[libvirt PATCH 1/2] conf: add killpriv v2 attribute for virtiofs

[Ján Tomko]

Add a new attribute to control the killpriv feature:

  <filesystem>
    ...
    <binary>
      <killpriv v2='off'/>
    </binary>
  </filesystem>

https://bugzilla.redhat.com/show_bug.cgi?id=1972571

Signed-off-by: Ján Tomko <jtomko at redhat.com>
---
 docs/formatdomain.rst                             |  4 ++++
 docs/schemas/domaincommon.rng                     |  7 +++++++
 src/conf/domain_conf.c                            | 15 +++++++++++++++
 src/conf/domain_conf.h                            |  1 +
 .../qemuxml2argvdata/vhost-user-fs-fd-memory.xml  |  1 +
 5 files changed, 28 insertions(+)

diff --git a/docs/formatdomain.rst b/docs/formatdomain.rst
index d4f30bb8af..73ff8bce51 100644
--- a/docs/formatdomain.rst
+++ b/docs/formatdomain.rst
@@ -3313,6 +3313,7 @@ A directory on the host that can be accessed directly from the guest.
          <binary path='/usr/libexec/virtiofsd' xattr='on'>
             <cache mode='always'/>
             <sandbox mode='namespace'/>
+            <killpriv v2='on'/>
             <lock posix='on' flock='on'/>
          </binary>
          <source dir='/path'/>
@@ -3447,6 +3448,9 @@ A directory on the host that can be accessed directly from the guest.
    ``chroot``, see the
    `virtiofsd documentation <https://qemu.readthedocs.io/en/latest/tools/virtiofsd.html>`__
    for more details. ( :since:`Since 7.2.0` )
+   The ``killpriv`` element with the attribute ``v2`` (values: ``on`` or ``off``)
+   can be used to disable the killpriv capability which is used to improve performance
+   by expecting writes to reset some security attributes. ( :since:`Since 8.0.0` )
 ``source``
    The resource on the host that is being accessed in the guest. The ``name``
    attribute must be used with ``type='template'``, and the ``dir`` attribute
diff --git a/docs/schemas/domaincommon.rng b/docs/schemas/domaincommon.rng
index 7fa5c2b8b5..5701bbe193 100644
--- a/docs/schemas/domaincommon.rng
+++ b/docs/schemas/domaincommon.rng
@@ -3057,6 +3057,13 @@
             </optional>
           </element>
         </optional>
+        <optional>
+          <element name="killpriv">
+            <attribute name="v2">
+              <ref name="virOnOff"/>
+            </attribute>
+          </element>
+        </optional>
       </interleave>
     </element>
   </define>
diff --git a/src/conf/domain_conf.c b/src/conf/domain_conf.c
index 5691b8d2d5..2a1802a3d5 100644
--- a/src/conf/domain_conf.c
+++ b/src/conf/domain_conf.c
@@ -9874,6 +9874,7 @@ virDomainFSDefParseXML(virDomainXMLOption *xmlopt,
         g_autofree char *sandbox = virXPathString("string(./binary/sandbox/@mode)", ctxt);
         g_autofree char *posix_lock = virXPathString("string(./binary/lock/@posix)", ctxt);
         g_autofree char *flock = virXPathString("string(./binary/lock/@flock)", ctxt);
+        g_autofree char *killpriv_v2 = virXPathString("string(./binary/killpriv/@v2)", ctxt);
         int val;
 
         if (queue_size && virStrToLong_ull(queue_size, NULL, 10, &def->queue_size) < 0) {
@@ -9932,6 +9933,15 @@ virDomainFSDefParseXML(virDomainXMLOption *xmlopt,
             }
             def->flock = val;
         }
+
+        if (killpriv_v2) {
+            if ((val = virTristateSwitchTypeFromString(killpriv_v2)) <= 0) {
+                virReportError(VIR_ERR_CONFIG_UNSUPPORTED,
+                               _("unknown killpriv_v2 value '%s'"), killpriv_v2);
+                goto error;
+            }
+            def->killpriv_v2 = val;
+        }
     }
 
     if (source == NULL && def->type != VIR_DOMAIN_FS_TYPE_RAM
@@ -24197,6 +24207,11 @@ virDomainFSDefFormat(virBuffer *buf,
                               virTristateSwitchTypeToString(def->flock));
         }
 
+        if (def->killpriv_v2 != VIR_TRISTATE_SWITCH_ABSENT) {
+            virBufferAsprintf(&binaryBuf, "<killpriv v2='%s'/>\n",
+                              virTristateSwitchTypeToString(def->killpriv_v2));
+        }
+
         virXMLFormatElement(&binaryBuf, "lock", &lockAttrBuf, NULL);
     }
 
diff --git a/src/conf/domain_conf.h b/src/conf/domain_conf.h
index 144ba4dd12..4619fcbfd1 100644
--- a/src/conf/domain_conf.h
+++ b/src/conf/domain_conf.h
@@ -892,6 +892,7 @@ struct _virDomainFSDef {
     virTristateSwitch posix_lock;
     virTristateSwitch flock;
     virDomainFSSandboxMode sandbox;
+    virTristateSwitch killpriv_v2;
     virDomainVirtioOptions *virtio;
     virObject *privateData;
 };
diff --git a/tests/qemuxml2argvdata/vhost-user-fs-fd-memory.xml b/tests/qemuxml2argvdata/vhost-user-fs-fd-memory.xml
index abddf0870b..2f44a1593a 100644
--- a/tests/qemuxml2argvdata/vhost-user-fs-fd-memory.xml
+++ b/tests/qemuxml2argvdata/vhost-user-fs-fd-memory.xml
@@ -31,6 +31,7 @@
       <binary path='/usr/libexec/virtiofsd' xattr='on'>
         <cache mode='always'/>
         <sandbox mode='chroot'/>
+        <killpriv v2='on'/>
         <lock posix='off' flock='off'/>
       </binary>
       <source dir='/path'/>
-- 
2.31.1