conf: Introduce MTE domain feature

The Memory Tagging Extensions are hardware acceleration present
in some ARM processors that allow memory error detection [1].
Introduce a domain XML knob that turns them on or off.

1: https://www.arm.com/blogs/blueprint/memory-safety-arm-memory-tagging-extension
Signed-off-by: Michal Privoznik <mprivozn@redhat.com>
Reviewed-by: Martin Kletzander <mkletzan@redhat.com>

docs/formatdomain.rst

@@ -2000,6 +2000,7 @@ Hypervisors may allow certain CPU / machine features to be toggled on/off.
      <tcg>
        <tb-cache unit='MiB'>128</tb-cache>
      </tcg>
+     <mte state='on'/>
    </features>
    ...
 
@@ -2230,6 +2231,12 @@ are:
    tb-cache    The size of translation block cache size       an integer (a multiple of MiB)                      :since:`8.0.0`
    =========== ============================================== =================================================== ==============
 
+``mte``
+   Configure Memory Tagging Extensions for ARM guests. Possible values for the
+   ``state`` attribute are ``on`` and ``off``.  If the attribute is not
+   defined, the hypervisor default will be used. :since:`Since 9.4.0` (QEMU/KVM
+   only)
+
 Time keeping
 ------------
 

src/conf/domain_conf.c

@@ -181,6 +181,7 @@ VIR_ENUM_IMPL(virDomainFeature,
               "sbbc",
               "ibs",
               "tcg",
+              "mte",
 );
 
 VIR_ENUM_IMPL(virDomainCapabilitiesPolicy,
@@ -16645,7 +16646,8 @@ virDomainFeaturesDefParse(virDomainDef *def,
 
         case VIR_DOMAIN_FEATURE_HTM:
         case VIR_DOMAIN_FEATURE_NESTED_HV:
-        case VIR_DOMAIN_FEATURE_CCF_ASSIST: {
+        case VIR_DOMAIN_FEATURE_CCF_ASSIST:
+        case VIR_DOMAIN_FEATURE_MTE: {
             virTristateSwitch state;
 
             if (virXMLPropTristateSwitch(nodes[i], "state",
@@ -20486,6 +20488,7 @@ virDomainDefFeaturesCheckABIStability(virDomainDef *src,
         case VIR_DOMAIN_FEATURE_HTM:
         case VIR_DOMAIN_FEATURE_NESTED_HV:
         case VIR_DOMAIN_FEATURE_CCF_ASSIST:
+        case VIR_DOMAIN_FEATURE_MTE:
             if (src->features[i] != dst->features[i]) {
                 virReportError(VIR_ERR_CONFIG_UNSUPPORTED,
                                _("State of feature '%1$s' differs: source: '%2$s', destination: '%3$s'"),
@@ -27005,6 +27008,7 @@ virDomainDefFormatFeatures(virBuffer *buf,
         case VIR_DOMAIN_FEATURE_HTM:
         case VIR_DOMAIN_FEATURE_NESTED_HV:
         case VIR_DOMAIN_FEATURE_CCF_ASSIST:
+        case VIR_DOMAIN_FEATURE_MTE:
             switch ((virTristateSwitch) def->features[i]) {
             case VIR_TRISTATE_SWITCH_LAST:
             case VIR_TRISTATE_SWITCH_ABSENT:

src/conf/domain_conf.h

@@ -2169,6 +2169,7 @@ typedef enum {
     VIR_DOMAIN_FEATURE_SBBC,
     VIR_DOMAIN_FEATURE_IBS,
     VIR_DOMAIN_FEATURE_TCG,
+    VIR_DOMAIN_FEATURE_MTE,
 
     VIR_DOMAIN_FEATURE_LAST
 } virDomainFeature;

src/conf/schemas/domaincommon.rng

@@ -6653,6 +6653,11 @@
           <optional>
             <ref name="tcgfeatures"/>
           </optional>
+          <optional>
+            <element name="mte">
+              <ref name="featurestate"/>
+            </element>
+          </optional>
         </interleave>
       </element>
     </optional>

src/qemu/qemu_validate.c

@@ -123,6 +123,7 @@ qemuValidateDomainDefFeatures(const virDomainDef *def,
             break;
 
         case VIR_DOMAIN_FEATURE_GIC:
+        case VIR_DOMAIN_FEATURE_MTE:
             if (def->features[i] == VIR_TRISTATE_SWITCH_ON &&
                 !qemuDomainIsARMVirt(def)) {
                 virReportError(VIR_ERR_CONFIG_UNSUPPORTED,

tests/qemuxml2argvdata/aarch64-gic-v3.xml

@@ -10,6 +10,7 @@
   </os>
   <features>
     <gic version='3'/>
+    <mte state='on'/>
   </features>
   <cpu mode='host-passthrough' check='none'/>
   <clock offset='utc'/>

tests/qemuxml2xmloutdata/aarch64-gic-v3.aarch64-latest.xml

@@ -10,6 +10,7 @@
   </os>
   <features>
     <gic version='3'/>
+    <mte state='on'/>
   </features>
   <cpu mode='host-passthrough' check='none'/>
   <clock offset='utc'/>