[PATCH v2 5/5] conf: add deprecated_features attribute

[Collin Walling <walling@xxxxxxxxxxxxx>]

Add a new a attribute, deprecated_features='on|off' to the <cpu>
element.  This is used to toggle features flagged as deprecated on the
CPU model on or off.  When this attribute is paired with 'on',
deprecated features will not be filtered.  When paired with 'off', any
CPU features that are flagged as deprecated will be listed under the
CPU model with the 'disable' policy.

Example:

  <cpu mode='host-model' check='partial' deprecated_features='off'/>

The absence of this attribute is equivalent to the 'on' option.

The deprecated features that will populate the domain XML are the same
features that result in the virsh domcapabilities command with the
--disable-deprecated-features argument present.

It is recommended to define a domain XML with this attribute set to
'off' to ensure migration to machines that may outright drop these
features in the future.

Signed-off-by: Collin Walling <walling@xxxxxxxxxxxxx>
---
 src/conf/cpu_conf.c           | 10 ++++++++++
 src/conf/cpu_conf.h           |  1 +
 src/conf/schemas/cputypes.rng | 12 ++++++++++++
 src/qemu/qemu_process.c       |  4 ++++
 4 files changed, 27 insertions(+)

diff --git a/src/conf/cpu_conf.c b/src/conf/cpu_conf.c
index dcc164d165..a9910e2195 100644
--- a/src/conf/cpu_conf.c
+++ b/src/conf/cpu_conf.c
@@ -238,6 +238,7 @@ virCPUDefCopyWithoutModel(const virCPUDef *cpu)
     copy->mode = cpu->mode;
     copy->match = cpu->match;
     copy->check = cpu->check;
+    copy->deprecated_feats = cpu->deprecated_feats;
     copy->fallback = cpu->fallback;
     copy->sockets = cpu->sockets;
     copy->dies = cpu->dies;
@@ -450,6 +451,11 @@ virCPUDefParseXML(xmlXPathContextPtr ctxt,
         if (virXMLPropEnum(ctxt->node, "check", virCPUCheckTypeFromString,
                            VIR_XML_PROP_NONE, &def->check) < 0)
             return -1;
+
+        if (virXMLPropTristateSwitch(ctxt->node, "deprecated_features",
+                                     VIR_XML_PROP_NONE,
+                                     &def->deprecated_feats) < 0)
+            return -1;
     }
 
     if (def->type == VIR_CPU_TYPE_HOST) {
@@ -748,6 +754,10 @@ virCPUDefFormatBufFull(virBuffer *buf,
             virBufferAsprintf(&attributeBuf, " migratable='%s'",
                               virTristateSwitchTypeToString(def->migratable));
         }
+
+        if (def->deprecated_feats == VIR_TRISTATE_SWITCH_OFF) {
+            virBufferAddLit(&attributeBuf, " deprecated_features='off'");
+        }
     }
 
     /* Format children */
diff --git a/src/conf/cpu_conf.h b/src/conf/cpu_conf.h
index f71d942ce6..28e26303ef 100644
--- a/src/conf/cpu_conf.h
+++ b/src/conf/cpu_conf.h
@@ -161,6 +161,7 @@ struct _virCPUDef {
     virCPUMaxPhysAddrDef *addr;
     virHostCPUTscInfo *tsc;
     virTristateSwitch migratable; /* for host-passthrough mode */
+    virTristateSwitch deprecated_feats;
 };
 
 virCPUDef *virCPUDefNew(void);
diff --git a/src/conf/schemas/cputypes.rng b/src/conf/schemas/cputypes.rng
index 3a8910e09f..b94b08eb5a 100644
--- a/src/conf/schemas/cputypes.rng
+++ b/src/conf/schemas/cputypes.rng
@@ -34,6 +34,15 @@
     </attribute>
   </define>
 
+  <define name="cpuDeprecatedFeatures">
+    <attribute name="deprecated_features">
+      <choice>
+        <value>on</value>
+        <value>off</value>
+      </choice>
+    </attribute>
+  </define>
+
   <define name="cpuModel">
     <element name="model">
       <optional>
@@ -439,6 +448,9 @@
       <optional>
         <ref name="cpuCheck"/>
       </optional>
+      <optional>
+        <ref name="cpuDeprecatedFeatures"/>
+      </optional>
       <optional>
         <attribute name="migratable">
           <ref name="virOnOff"/>
diff --git a/src/qemu/qemu_process.c b/src/qemu/qemu_process.c
index bee7a39e4e..c06ca1a833 100644
--- a/src/qemu/qemu_process.c
+++ b/src/qemu/qemu_process.c
@@ -6399,6 +6399,10 @@ qemuProcessUpdateGuestCPU(virDomainDef *def,
                                 &def->os.arch) < 0)
         return -1;
 
+    if (def->cpu->deprecated_feats == VIR_TRISTATE_SWITCH_OFF) {
+        virQEMUCapsUpdateCPUDeprecatedFeatures(qemuCaps, def->virtType, def->cpu);
+    }
+
     return 0;
 }
 
-- 
2.45.1