "alias");
+            if (!priv->qemuDevices[i]) {
+                virReportError(VIR_ERR_INTERNAL_ERROR, "%s",
+                               _("failed to parse qemu device list"));
+                goto error;
+            }
+        }
+    }
+    VIR_FREE(nodes);
+
     return 0;
 
 error:
     virDomainChrSourceDefFree(priv->monConfig);
     priv->monConfig = NULL;
     VIR_FREE(nodes);
+    virStringFreeList(priv->qemuDevices);
+    priv->qemuDevices = NULL;
     virObjectUnref(qemuCaps);
     return -1;
 }
@@ -2214,3 +2247,26 @@ qemuDomainMemoryLimit(virDomainDefPtr def)
 
     return mem;
 }
+
+
+int
+qemuDomainUpdateDeviceList(virQEMUDriverPtr driver,
+                           virDomainObjPtr vm)
+{
+    qemuDomainObjPrivatePtr priv = vm->privateData;
+    char **aliases;
+
+    if (!virQEMUCapsGet(priv->qemuCaps, QEMU_CAPS_DEVICE_DEL_EVENT))
+        return 0;
+
+    qemuDomainObjEnterMonitor(driver, vm);
+    if (qemuMonitorGetDeviceAliases(priv->mon, &aliases) < 0) {
+        qemuDomainObjExitMonitor(driver, vm);
+        return -1;
+    }
+    qemuDomainObjExitMonitor(driver, vm);
+
+    virStringFreeList(priv->qemuDevices);
+    priv->qemuDevices = aliases;
+    return 0;
+}

src/qemu/qemu_domain.h

@@ -171,6 +171,7 @@ struct _qemuDomainObjPrivate {
 
     virCond unplugFinished; /* signals that unpluggingDevice was unplugged */
     const char *unpluggingDevice; /* alias of the device that is being unplugged */
+    char **qemuDevices; /* NULL-terminated list of devices aliases known to QEMU */
 };
 
 typedef enum {
@@ -363,4 +364,7 @@ extern virDomainDefParserConfig virQEMUDriverDomainDefParserConfig;
 
 unsigned long long qemuDomainMemoryLimit(virDomainDefPtr def);
 
+int qemuDomainUpdateDeviceList(virQEMUDriverPtr driver,
+                               virDomainObjPtr vm);
+
 #endif /* __QEMU_DOMAIN_H__ */

src/qemu/qemu_driver.c

@@ -6494,6 +6494,9 @@ qemuDomainAttachDeviceLive(virDomainObjPtr vm,
         break;
     }
 
+    if (ret == 0)
+        qemuDomainUpdateDeviceList(driver, vm);
+
     return ret;
 }
 
@@ -6603,6 +6606,9 @@ qemuDomainDetachDeviceLive(virDomainObjPtr vm,
         break;
     }
 
+    if (ret == 0)
+        qemuDomainUpdateDeviceList(driver, vm);
+
     return ret;
 }
 

src/qemu/qemu_process.c

@@ -2969,6 +2969,39 @@ qemuProcessRecoverJob(virQEMUDriverPtr driver,
     return 0;
 }
 
+static int
+qemuProcessUpdateDevices(virQEMUDriverPtr driver,
+                         virDomainObjPtr vm)
+{
+    qemuDomainObjPrivatePtr priv = vm->privateData;
+    virDomainDeviceDef dev;
+    char **old;
+    char **tmp;
+    int ret = -1;
+
+    if (!virQEMUCapsGet(priv->qemuCaps, QEMU_CAPS_DEVICE_DEL_EVENT))
+        return 0;
+
+    old = priv->qemuDevices;
+    priv->qemuDevices = NULL;
+    if (qemuDomainUpdateDeviceList(driver, vm) < 0)
+        goto cleanup;
+
+    if ((tmp = old)) {
+        while (*tmp) {
+            if (!virStringArrayHasString(priv->qemuDevices, *tmp) &&
+                virDomainDefFindDevice(vm->def, *tmp, &dev, false) == 0)
+                qemuDomainRemoveDevice(driver, vm, &dev);
+            tmp++;
+        }
+    }
+    ret = 0;
+
+cleanup:
+    virStringFreeList(old);
+    return ret;
+}
+
 struct qemuProcessReconnectData {
     virConnectPtr conn;
     virQEMUDriverPtr driver;
@@ -3105,6 +3138,9 @@ qemuProcessReconnect(void *opaque)
     if (qemuProcessRecoverJob(driver, obj, conn, &oldjob) < 0)
         goto error;
 
+    if (qemuProcessUpdateDevices(driver, obj) < 0)
+        goto error;
+
     /* update domain state XML with possibly updated state in virDomainObj */
     if (virDomainSaveStatus(driver->xmlopt, cfg->stateDir, obj) < 0)
         goto error;
@@ -3905,6 +3941,10 @@ int qemuProcessStart(virConnectPtr conn,
 
     qemuDomainObjExitMonitor(driver, vm);
 
+    VIR_DEBUG("Fetching list of active devices");
+    if (qemuDomainUpdateDeviceList(driver, vm) < 0)
+        goto cleanup;
+
     /* Technically, qemuProcessStart can be called from inside
      * QEMU_ASYNC_JOB_MIGRATION_IN, but we are okay treating this like
      * a sync job since no other job can call into the domain until
@@ -4166,6 +4206,9 @@ void qemuProcessStop(virQEMUDriverPtr driver,
         VIR_FREE(vm->def->seclabels[i]->imagelabel);
     }
 
+    virStringFreeList(priv->qemuDevices);
+    priv->qemuDevices = NULL;
+
     virDomainDefClearDeviceAliases(vm->def);
     if (!priv->persistentAddrs) {
         virDomainDefClearPCIAddresses(vm->def);