conf: introduce 'msrs' feature

Introduce the 'msrs' feature element that controls Model Specific
Registers related behaviour. At this moment it allows only
single tunable attribute "unknown":

 <msrs unknown='ignore|fault'/>

Which tells hypervisor to ignore accesses to unimplemented
Model Specific Registers. The only user of that for now is going
to be the bhyve driver.
Signed-off-by: NRoman Bogorodskiy <bogorodskiy@gmail.com>
Reviewed-by: NCole Robinson <crobinso@redhat.com>

docs/schemas/domaincommon.rng

@@ -4997,6 +4997,9 @@
               <ref name="featurestate"/>
             </element>
           </optional>
+          <optional>
+            <ref name="msrs"/>
+          </optional>
         </interleave>
       </element>
     </optional>
@@ -5245,6 +5248,17 @@
     </element>
   </define>
 
+  <define name="msrs">
+    <element name="msrs">
+      <attribute name="unknown">
+        <choice>
+          <value>ignore</value>
+          <value>fault</value>
+        </choice>
+      </attribute>
+    </element>
+  </define>
+
   <define name="address">
     <element name="address">
       <choice>

src/conf/domain_conf.c

@@ -157,6 +157,7 @@ VIR_ENUM_IMPL(virDomainFeature, VIR_DOMAIN_FEATURE_LAST,
               "vmcoreinfo",
               "htm",
               "nested-hv",
+              "msrs",
 );
 
 VIR_ENUM_IMPL(virDomainCapabilitiesPolicy, VIR_DOMAIN_CAPABILITIES_POLICY_LAST,
@@ -186,6 +187,11 @@ VIR_ENUM_IMPL(virDomainKVM, VIR_DOMAIN_KVM_LAST,
               "hidden",
 );
 
+VIR_ENUM_IMPL(virDomainMsrsUnknown, VIR_DOMAIN_MSRS_UNKNOWN_LAST,
+              "ignore",
+              "fault",
+);
+
 VIR_ENUM_IMPL(virDomainCapsFeature, VIR_DOMAIN_CAPS_FEATURE_LAST,
               "audit_control",
               "audit_write",
@@ -20365,6 +20371,7 @@ virDomainDefParseXML(xmlDocPtr xml,
         case VIR_DOMAIN_FEATURE_PRIVNET:
         case VIR_DOMAIN_FEATURE_HYPERV:
         case VIR_DOMAIN_FEATURE_KVM:
+        case VIR_DOMAIN_FEATURE_MSRS:
             def->features[val] = VIR_TRISTATE_SWITCH_ON;
             break;
 
@@ -20653,6 +20660,26 @@ virDomainDefParseXML(xmlDocPtr xml,
         def->tseg_specified = rv;
     }
 
+    if (def->features[VIR_DOMAIN_FEATURE_MSRS] == VIR_TRISTATE_SWITCH_ON) {
+        if ((node = virXPathNode("./features/msrs", ctxt)) == NULL)
+            goto error;
+
+        if (!(tmp = virXMLPropString(node, "unknown"))) {
+            virReportError(VIR_ERR_CONFIG_UNSUPPORTED,
+                           _("missing 'unknown' attribute for feature '%s'"),
+                           virDomainFeatureTypeToString(VIR_DOMAIN_FEATURE_MSRS));
+            goto error;
+        }
+
+        if ((def->msrs_features[VIR_DOMAIN_MSRS_UNKNOWN] = virDomainMsrsUnknownTypeFromString(tmp)) < 0) {
+            virReportError(VIR_ERR_CONFIG_UNSUPPORTED,
+                           _("unknown 'unknown' value '%s'"),
+                           tmp);
+            goto error;
+        }
+        VIR_FREE(tmp);
+    }
+
     if ((n = virXPathNodeSet("./features/capabilities/*", ctxt, &nodes)) < 0)
         goto error;
 
@@ -22713,6 +22740,9 @@ virDomainDefFeaturesCheckABIStability(virDomainDefPtr src,
             }
             break;
 
+        case VIR_DOMAIN_FEATURE_MSRS:
+            break;
+
         case VIR_DOMAIN_FEATURE_LAST:
             break;
         }
@@ -28768,6 +28798,14 @@ virDomainDefFormatInternal(virDomainDefPtr def,
                 }
                 break;
 
+            case VIR_DOMAIN_FEATURE_MSRS:
+                if (def->features[i] != VIR_TRISTATE_SWITCH_ON)
+                    break;
+
+                virBufferAsprintf(buf, "<msrs unknown='%s'/>\n",
+                                  virDomainMsrsUnknownTypeToString(def->msrs_features[VIR_DOMAIN_MSRS_UNKNOWN]));
+                break;
+
             /* coverity[dead_error_begin] */
             case VIR_DOMAIN_FEATURE_LAST:
                 break;

src/conf/domain_conf.h

@@ -1782,6 +1782,7 @@ typedef enum {
     VIR_DOMAIN_FEATURE_VMCOREINFO,
     VIR_DOMAIN_FEATURE_HTM,
     VIR_DOMAIN_FEATURE_NESTED_HV,
+    VIR_DOMAIN_FEATURE_MSRS,
 
     VIR_DOMAIN_FEATURE_LAST
 } virDomainFeature;
@@ -1813,6 +1814,19 @@ typedef enum {
     VIR_DOMAIN_KVM_LAST
 } virDomainKVM;
 
+typedef enum {
+    VIR_DOMAIN_MSRS_UNKNOWN = 0,
+
+    VIR_DOMAIN_MSRS_LAST
+} virDomainMsrs;
+
+typedef enum {
+    VIR_DOMAIN_MSRS_UNKNOWN_IGNORE = 0,
+    VIR_DOMAIN_MSRS_UNKNOWN_FAULT,
+
+    VIR_DOMAIN_MSRS_UNKNOWN_LAST
+} virDomainMsrsUnknown;
+
 typedef enum {
     VIR_DOMAIN_CAPABILITIES_POLICY_DEFAULT = 0,
     VIR_DOMAIN_CAPABILITIES_POLICY_ALLOW,
@@ -2466,6 +2480,7 @@ struct _virDomainDef {
     int caps_features[VIR_DOMAIN_CAPS_FEATURE_LAST];
     int hyperv_features[VIR_DOMAIN_HYPERV_LAST];
     int kvm_features[VIR_DOMAIN_KVM_LAST];
+    int msrs_features[VIR_DOMAIN_MSRS_LAST];
     unsigned int hyperv_spinlocks;
     virGICVersion gic_version;
     virDomainHPTResizing hpt_resizing;
@@ -3477,6 +3492,7 @@ VIR_ENUM_DECL(virDomainGraphicsSpiceMouseMode);
 VIR_ENUM_DECL(virDomainGraphicsVNCSharePolicy);
 VIR_ENUM_DECL(virDomainHyperv);
 VIR_ENUM_DECL(virDomainKVM);
+VIR_ENUM_DECL(virDomainMsrsUnknown);
 VIR_ENUM_DECL(virDomainRNGModel);
 VIR_ENUM_DECL(virDomainRNGBackend);
 VIR_ENUM_DECL(virDomainTPMModel);

src/qemu/qemu_domain.c

@@ -4021,6 +4021,7 @@ qemuDomainDefValidateFeatures(const virDomainDef *def,
         case VIR_DOMAIN_FEATURE_PMU:
         case VIR_DOMAIN_FEATURE_VMPORT:
         case VIR_DOMAIN_FEATURE_VMCOREINFO:
+        case VIR_DOMAIN_FEATURE_MSRS:
         case VIR_DOMAIN_FEATURE_LAST:
             break;
         }