conf: Don't mangle vcpu placement randomly

https://bugzilla.redhat.com/show_bug.cgi?id=1170492

In one of our previous commits (dc8b7ce7) we've done a functional
change even though it was intended as pure refactor. The problem is,
that the following XML:

 <vcpu placement='static' current='2'>6</vcpu>
 <cputune>
   <emulatorpin cpuset='1-3'/>
 </cputune>
 <numatune>
   <memory mode='strict' placement='auto'/>
 </numatune>

gets translated into this one:

 <vcpu placement='auto' current='2'>6</vcpu>
 <cputune>
   <emulatorpin cpuset='1-3'/>
 </cputune>
 <numatune>
   <memory mode='strict' placement='auto'/>
 </numatune>

We should not change the vcpu placement mode. Moreover, we're doing
something similar in case of emulatorpin and iothreadpin. If they were
set, but vcpu placement was auto, we've mistakenly removed them from
the domain XML even though we are able to set them independently on
vcpus.

Signed-off-by: Michal Privoznik <mprivozn@redhat.com>

docs/formatdomain.html.in

@@ -577,14 +577,12 @@
        <dt><code>emulatorpin</code></dt>
        <dd>
          The optional <code>emulatorpin</code> element specifies which of host
-         physical CPUs the "emulator", a subset of a domain not including vcpu,
-         will be pinned to. If this is omitted, and attribute
+         physical CPUs the "emulator", a subset of a domain not including vcpu
+         or iothreads will be pinned to. If this is omitted, and attribute
          <code>cpuset</code> of element <code>vcpu</code> is not specified,
          "emulator" is pinned to all the physical CPUs by default. It contains
          one required attribute <code>cpuset</code> specifying which physical
-         CPUs to pin to. NB, <code>emulatorpin</code> is not allowed if
-         attribute <code>placement</code> of element <code>vcpu</code> is
-         "auto".
+         CPUs to pin to.
        </dd>
        <dt><code>iothreadpin</code></dt>
        <dd>
@@ -598,8 +596,6 @@
          <code>iothread</code> value begins at "1" through the number of
           <a href="#elementsIOThreadsAllocation"><code>iothreads</code></a>
          allocated to the domain. A value of "0" is not permitted.
-         NB, <code>iothreadpin</code> is not allowed if attribute
-         <code>placement</code> of element <code>vcpu</code> is "auto".
         <span class="since">Since 1.2.9</span>
        </dd>
       <dt><code>shares</code></dt>

src/conf/domain_conf.c

@@ -13084,28 +13084,20 @@ virDomainDefParseXML(xmlDocPtr xml,
         goto error;
     }
 
-    /* Ignore emulatorpin if <vcpu> placement is "auto", they
-     * conflicts with each other, and <vcpu> placement can't be
-     * simply ignored, as <numatune>'s placement defaults to it.
-     */
     if (n) {
-        if (def->placement_mode != VIR_DOMAIN_CPU_PLACEMENT_MODE_AUTO) {
-            if (n > 1) {
-                virReportError(VIR_ERR_XML_ERROR, "%s",
-                               _("only one emulatorpin is supported"));
-                VIR_FREE(nodes);
-                goto error;
-            }
-
-            def->cputune.emulatorpin = virDomainVcpuPinDefParseXML(nodes[0],
-                                                                   ctxt, 0,
-                                                                   true, false);
-
-            if (!def->cputune.emulatorpin)
-                goto error;
-        } else {
-            VIR_WARN("Ignore emulatorpin for <vcpu> placement is 'auto'");
+        if (n > 1) {
+            virReportError(VIR_ERR_XML_ERROR, "%s",
+                           _("only one emulatorpin is supported"));
+            VIR_FREE(nodes);
+            goto error;
         }
+
+        def->cputune.emulatorpin = virDomainVcpuPinDefParseXML(nodes[0],
+                                                               ctxt, 0,
+                                                               true, false);
+
+        if (!def->cputune.emulatorpin)
+            goto error;
     }
     VIR_FREE(nodes);
 
@@ -13116,38 +13108,28 @@ virDomainDefParseXML(xmlDocPtr xml,
         goto error;
     }
 
-    /* Ignore iothreadpin if <vcpu> placement is "auto", they
-     * conflict with each other, and <vcpu> placement can't be
-     * simply ignored, as <numatune>'s placement defaults to it.
-     */
-    if (n) {
-        if (def->placement_mode != VIR_DOMAIN_CPU_PLACEMENT_MODE_AUTO) {
-            if (VIR_ALLOC_N(def->cputune.iothreadspin, n) < 0)
-                goto error;
+    if (n && VIR_ALLOC_N(def->cputune.iothreadspin, n) < 0)
+        goto error;
 
-            for (i = 0; i < n; i++) {
-                virDomainVcpuPinDefPtr iothreadpin = NULL;
-                iothreadpin = virDomainVcpuPinDefParseXML(nodes[i], ctxt,
-                                                          def->iothreads,
-                                                          false, true);
-                if (!iothreadpin)
-                    goto error;
+    for (i = 0; i < n; i++) {
+        virDomainVcpuPinDefPtr iothreadpin = NULL;
+        iothreadpin = virDomainVcpuPinDefParseXML(nodes[i], ctxt,
+                                                  def->iothreads,
+                                                  false, true);
+        if (!iothreadpin)
+            goto error;
 
-                if (virDomainVcpuPinIsDuplicate(def->cputune.iothreadspin,
-                                                def->cputune.niothreadspin,
-                                                iothreadpin->vcpuid)) {
-                    virReportError(VIR_ERR_INTERNAL_ERROR, "%s",
-                                   _("duplicate iothreadpin for same iothread"));
-                    virDomainVcpuPinDefFree(iothreadpin);
-                    goto error;
-                }
-
-                def->cputune.iothreadspin[def->cputune.niothreadspin++] =
-                    iothreadpin;
-            }
-        } else {
-            VIR_WARN("Ignore iothreadpin for <vcpu> placement is 'auto'");
+        if (virDomainVcpuPinIsDuplicate(def->cputune.iothreadspin,
+                                        def->cputune.niothreadspin,
+                                        iothreadpin->vcpuid)) {
+            virReportError(VIR_ERR_INTERNAL_ERROR, "%s",
+                           _("duplicate iothreadpin for same iothread"));
+            virDomainVcpuPinDefFree(iothreadpin);
+            goto error;
         }
+
+        def->cputune.iothreadspin[def->cputune.niothreadspin++] =
+            iothreadpin;
     }
     VIR_FREE(nodes);
 
@@ -13185,7 +13167,9 @@ virDomainDefParseXML(xmlDocPtr xml,
                                   ctxt) < 0)
         goto error;
 
-    if (virDomainNumatuneHasPlacementAuto(def->numatune) && !def->cpumask)
+    if (virDomainNumatuneHasPlacementAuto(def->numatune) &&
+        !def->cpumask && !def->cputune.vcpupin &&
+        !def->cputune.emulatorpin && !def->cputune.iothreadspin)
         def->placement_mode = VIR_DOMAIN_CPU_PLACEMENT_MODE_AUTO;
 
     if ((n = virXPathNodeSet("./resource", ctxt, &nodes)) < 0) {

tests/qemuxml2argvdata/qemuxml2argv-cputune-numatune.xml

@@ -0,0 +1,37 @@
+<domain type='kvm'>
+  <name>dummy2</name>
+  <uuid>4d92ec27-9ebf-400b-ae91-20c71c647c19</uuid>
+  <memory unit='KiB'>131072</memory>
+  <currentMemory unit='KiB'>65536</currentMemory>
+  <vcpu placement='auto' current='2'>6</vcpu>
+  <iothreads>2</iothreads>
+  <cputune>
+    <emulatorpin cpuset='1-3'/>
+    <iothreadpin iothread='1' cpuset='2'/>
+  </cputune>
+  <numatune>
+    <memory mode='strict' placement='auto'/>
+  </numatune>
+  <os>
+    <type arch='x86_64' machine='pc-q35-2.3'>hvm</type>
+    <boot dev='hd'/>
+  </os>
+  <clock offset='utc'/>
+  <on_poweroff>destroy</on_poweroff>
+  <on_reboot>restart</on_reboot>
+  <on_crash>destroy</on_crash>
+  <devices>
+    <emulator>/usr/bin/qemu-system-x86_64</emulator>
+    <controller type='sata' index='0'>
+      <address type='pci' domain='0x0000' bus='0x00' slot='0x1f' function='0x2'/>
+    </controller>
+    <controller type='pci' index='0' model='pcie-root'/>
+    <controller type='pci' index='1' model='dmi-to-pci-bridge'>
+      <address type='pci' domain='0x0000' bus='0x00' slot='0x1e' function='0x0'/>
+    </controller>
+    <controller type='pci' index='2' model='pci-bridge'>
+      <address type='pci' domain='0x0000' bus='0x01' slot='0x01' function='0x0'/>
+    </controller>
+    <memballoon model='none'/>
+  </devices>
+</domain>

tests/qemuxml2argvdata/qemuxml2argv-vcpu-placement-static.xml

@@ -0,0 +1,37 @@
+<domain type='kvm'>
+  <name>dummy2</name>
+  <uuid>4d92ec27-9ebf-400b-ae91-20c71c647c19</uuid>
+  <memory unit='KiB'>131072</memory>
+  <currentMemory unit='KiB'>65536</currentMemory>
+  <vcpu placement='static' current='2'>6</vcpu>
+  <iothreads>2</iothreads>
+  <cputune>
+    <emulatorpin cpuset='1-3'/>
+    <iothreadpin iothread='1' cpuset='2'/>
+  </cputune>
+  <numatune>
+    <memory mode='strict' placement='auto'/>
+  </numatune>
+  <os>
+    <type arch='x86_64' machine='pc-q35-2.3'>hvm</type>
+    <boot dev='hd'/>
+  </os>
+  <clock offset='utc'/>
+  <on_poweroff>destroy</on_poweroff>
+  <on_reboot>restart</on_reboot>
+  <on_crash>destroy</on_crash>
+  <devices>
+    <emulator>/usr/bin/qemu-system-x86_64</emulator>
+    <controller type='sata' index='0'>
+      <address type='pci' domain='0x0000' bus='0x00' slot='0x1f' function='0x2'/>
+    </controller>
+    <controller type='pci' index='0' model='pcie-root'/>
+    <controller type='pci' index='1' model='dmi-to-pci-bridge'>
+      <address type='pci' domain='0x0000' bus='0x00' slot='0x1e' function='0x0'/>
+    </controller>
+    <controller type='pci' index='2' model='pci-bridge'>
+      <address type='pci' domain='0x0000' bus='0x01' slot='0x01' function='0x0'/>
+    </controller>
+    <memballoon model='none'/>
+  </devices>
+</domain>

tests/qemuxml2xmltest.c

@@ -310,6 +310,8 @@ mymain(void)
     DO_TEST("blkiotune-device");
     DO_TEST("cputune");
     DO_TEST("cputune-zero-shares");
+    DO_TEST("cputune-numatune");
+    DO_TEST("vcpu-placement-static");
 
     DO_TEST("smp");
     DO_TEST("iothreads");