[PATCH v2 04/10] conf: Introduce memAccess to <memory/>

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Now that NVDIMM has found its way into libvirt, users might want
to fine tune some settings for each module separately. One such
setting is 'share=on|off' for the memory-backend-file object.
This setting - just like its name suggest already - enables
sharing the nvdimm module with other applications. Under the hood
it controls whether qemu mmaps() the file as MAP_PRIVATE or
MAP_SHARED.

Yet again, we have such config knob in domain XML, but it's just
an attribute to numa <cell/>. This does not give fine enough
tuning on per-memdevice basis so we need to have the attribute
for each device too.

Signed-off-by: Michal Privoznik <mprivozn@xxxxxxxxxx>
---
 docs/formatdomain.html.in                          | 15 ++++++-
 docs/schemas/domaincommon.rng                      | 19 ++++++---
 src/conf/domain_conf.c                             | 15 ++++++-
 src/conf/domain_conf.h                             |  2 +
 src/libvirt_private.syms                           |  2 +
 ...emuxml2argv-memory-hotplug-nvdimm-memAccess.xml | 49 ++++++++++++++++++++++
 6 files changed, 93 insertions(+), 9 deletions(-)
 create mode 100644 tests/qemuxml2argvdata/qemuxml2argv-memory-hotplug-nvdimm-memAccess.xml

diff --git a/docs/formatdomain.html.in b/docs/formatdomain.html.in
index 657df8f..06fe50d 100644
--- a/docs/formatdomain.html.in
+++ b/docs/formatdomain.html.in
@@ -1356,7 +1356,7 @@
       <span class='since'>Since 1.2.9</span> the optional attribute
       <code>memAccess</code> can control whether the memory is to be
       mapped as "shared" or "private".  This is valid only for
-      hugepages-backed memory.
+      hugepages-backed memory and nvdimm modules.
     </p>
 
     <p>
@@ -6724,7 +6724,7 @@ qemu-kvm -net nic,model=? /dev/null
 <pre>
   ...
   &lt;devices&gt;
-    &lt;memory model='dimm'&gt;
+    &lt;memory model='dimm' memAccess='private'&gt;
       &lt;target&gt;
         &lt;size unit='KiB'&gt;524287&lt;/size&gt;
         &lt;node&gt;0&lt;/node&gt;
@@ -6762,6 +6762,17 @@ qemu-kvm -net nic,model=? /dev/null
         </p>
       </dd>
 
+      <dt><code>memAccess</code></dt>
+      <dd>
+        <p>
+          Then there is optional attribute <code>memAccess</code>
+          (<span class="since">Since 2.2.0</span>) that allows
+          uses to fine tune mapping of the memory on per module
+          basis. Values are the same as for numa &lt;cell/&gt;:
+          <code>shared</code> and <code>private</code>.
+        </p>
+      </dd>
+
       <dt><code>source</code></dt>
       <dd>
         <p>
diff --git a/docs/schemas/domaincommon.rng b/docs/schemas/domaincommon.rng
index e6ad452..3e9d342 100644
--- a/docs/schemas/domaincommon.rng
+++ b/docs/schemas/domaincommon.rng
@@ -4467,6 +4467,15 @@
     </element>
   </define>
 
+  <define name="memAccess">
+    <attribute name="memAccess">
+      <choice>
+        <value>shared</value>
+        <value>private</value>
+      </choice>
+    </attribute>
+  </define>
+
   <define name="numaCell">
     <element name="cell">
       <optional>
@@ -4486,12 +4495,7 @@
         </attribute>
       </optional>
       <optional>
-        <attribute name="memAccess">
-          <choice>
-            <value>shared</value>
-            <value>private</value>
-          </choice>
-        </attribute>
+        <ref name="memAccess"/>
       </optional>
     </element>
   </define>
@@ -4725,6 +4729,9 @@
           <value>nvdimm</value>
         </choice>
       </attribute>
+      <optional>
+        <ref name="memAccess"/>
+      </optional>
       <interleave>
         <optional>
           <ref name="memorydev-source"/>
diff --git a/src/conf/domain_conf.c b/src/conf/domain_conf.c
index cb5a053..84f76dd 100644
--- a/src/conf/domain_conf.c
+++ b/src/conf/domain_conf.c
@@ -13245,6 +13245,15 @@ virDomainMemoryDefParseXML(xmlNodePtr memdevNode,
     }
     VIR_FREE(tmp);
 
+    tmp = virXMLPropString(memdevNode, "memAccess");
+    if (tmp &&
+        (def->memAccess = virNumaMemAccessTypeFromString(tmp)) <= 0) {
+        virReportError(VIR_ERR_XML_ERROR,
+                       _("invalid memAccess mode '%s'"), tmp);
+        goto error;
+    }
+    VIR_FREE(tmp);
+
     /* source */
     if ((node = virXPathNode("./source", ctxt)) &&
         virDomainMemorySourceDefParseXML(node, ctxt, def) < 0)
@@ -21800,7 +21809,11 @@ virDomainMemoryDefFormat(virBufferPtr buf,
 {
     const char *model = virDomainMemoryModelTypeToString(def->model);
 
-    virBufferAsprintf(buf, "<memory model='%s'>\n", model);
+    virBufferAsprintf(buf, "<memory model='%s'", model);
+    if (def->memAccess)
+        virBufferAsprintf(buf, " memAccess='%s'",
+                          virNumaMemAccessTypeToString(def->memAccess));
+    virBufferAddLit(buf, ">\n");
     virBufferAdjustIndent(buf, 2);
 
     if (virDomainMemorySourceDefFormat(buf, def) < 0)
diff --git a/src/conf/domain_conf.h b/src/conf/domain_conf.h
index 4e6a9bf..213768d 100644
--- a/src/conf/domain_conf.h
+++ b/src/conf/domain_conf.h
@@ -1945,6 +1945,8 @@ typedef enum {
 } virDomainMemoryModel;
 
 struct _virDomainMemoryDef {
+    virNumaMemAccess memAccess;
+
     /* source */
     virBitmapPtr sourceNodes;
     unsigned long long pagesize; /* kibibytes */
diff --git a/src/libvirt_private.syms b/src/libvirt_private.syms
index 419c33d..024c3e6 100644
--- a/src/libvirt_private.syms
+++ b/src/libvirt_private.syms
@@ -2058,6 +2058,8 @@ virNumaGetNodeMemory;
 virNumaGetPageInfo;
 virNumaGetPages;
 virNumaIsAvailable;
+virNumaMemAccessTypeFromString;
+virNumaMemAccessTypeToString;
 virNumaNodeIsAvailable;
 virNumaNodesetIsAvailable;
 virNumaSetPagePoolSize;
diff --git a/tests/qemuxml2argvdata/qemuxml2argv-memory-hotplug-nvdimm-memAccess.xml b/tests/qemuxml2argvdata/qemuxml2argv-memory-hotplug-nvdimm-memAccess.xml
new file mode 100644
index 0000000..4ebea01
--- /dev/null
+++ b/tests/qemuxml2argvdata/qemuxml2argv-memory-hotplug-nvdimm-memAccess.xml
@@ -0,0 +1,49 @@
+<domain type='qemu'>
+  <name>QEMUGuest1</name>
+  <uuid>c7a5fdbd-edaf-9455-926a-d65c16db1809</uuid>
+  <maxMemory slots='16' unit='KiB'>1099511627776</maxMemory>
+  <memory unit='KiB'>1267710</memory>
+  <currentMemory unit='KiB'>1267710</currentMemory>
+  <vcpu placement='static' cpuset='0-1'>2</vcpu>
+  <os>
+    <type arch='i686' machine='pc'>hvm</type>
+    <boot dev='hd'/>
+  </os>
+  <idmap>
+    <uid start='0' target='1000' count='10'/>
+    <gid start='0' target='1000' count='10'/>
+  </idmap>
+  <cpu>
+    <topology sockets='2' cores='1' threads='1'/>
+    <numa>
+      <cell id='0' cpus='0-1' memory='219136' unit='KiB'/>
+    </numa>
+  </cpu>
+  <clock offset='utc'/>
+  <on_poweroff>destroy</on_poweroff>
+  <on_reboot>restart</on_reboot>
+  <on_crash>destroy</on_crash>
+  <devices>
+    <emulator>/usr/bin/qemu</emulator>
+    <disk type='block' device='disk'>
+      <source dev='/dev/HostVG/QEMUGuest1'/>
+      <target dev='hda' bus='ide'/>
+      <address type='drive' controller='0' bus='0' target='0' unit='0'/>
+    </disk>
+    <controller type='ide' index='0'/>
+    <controller type='usb' index='0'/>
+    <controller type='pci' index='0' model='pci-root'/>
+    <input type='mouse' bus='ps2'/>
+    <input type='keyboard' bus='ps2'/>
+    <memballoon model='virtio'/>
+    <memory model='nvdimm' memAccess='private'>
+      <source>
+        <path>/tmp/nvdimm</path>
+      </source>
+      <target>
+        <size unit='KiB'>523264</size>
+        <node>0</node>
+      </target>
+    </memory>
+  </devices>
+</domain>
-- 
2.8.4

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