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[libvirt] [PATCH v2 1/2] Add support for locking domain's memory pages



The following XML configuration can be used to request all domain's
memory pages to be kept locked in host's memory (i.e., domain's memory
pages will not be swapped out):

      <memoryBacking>
        <locked/>
      </memoryBacking>
---
 docs/formatdomain.html.in     | 26 ++++++++++++++++----------
 docs/schemas/domaincommon.rng |  5 +++++
 src/conf/domain_conf.c        | 20 +++++++++++---------
 src/conf/domain_conf.h        |  1 +
 4 files changed, 33 insertions(+), 19 deletions(-)

diff --git a/docs/formatdomain.html.in b/docs/formatdomain.html.in
index c6c0728..a71c484 100644
--- a/docs/formatdomain.html.in
+++ b/docs/formatdomain.html.in
@@ -595,22 +595,28 @@
   &lt;memoryBacking&gt;
     &lt;hugepages/&gt;
     &lt;nosharepages/&gt;
+    &lt;locked/&gt;
   &lt;/memoryBacking&gt;
   ...
 &lt;/domain&gt;
 </pre>
 
+    <p>The optional <code>memoryBacking</code> element may contain several
+      elements that influence how virtual memory pages are backed by host
+      pages.</p>
+
     <dl>
-      <dt><code>memoryBacking</code></dt>
-      <dd>The optional <code>memoryBacking</code> element has two
-        optional elements. The element <code>hugepages</code> tells
-        the hypervisor that the guest should have its memory allocated
-        using hugepages instead of the normal native page size. And the
-        optional element <code>nosharepages</code>
-        (<span class="since">since 1.0.6</span>) tells the hypervisor
-        that share pages (memory merge, KSM) should be disabled on guest
-        startup.
-      </dd>
+      <dt><code>hugepages</code></dt>
+      <dd>This tells the hypervisor that the guest should have its memory
+        allocated using hugepages instead of the normal native page size.</dd>
+      <dt><code>nosharepages</code></dt>
+      <dd>Instructs hypervisor to disable shared pages (memory merge, KSM) for
+        this domain. <span class="since">Since 1.0.6</span></dd>
+      <dt><code>locked</code></dt>
+      <dd>When set and supported by the hypervisor, memory pages belonging
+        to the domain will be locked in host's memory and the host will not
+        be allowed to swap them out.
+        <span class="since">Since 1.0.6</span></dd>
     </dl>
 
 
diff --git a/docs/schemas/domaincommon.rng b/docs/schemas/domaincommon.rng
index 8c7c1bc..018ca0b 100644
--- a/docs/schemas/domaincommon.rng
+++ b/docs/schemas/domaincommon.rng
@@ -501,6 +501,11 @@
                 <empty/>
               </element>
             </optional>
+            <optional>
+              <element name="locked">
+                <empty/>
+              </element>
+            </optional>
           </interleave>
         </element>
       </optional>
diff --git a/src/conf/domain_conf.c b/src/conf/domain_conf.c
index 11978db..b5e5d4d 100644
--- a/src/conf/domain_conf.c
+++ b/src/conf/domain_conf.c
@@ -10411,6 +10411,9 @@ virDomainDefParseXML(xmlDocPtr xml,
     if ((node = virXPathNode("./memoryBacking/nosharepages", ctxt)))
         def->mem.nosharepages = true;
 
+    if (virXPathBoolean("boolean(./memoryBacking/locked)", ctxt))
+        def->mem.locked = true;
+
     /* Extract blkio cgroup tunables */
     if (virXPathUInt("string(./blkiotune/weight)", ctxt,
                      &def->blkio.weight) < 0)
@@ -15766,17 +15769,16 @@ virDomainDefFormatInternal(virDomainDefPtr def,
         def->mem.swap_hard_limit)
         virBufferAddLit(buf, "  </memtune>\n");
 
-    if (def->mem.hugepage_backed || def->mem.nosharepages)
+    if (def->mem.hugepage_backed || def->mem.nosharepages || def->mem.locked) {
         virBufferAddLit(buf, "  <memoryBacking>\n");
-
-    if (def->mem.hugepage_backed)
-        virBufferAddLit(buf, "    <hugepages/>\n");
-
-    if (def->mem.nosharepages)
-        virBufferAddLit(buf, "    <nosharepages/>\n");
-
-    if (def->mem.hugepage_backed || def->mem.nosharepages)
+        if (def->mem.hugepage_backed)
+            virBufferAddLit(buf, "    <hugepages/>\n");
+        if (def->mem.nosharepages)
+            virBufferAddLit(buf, "    <nosharepages/>\n");
+        if (def->mem.locked)
+            virBufferAddLit(buf, "    <locked/>\n");
         virBufferAddLit(buf, "  </memoryBacking>\n");
+    }
 
     virBufferAddLit(buf, "  <vcpu");
     virBufferAsprintf(buf, " placement='%s'",
diff --git a/src/conf/domain_conf.h b/src/conf/domain_conf.h
index f40bfc6..a10b2ab 100644
--- a/src/conf/domain_conf.h
+++ b/src/conf/domain_conf.h
@@ -1863,6 +1863,7 @@ struct _virDomainDef {
         unsigned long long cur_balloon; /* in kibibytes */
         bool hugepage_backed;
         bool nosharepages;
+        bool locked;
         int dump_core; /* enum virDomainMemDump */
         unsigned long long hard_limit; /* in kibibytes */
         unsigned long long soft_limit; /* in kibibytes */
-- 
1.8.2.1


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