From: Laine Stump <laine@redhat.com>
Date: Sat, 19 Oct 2019 05:58:07 +0000 (-0400)
Subject: qemu: avoid double reservation of PCI address for interface type='hostdev'
X-Git-Url: http://xenbits.xensource.com/gitweb?a=commitdiff_plain;h=47a7b8a96b6343d4af18ef80330f805ef031fe9b;p=libvirt.git

qemu: avoid double reservation of PCI address for interface type='hostdev'

Commit 01ca4010d86 (libvirt v5.1.0) moved address reservation for
hotplugged interface devices up to an earlier point in
qemuDomainAttachNetDevice(), because that function calls
qemuDomainSupportsNicdev() (in the case of
VIR_DOMAIN_NET_TYPE_VHOSTUSER), and qemuDomainSupportsNicdev() needs
to know the address type (for ARM machinetypes) and returns incorrect
results when the address type is "none".

This bugfix unfortunately caused a regression, because it also made PCI
address reservation happen before we noticed that the device was a
*hostdev* interface. Those interfaces are hotplugged by just calling
out to qemuDomainAttachHostdevDevice() - that function would then also
attempt to reserve the *same PCI address* that had just been reserved
in qemuDomainAttachNetDevice().

The solution is to move the bit of code that short-circuits out to
virDomainHostdevAttach() up *even earlier* so that no PCI address has
been allocated by the time it's called.

https://bugzilla.redhat.com/show_bug.cgi?id=1744523
Signed-off-by: Laine Stump <laine@redhat.com>
Reviewed-by: Andrea Bolognani <abologna@redhat.com>
---

diff --git a/src/qemu/qemu_hotplug.c b/src/qemu/qemu_hotplug.c
index fd4bafef0c..77744ed96a 100644
--- a/src/qemu/qemu_hotplug.c
+++ b/src/qemu/qemu_hotplug.c
@@ -1181,6 +1181,17 @@ qemuDomainAttachNetDevice(virQEMUDriverPtr driver,
     if (qemuAssignDeviceNetAlias(vm->def, net, -1) < 0)
         goto cleanup;
 
+    if (actualType == VIR_DOMAIN_NET_TYPE_HOSTDEV) {
+        /* This is really a "smart hostdev", so it should be attached
+         * as a hostdev (the hostdev code will reach over into the
+         * netdev-specific code as appropriate), then also added to
+         * the nets list (see cleanup:) if successful.
+         */
+        ret = qemuDomainAttachHostDevice(driver, vm,
+                                         virDomainNetGetActualHostdev(net));
+        goto cleanup;
+    }
+
     if (qemuDomainIsS390CCW(vm->def) &&
         net->info.type != VIR_DOMAIN_DEVICE_ADDRESS_TYPE_PCI &&
         virQEMUCapsGet(priv->qemuCaps, QEMU_CAPS_CCW)) {
@@ -1260,17 +1271,6 @@ qemuDomainAttachNetDevice(virQEMUDriverPtr driver,
             goto cleanup;
         break;
 
-    case VIR_DOMAIN_NET_TYPE_HOSTDEV:
-        /* This is really a "smart hostdev", so it should be attached
-         * as a hostdev (the hostdev code will reach over into the
-         * netdev-specific code as appropriate), then also added to
-         * the nets list (see cleanup:) if successful.
-         */
-        ret = qemuDomainAttachHostDevice(driver, vm,
-                                         virDomainNetGetActualHostdev(net));
-        goto cleanup;
-        break;
-
     case VIR_DOMAIN_NET_TYPE_VHOSTUSER:
         queueSize = net->driver.virtio.queues;
         if (!queueSize)
@@ -1313,6 +1313,10 @@ qemuDomainAttachNetDevice(virQEMUDriverPtr driver,
         }
         break;
 
+    case VIR_DOMAIN_NET_TYPE_HOSTDEV:
+        /* hostdev interfaces were handled earlier in this function */
+        break;
+
     case VIR_DOMAIN_NET_TYPE_SERVER:
     case VIR_DOMAIN_NET_TYPE_CLIENT:
     case VIR_DOMAIN_NET_TYPE_MCAST: