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[libvirt] [PATCH] qemu: fix attach/detach of netdevs with matching mac addrs



This resolves:

   https://bugzilla.redhat.com/show_bug.cgi?id=862515

which describes inconsistencies in dealing with duplicate mac
addresses on network devices in a domain.

(at any rate, it resolves *almost* everything, and prints out an
informative error message for the one problem that isn't solved, but
has a workaround.)

A synopsis of the problems:

1) you can't do a persistent attach-interface of a device with a mac
address that matches an existing device.

2) you *can* do a live attach-interface of such a device.

3) you *can* directly edit a domain and put in two devices with
matching mac addresses.

4) When running virsh detach-device (live or config), only MAC address
is checked when matching the device to remove, so the first device
with the desired mac address will be removed. This isn't always the
one that's wanted.

5) when running virsh detach-interface (live or config), the only two
items that can be specified to match against are mac address and model
type (virtio, etc) - if multiple netdevs match both of those
attributes, it again just finds the first one added and assumes that
is the only match.

Since it is completely valid to have multiple network devices with the
same MAC address (although it can cause problems in many cases, there
*are* valid use cases), what is needed is:

1) remove the restriction that prohibits doing a persistent add of a
netdev with a duplicate mac address.

2) enhance the backend of virDomainDetachDeviceFlags to check for
something that *is* guaranteed unique (but still work with just mac
address, as long as it yields only a single results.

This patch does three things:

1) removes the check for duplicate mac address during a persistent
netdev attach.

2) unifies the searching for both live and config detach of netdevices
in the subordinate functions of qemuDomainModifyDeviceFlags() to use the
new function virDomainNetFindIdx (which matches mac address and PCI
address if available, checking for duplicates if only mac address was
specified). This function returns -2 if multiple matches are found,
allowing the callers to print out an appropriate message.

Steps 1 & 2 are enough to fully fix the problem when using virsh
attach-device and detach-device (which require an XML description of
the device rather than a bunch of commandline args)

3) modifies the virsh detach-interface command to check for multiple
matches of mac address and show an error message suggesting use of the
detach-device command in cases where there are multiple matching mac
addresses.

Later we should decide how we want to input a PCI address on the virsh
commandline, and enhance detach-interface to take a --address option,
eliminating the need to use detach-device

* src/conf/domain_conf.c
* src/conf/domain_conf.h
* src/libvirt_private.syms
  * added new virDomainNetFindIdx function
  * removed now unused virDomainNetIndexByMac and
    virDomainNetRemoveByMac

* src/qemu/qemu_driver.c
  * remove check for duplicate max from qemuDomainAttachDeviceConfig
  * use virDomainNetFindIdx/virDomainNetRemove instead
    of virDomainNetRemoveByMac in qemuDomainDetachDeviceConfig
  * use virDomainNetFindIdx instead of virDomainIndexByMac
    in qemuDomainUpdateDeviceConfig

* src/qemu/qemu_hotplug.c
  * use virDomainNetFindIdx instead of a homespun loop in
    qemuDomainDetachNetDevice.

* tools/virsh-domain.c: modified detach-interface command as described
    above
---
 src/conf/domain_conf.c   | 58 ++++++++++++++++++++++++++++++++++--------------
 src/conf/domain_conf.h   | 11 +++------
 src/libvirt_private.syms |  3 +--
 src/qemu/qemu_driver.c   | 49 ++++++++++++++++++++++------------------
 src/qemu/qemu_hotplug.c  | 28 +++++++++++------------
 tools/virsh-domain.c     | 26 ++++++++++++++++------
 6 files changed, 104 insertions(+), 71 deletions(-)

diff --git a/src/conf/domain_conf.c b/src/conf/domain_conf.c
index 0933c08..51a3b36 100644
--- a/src/conf/domain_conf.c
+++ b/src/conf/domain_conf.c
@@ -7993,14 +7993,49 @@ int virDomainNetInsert(virDomainDefPtr def, virDomainNetDefPtr net)
     return 0;
 }
 
-int virDomainNetIndexByMac(virDomainDefPtr def, const virMacAddrPtr mac)
+/* virDomainNetFindIdx: search according to mac address and guest side
+ *                      PCI address (if specified)
+ *
+ * Return: index of match if unique match found
+ *         -1 if not found
+ *         -2 if multiple matches
+ */
+int
+virDomainNetFindIdx(virDomainDefPtr def, virDomainNetDefPtr net)
 {
-    int i;
+    int ii, matchidx = -1;
+    bool PCIAddrSpecified = virDomainDeviceAddressIsValid(&net->info,
+                                                          VIR_DOMAIN_DEVICE_ADDRESS_TYPE_PCI);
 
-    for (i = 0; i < def->nnets; i++)
-        if (!virMacAddrCmp(&def->nets[i]->mac, mac))
-            return i;
-    return -1;
+    for (ii = 0 ; ii < def->nnets ; ii++) {
+        if (virMacAddrCmp(&def->nets[ii]->mac, &net->mac))
+            continue;
+
+        if ((matchidx >= 0) && !PCIAddrSpecified) {
+            /* there were multiple matches on mac address, and no
+             * qualifying guest-side PCI address was given, so we must
+             * fail (NB: a USB address isn't adequate, since it may
+             * specify only vendor and product ID, and there may be
+             * multiples of those.
+             */
+            matchidx = -2; /* indicates "multiple matches" to caller */
+            break;
+        }
+        if (PCIAddrSpecified) {
+            if (virDevicePCIAddressEqual(&def->nets[ii]->info.addr.pci,
+                                         &net->info.addr.pci)) {
+                /* exit early if the pci address was specified and
+                 * it matches, as this guarantees no duplicates.
+                 */
+                matchidx = ii;
+                break;
+            }
+        } else {
+            /* no PCI address given, so there may be multiple matches */
+            matchidx = ii;
+        }
+    }
+    return matchidx;
 }
 
 virDomainNetDefPtr
@@ -8038,17 +8073,6 @@ virDomainNetRemove(virDomainDefPtr def, size_t i)
     return net;
 }
 
-virDomainNetDefPtr
-virDomainNetRemoveByMac(virDomainDefPtr def, const virMacAddrPtr mac)
-{
-    int i = virDomainNetIndexByMac(def, mac);
-
-    if (i < 0)
-        return NULL;
-    return virDomainNetRemove(def, i);
-}
-
-
 int virDomainControllerInsert(virDomainDefPtr def,
                               virDomainControllerDefPtr controller)
 {
diff --git a/src/conf/domain_conf.h b/src/conf/domain_conf.h
index 4151bc2..4c84cb5 100644
--- a/src/conf/domain_conf.h
+++ b/src/conf/domain_conf.h
@@ -2009,12 +2009,10 @@ virDomainDiskRemove(virDomainDefPtr def, size_t i);
 virDomainDiskDefPtr
 virDomainDiskRemoveByName(virDomainDefPtr def, const char *name);
 
-int virDomainNetIndexByMac(virDomainDefPtr def, const virMacAddrPtr mac);
+int virDomainNetFindIdx(virDomainDefPtr def, virDomainNetDefPtr net);
+virDomainNetDefPtr virDomainNetFind(virDomainDefPtr def, const char *device);
 int virDomainNetInsert(virDomainDefPtr def, virDomainNetDefPtr net);
-virDomainNetDefPtr
-virDomainNetRemove(virDomainDefPtr def, size_t i);
-virDomainNetDefPtr
-virDomainNetRemoveByMac(virDomainDefPtr def, const virMacAddrPtr mac);
+virDomainNetDefPtr virDomainNetRemove(virDomainDefPtr def, size_t i);
 
 int virDomainHostdevInsert(virDomainDefPtr def, virDomainHostdevDefPtr hostdev);
 virDomainHostdevDefPtr
@@ -2274,9 +2272,6 @@ VIR_ENUM_DECL(virDomainCpuPlacementMode)
 
 VIR_ENUM_DECL(virDomainStartupPolicy)
 
-virDomainNetDefPtr virDomainNetFind(virDomainDefPtr def,
-                                    const char *device);
-
 # define VIR_CONNECT_LIST_DOMAINS_FILTERS_ACTIVE   \
                 (VIR_CONNECT_LIST_DOMAINS_ACTIVE | \
                  VIR_CONNECT_LIST_DOMAINS_INACTIVE)
diff --git a/src/libvirt_private.syms b/src/libvirt_private.syms
index 699c9a3..ce6b9d1 100644
--- a/src/libvirt_private.syms
+++ b/src/libvirt_private.syms
@@ -433,6 +433,7 @@ virDomainMemDumpTypeFromString;
 virDomainMemDumpTypeToString;
 virDomainNetDefFree;
 virDomainNetFind;
+virDomainNetFindIdx;
 virDomainNetGetActualBandwidth;
 virDomainNetGetActualBridgeName;
 virDomainNetGetActualDirectDev;
@@ -441,10 +442,8 @@ virDomainNetGetActualHostdev;
 virDomainNetGetActualType;
 virDomainNetGetActualVirtPortProfile;
 virDomainNetGetActualVlan;
-virDomainNetIndexByMac;
 virDomainNetInsert;
 virDomainNetRemove;
-virDomainNetRemoveByMac;
 virDomainNetTypeToString;
 virDomainNostateReasonTypeFromString;
 virDomainNostateReasonTypeToString;
diff --git a/src/qemu/qemu_driver.c b/src/qemu/qemu_driver.c
index 254f191..3838c36 100644
--- a/src/qemu/qemu_driver.c
+++ b/src/qemu/qemu_driver.c
@@ -6158,14 +6158,6 @@ qemuDomainAttachDeviceConfig(qemuCapsPtr caps,
 
     case VIR_DOMAIN_DEVICE_NET:
         net = dev->data.net;
-        if (virDomainNetIndexByMac(vmdef, &net->mac) >= 0) {
-            char macbuf[VIR_MAC_STRING_BUFLEN];
-
-            virMacAddrFormat(&net->mac, macbuf);
-            virReportError(VIR_ERR_INVALID_ARG,
-                           _("mac %s already exists"), macbuf);
-            return -1;
-        }
         if (virDomainNetInsert(vmdef, net)) {
             virReportOOMError();
             return -1;
@@ -6237,11 +6229,12 @@ qemuDomainDetachDeviceConfig(virDomainDefPtr vmdef,
                              virDomainDeviceDefPtr dev)
 {
     virDomainDiskDefPtr disk, det_disk;
-    virDomainNetDefPtr net, det_net;
+    virDomainNetDefPtr net;
     virDomainHostdevDefPtr hostdev, det_hostdev;
     virDomainLeaseDefPtr lease, det_lease;
     virDomainControllerDefPtr cont, det_cont;
     int idx;
+    char mac[VIR_MAC_STRING_BUFLEN];
 
     switch (dev->type) {
     case VIR_DOMAIN_DEVICE_DISK:
@@ -6256,15 +6249,19 @@ qemuDomainDetachDeviceConfig(virDomainDefPtr vmdef,
 
     case VIR_DOMAIN_DEVICE_NET:
         net = dev->data.net;
-        if (!(det_net = virDomainNetRemoveByMac(vmdef, &net->mac))) {
-            char macbuf[VIR_MAC_STRING_BUFLEN];
-
-            virMacAddrFormat(&net->mac, macbuf);
-            virReportError(VIR_ERR_INVALID_ARG,
-                           _("no nic of mac %s"), macbuf);
+        idx = virDomainNetFindIdx(vmdef, net);
+        if (idx == -2) {
+            virReportError(VIR_ERR_OPERATION_FAILED,
+                           _("multiple devices matching mac address %s found"),
+                           virMacAddrFormat(&net->mac, mac));
+            return -1;
+        } else if (idx < 0) {
+            virReportError(VIR_ERR_OPERATION_FAILED, "%s",
+                           _("no matching network device was found"));
             return -1;
         }
-        virDomainNetDefFree(det_net);
+        /* this is guaranteed to succeed */
+        virDomainNetDefFree(virDomainNetRemove(vmdef, idx));
         break;
 
     case VIR_DOMAIN_DEVICE_HOSTDEV: {
@@ -6319,6 +6316,8 @@ qemuDomainUpdateDeviceConfig(qemuCapsPtr caps,
     virDomainDiskDefPtr orig, disk;
     virDomainNetDefPtr net;
     int pos;
+    char mac[VIR_MAC_STRING_BUFLEN];
+
 
     switch (dev->type) {
     case VIR_DOMAIN_DEVICE_DISK:
@@ -6356,12 +6355,18 @@ qemuDomainUpdateDeviceConfig(qemuCapsPtr caps,
 
     case VIR_DOMAIN_DEVICE_NET:
         net = dev->data.net;
-        if ((pos = virDomainNetIndexByMac(vmdef, &net->mac)) < 0) {
-            char macbuf[VIR_MAC_STRING_BUFLEN];
-
-            virMacAddrFormat(&net->mac, macbuf);
-            virReportError(VIR_ERR_INVALID_ARG,
-                           _("mac %s doesn't exist"), macbuf);
+        pos = virDomainNetFindIdx(vmdef, net);
+        if (pos == -2) {
+            virMacAddrFormat(&net->mac, mac);
+            virReportError(VIR_ERR_OPERATION_FAILED,
+                           _("couldn't find matching device "
+                             "with mac address %s"), mac);
+            return -1;
+        } else if (pos < 0) {
+            virMacAddrFormat(&net->mac, mac);
+            virReportError(VIR_ERR_OPERATION_FAILED,
+                           _("couldn't find matching device "
+                             "with mac address %s"), mac);
             return -1;
         }
 
diff --git a/src/qemu/qemu_hotplug.c b/src/qemu/qemu_hotplug.c
index 7381921..0225654 100644
--- a/src/qemu/qemu_hotplug.c
+++ b/src/qemu/qemu_hotplug.c
@@ -2448,30 +2448,28 @@ qemuDomainDetachNetDevice(struct qemud_driver *driver,
                           virDomainObjPtr vm,
                           virDomainDeviceDefPtr dev)
 {
-    int i, ret = -1;
+    int detachidx, ret = -1;
     virDomainNetDefPtr detach = NULL;
     qemuDomainObjPrivatePtr priv = vm->privateData;
     int vlan;
     char *hostnet_name = NULL;
+    char mac[VIR_MAC_STRING_BUFLEN];
     virNetDevVPortProfilePtr vport = NULL;
 
-    for (i = 0 ; i < vm->def->nnets ; i++) {
-        virDomainNetDefPtr net = vm->def->nets[i];
-
-        if (!virMacAddrCmp(&net->mac, &dev->data.net->mac)) {
-            detach = net;
-            break;
+    detachidx = virDomainNetFindIdx(vm->def, dev->data.net);
+    if (detachidx == -2) {
+        virReportError(VIR_ERR_OPERATION_FAILED,
+                       _("multiple devices matching mac address %s found"),
+                       virMacAddrFormat(&dev->data.net->mac, mac));
+        goto cleanup;
         }
-    }
-
-    if (!detach) {
+    else if (detachidx < 0) {
         virReportError(VIR_ERR_OPERATION_FAILED,
-                       _("network device %02x:%02x:%02x:%02x:%02x:%02x not found"),
-                       dev->data.net->mac.addr[0], dev->data.net->mac.addr[1],
-                       dev->data.net->mac.addr[2], dev->data.net->mac.addr[3],
-                       dev->data.net->mac.addr[4], dev->data.net->mac.addr[5]);
+                       _("network device %s not found"),
+                       virMacAddrFormat(&dev->data.net->mac, mac));
         goto cleanup;
     }
+    detach = vm->def->nets[detachidx];
 
     if (virDomainNetGetActualType(detach) == VIR_DOMAIN_NET_TYPE_HOSTDEV) {
         ret = qemuDomainDetachThisHostDevice(driver, vm,
@@ -2575,7 +2573,7 @@ qemuDomainDetachNetDevice(struct qemud_driver *driver,
 cleanup:
     if (!ret) {
         networkReleaseActualDevice(detach);
-        virDomainNetRemove(vm->def, i);
+        virDomainNetRemove(vm->def, detachidx);
         virDomainNetDefFree(detach);
     }
     VIR_FREE(hostnet_name);
diff --git a/tools/virsh-domain.c b/tools/virsh-domain.c
index 0906267..0daaeb4 100644
--- a/tools/virsh-domain.c
+++ b/tools/virsh-domain.c
@@ -7692,7 +7692,7 @@ cmdDetachInterface(vshControl *ctl, const vshCmd *cmd)
     xmlDocPtr xml = NULL;
     xmlXPathObjectPtr obj=NULL;
     xmlXPathContextPtr ctxt = NULL;
-    xmlNodePtr cur = NULL;
+    xmlNodePtr cur = NULL, matchNode = NULL;
     xmlBufferPtr xml_buf = NULL;
     const char *mac =NULL, *type = NULL;
     char *doc;
@@ -7738,10 +7738,12 @@ cmdDetachInterface(vshControl *ctl, const vshCmd *cmd)
         goto cleanup;
     }
 
-    if (!mac)
+    if (!mac) {
+        matchNode = obj->nodesetval->nodeTab[0];
         goto hit;
+    }
 
-    /* search mac */
+    /* multiple possibilities, so search for matching mac */
     for (; i < obj->nodesetval->nodeNr; i++) {
         cur = obj->nodesetval->nodeTab[i]->children;
         while (cur != NULL) {
@@ -7751,14 +7753,24 @@ cmdDetachInterface(vshControl *ctl, const vshCmd *cmd)
                 diff_mac = virMacAddrCompare(tmp_mac, mac);
                 VIR_FREE(tmp_mac);
                 if (!diff_mac) {
-                    goto hit;
+                    if (matchNode) {
+                        /* this is the 2nd match, so it's ambiguous */
+                        vshError(ctl, _("Domain has multiple interfaces matching "
+                                        "mac address %s. You must use detach-device and "
+                                        "specify the device pci address to remove it."),
+                                 mac);
+                        goto cleanup;
+                    }
+                    matchNode = obj->nodesetval->nodeTab[i];
                 }
             }
             cur = cur->next;
         }
     }
-    vshError(ctl, _("No found interface whose MAC address is %s"), mac);
-    goto cleanup;
+    if (!matchNode) {
+        vshError(ctl, _("No found interface whose MAC address is %s"), mac);
+        goto cleanup;
+    }
 
  hit:
     xml_buf = xmlBufferCreate();
@@ -7767,7 +7779,7 @@ cmdDetachInterface(vshControl *ctl, const vshCmd *cmd)
         goto cleanup;
     }
 
-    if (xmlNodeDump(xml_buf, xml, obj->nodesetval->nodeTab[i], 0, 0) < 0) {
+    if (xmlNodeDump(xml_buf, xml, matchNode, 0, 0) < 0) {
         vshError(ctl, "%s", _("Failed to create XML"));
         goto cleanup;
     }
-- 
1.7.11.7


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