[libvirt] [PATCH 4/4] Fix CDROM media change for QEMU when using -device syntax

["Daniel P. Berrange" <berrange@xxxxxxxxxx>]

Disk devices in QEMU have two parts, the guest device and the host
backend driver. Historically these two parts have had the same
"unique" name. With the switch to using -device though, they now
have separate names. Thus when changing CDROM media, for guests
using -device syntax, we need to prepend the QEMU_DRIVE_HOST_PREFIX
constant

* src/qemu/qemu_conf.c, src/qemu/qemu_conf.h: Add helper function
  qemuDeviceDriveHostAlias() for building a host backend alias
* src/qemu/qemu_driver.c: Use qemuDeviceDriveHostAlias() to determine
  the host backend alias for performing eject/change commands in the
  monitor
---
 src/qemu/qemu_conf.c   |   20 ++++++++++++++++++++
 src/qemu/qemu_conf.h   |    3 +++
 src/qemu/qemu_driver.c |   18 +++++++++++++-----
 3 files changed, 36 insertions(+), 5 deletions(-)

diff --git a/src/qemu/qemu_conf.c b/src/qemu/qemu_conf.c
index 5b5cdb0..e1cfbbb 100644
--- a/src/qemu/qemu_conf.c
+++ b/src/qemu/qemu_conf.c
@@ -1699,6 +1699,26 @@ static int qemuAssignDeviceDiskAliasLegacy(virDomainDiskDefPtr disk)
 }
 
 
+char *qemuDeviceDriveHostAlias(virDomainDiskDefPtr disk,
+                               unsigned long long qemudCmdFlags)
+{
+    char *ret;
+
+    if (qemudCmdFlags & QEMUD_CMD_FLAG_DEVICE) {
+        if (virAsprintf(&ret, "%s%s", QEMU_DRIVE_HOST_PREFIX, disk->info.alias) < 0) {
+            virReportOOMError();
+            return NULL;
+        }
+    } else {
+        if (!(ret = strdup(disk->info.alias))) {
+            virReportOOMError();
+            return NULL;
+        }
+    }
+    return ret;
+}
+
+
 /* Names used before -drive supported the id= option */
 static int qemuAssignDeviceDiskAliasFixed(virDomainDiskDefPtr disk)
 {
diff --git a/src/qemu/qemu_conf.h b/src/qemu/qemu_conf.h
index 574709e..b2820f0 100644
--- a/src/qemu/qemu_conf.h
+++ b/src/qemu/qemu_conf.h
@@ -220,6 +220,9 @@ char * qemuBuildNicStr(virDomainNetDefPtr net,
 char * qemuBuildNicDevStr(virDomainNetDefPtr net,
                           int vlan);
 
+char *qemuDeviceDriveHostAlias(virDomainDiskDefPtr disk,
+                               unsigned long long qemudCmdFlags);
+
 /* Both legacy & current support */
 char *qemuBuildDriveStr(virDomainDiskDefPtr disk,
                         int bootable,
diff --git a/src/qemu/qemu_driver.c b/src/qemu/qemu_driver.c
index df1d435..25257df 100644
--- a/src/qemu/qemu_driver.c
+++ b/src/qemu/qemu_driver.c
@@ -6567,11 +6567,13 @@ cleanup:
 
 static int qemudDomainChangeEjectableMedia(struct qemud_driver *driver,
                                            virDomainObjPtr vm,
-                                           virDomainDiskDefPtr disk)
+                                           virDomainDiskDefPtr disk,
+                                           unsigned long long qemuCmdFlags)
 {
     virDomainDiskDefPtr origdisk = NULL;
     int i;
     int ret;
+    char *driveAlias = NULL;
 
     origdisk = NULL;
     for (i = 0 ; i < vm->def->ndisks ; i++) {
@@ -6609,6 +6611,9 @@ static int qemudDomainChangeEjectableMedia(struct qemud_driver *driver,
         driver->securityDriver->domainSetSecurityImageLabel(vm, disk) < 0)
         return -1;
 
+    if (!(driveAlias = qemuDeviceDriveHostAlias(origdisk, qemuCmdFlags)))
+        goto error;
+
     qemuDomainObjPrivatePtr priv = vm->privateData;
     qemuDomainObjEnterMonitorWithDriver(driver, vm);
     if (disk->src) {
@@ -6620,10 +6625,10 @@ static int qemudDomainChangeEjectableMedia(struct qemud_driver *driver,
                 format = origdisk->driverType;
         }
         ret = qemuMonitorChangeMedia(priv->mon,
-                                     origdisk->info.alias,
+                                     driveAlias,
                                      disk->src, format);
     } else {
-        ret = qemuMonitorEjectMedia(priv->mon, origdisk->info.alias);
+        ret = qemuMonitorEjectMedia(priv->mon, driveAlias);
     }
     qemuDomainObjExitMonitorWithDriver(driver, vm);
 
@@ -6640,11 +6645,14 @@ static int qemudDomainChangeEjectableMedia(struct qemud_driver *driver,
     disk->src = NULL;
     origdisk->type = disk->type;
 
+    VIR_FREE(driveAlias);
+
     virDomainDiskDefFree(disk);
 
     return ret;
 
 error:
+    VIR_FREE(driveAlias);
     if (driver->securityDriver &&
         driver->securityDriver->domainRestoreSecurityImageLabel &&
         driver->securityDriver->domainRestoreSecurityImageLabel(vm, disk) < 0)
@@ -7443,7 +7451,7 @@ static int qemudDomainAttachDevice(virDomainPtr dom,
         switch (dev->data.disk->device) {
         case VIR_DOMAIN_DISK_DEVICE_CDROM:
         case VIR_DOMAIN_DISK_DEVICE_FLOPPY:
-            ret = qemudDomainChangeEjectableMedia(driver, vm, dev->data.disk);
+            ret = qemudDomainChangeEjectableMedia(driver, vm, dev->data.disk, qemuCmdFlags);
             if (ret == 0)
                 dev->data.disk = NULL;
             break;
@@ -7688,7 +7696,7 @@ static int qemuDomainUpdateDeviceFlags(virDomainPtr dom,
         switch (dev->data.disk->device) {
         case VIR_DOMAIN_DISK_DEVICE_CDROM:
         case VIR_DOMAIN_DISK_DEVICE_FLOPPY:
-            ret = qemudDomainChangeEjectableMedia(driver, vm, dev->data.disk);
+            ret = qemudDomainChangeEjectableMedia(driver, vm, dev->data.disk, qemuCmdFlags);
             if (ret == 0)
                 dev->data.disk = NULL;
             break;
-- 
1.6.6.1

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