[PATCH V2 1/4] conf: add 'state' attribute to <hap> feature

[Jim Fehlig <jfehlig@xxxxxxxx>]

Most hypervisors use Hardware Assisted Paging by default and don't
require specifying the feature in domain conf. But some hypervisors
support disabling HAP on a per-domain basis. To enable HAP by default
yet provide a knob to disable it, extend the <hap> feature with a
'state=on|off' attribute, similar to <pvspinlock> and <vmport> features.

In the absence of <hap>, the hypervisor default (on) is used. <hap>
without the state attribute would be the same as <hap state='on'/> for
backwards compatibility. And of course <hap state='off'/> disables hap.

Signed-off-by: Jim Fehlig <jfehlig@xxxxxxxx>
---
 docs/formatdomain.html.in     | 6 ++++--
 docs/schemas/domaincommon.rng | 6 +++++-
 src/conf/domain_conf.c        | 4 ++--
 3 files changed, 11 insertions(+), 5 deletions(-)

diff --git a/docs/formatdomain.html.in b/docs/formatdomain.html.in
index 5016772..c06bcf3 100644
--- a/docs/formatdomain.html.in
+++ b/docs/formatdomain.html.in
@@ -1494,8 +1494,10 @@
       Interrupt) for the guest.
       </dd>
       <dt><code>hap</code></dt>
-      <dd>Enable use of Hardware Assisted Paging if available in
-        the hardware.
+      <dd>Depending on the <code>state</code> attribute (values <code>on</code>,
+        <code>off</code>) enable or disable use of Hardware Assisted Paging.
+        The default is <code>on</code> if the hypervisor detects availability
+        of Hardware Assisted Paging.
       </dd>
       <dt><code>viridian</code></dt>
       <dd>Enable Viridian hypervisor extensions for paravirtualizing
diff --git a/docs/schemas/domaincommon.rng b/docs/schemas/domaincommon.rng
index 67af93a..dd6e93a 100644
--- a/docs/schemas/domaincommon.rng
+++ b/docs/schemas/domaincommon.rng
@@ -4108,7 +4108,11 @@
           </optional>
           <optional>
             <element name="hap">
-              <empty/>
+              <optional>
+                <attribute name="state">
+                  <ref name="virOnOff"/>
+                </attribute>
+              </optional>
             </element>
           </optional>
           <optional>
diff --git a/src/conf/domain_conf.c b/src/conf/domain_conf.c
index 79758d4..714bbfc 100644
--- a/src/conf/domain_conf.c
+++ b/src/conf/domain_conf.c
@@ -15296,7 +15296,6 @@ virDomainDefParseXML(xmlDocPtr xml,
             /* fallthrough */
         case VIR_DOMAIN_FEATURE_ACPI:
         case VIR_DOMAIN_FEATURE_PAE:
-        case VIR_DOMAIN_FEATURE_HAP:
         case VIR_DOMAIN_FEATURE_VIRIDIAN:
         case VIR_DOMAIN_FEATURE_PRIVNET:
         case VIR_DOMAIN_FEATURE_HYPERV:
@@ -15321,6 +15320,7 @@ virDomainDefParseXML(xmlDocPtr xml,
             ctxt->node = node;
             break;
 
+        case VIR_DOMAIN_FEATURE_HAP:
         case VIR_DOMAIN_FEATURE_PMU:
         case VIR_DOMAIN_FEATURE_PVSPINLOCK:
         case VIR_DOMAIN_FEATURE_VMPORT:
@@ -22043,7 +22043,6 @@ virDomainDefFormatInternal(virDomainDefPtr def,
             switch ((virDomainFeature) i) {
             case VIR_DOMAIN_FEATURE_ACPI:
             case VIR_DOMAIN_FEATURE_PAE:
-            case VIR_DOMAIN_FEATURE_HAP:
             case VIR_DOMAIN_FEATURE_VIRIDIAN:
             case VIR_DOMAIN_FEATURE_PRIVNET:
                 switch ((virTristateSwitch) def->features[i]) {
@@ -22065,6 +22064,7 @@ virDomainDefFormatInternal(virDomainDefPtr def,
 
                 break;
 
+            case VIR_DOMAIN_FEATURE_HAP:
             case VIR_DOMAIN_FEATURE_PMU:
             case VIR_DOMAIN_FEATURE_PVSPINLOCK:
             case VIR_DOMAIN_FEATURE_VMPORT:
-- 
2.1.4

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