[libvirt] [PATCH] conf: Do better job when comparing features ABI compatibility

[Peter Krempa]

The ABI compatibility check for domain features didn't check the
expanded HyperV and APIC EOI values, thus possibly allowing change in
guest ABI.

Add the check and use typecasted switch statement to warn developers
when adding a new HyperV feature.
---
 src/conf/domain_conf.c | 72 ++++++++++++++++++++++++++++++++++++++++++++++----
 1 file changed, 67 insertions(+), 5 deletions(-)

diff --git a/src/conf/domain_conf.c b/src/conf/domain_conf.c
index c4b6464..8953579 100644
--- a/src/conf/domain_conf.c
+++ b/src/conf/domain_conf.c
@@ -13354,6 +13354,72 @@ virDomainRedirFilterDefCheckABIStability(virDomainRedirFilterDefPtr src,
     return true;
 }

+
+static bool
+virDomainDefFeaturesCheckABIStability(virDomainDefPtr src,
+                                      virDomainDefPtr dst)
+{
+    size_t i;
+
+    /* basic check */
+    if (src->features != dst->features) {
+        virReportError(VIR_ERR_CONFIG_UNSUPPORTED,
+                       _("Target domain features %d does not match source %d"),
+                       dst->features, src->features);
+        return false;
+    }
+
+    /* APIC EOI */
+    if (src->apic_eoi != dst->apic_eoi) {
+        virReportError(VIR_ERR_CONFIG_UNSUPPORTED,
+                       _("State of APIC EOI differs: "
+                         "source: '%s', destination: '%s'"),
+                       virDomainFeatureStateTypeToString(src->apic_eoi),
+                       virDomainFeatureStateTypeToString(dst->apic_eoi));
+        return false;
+    }
+
+    /* hyperv */
+    if (src->features & (1 << VIR_DOMAIN_FEATURE_HYPERV)) {
+        for (i = 0; i < VIR_DOMAIN_HYPERV_LAST; i++) {
+            switch ((enum virDomainHyperv) i) {
+            case VIR_DOMAIN_HYPERV_RELAXED:
+            case VIR_DOMAIN_HYPERV_VAPIC:
+                if (src->hyperv_features[i] != dst->hyperv_features[i]) {
+                    virReportError(VIR_ERR_CONFIG_UNSUPPORTED,
+                                   _("State of HyperV enlightenment "
+                                     "feature '%s' differs: "
+                                     "source: '%s', destination: '%s'"),
+                                   virDomainHypervTypeToString(i),
+                                   virDomainFeatureStateTypeToString(src->hyperv_features[i]),
+                                   virDomainFeatureStateTypeToString(dst->hyperv_features[i]));
+                    return false;
+                }
+
+                break;
+
+            case VIR_DOMAIN_HYPERV_SPINLOCKS:
+                /* spinlock count matters! */
+                if (src->hyperv_spinlocks != dst->hyperv_spinlocks) {
+                    virReportError(VIR_ERR_CONFIG_UNSUPPORTED,
+                                   _("HyperV spinlock retry count differs: "
+                                     "source: '%u', destination: '%u'"),
+                                   src->hyperv_spinlocks,
+                                   dst->hyperv_spinlocks);
+                    return false;
+                }
+                break;
+
+            case VIR_DOMAIN_HYPERV_LAST:
+                break;
+            }
+        }
+    }
+
+    return true;
+}
+
+
 /* This compares two configurations and looks for any differences
  * which will affect the guest ABI. This is primarily to allow
  * validation of custom XML config passed in during migration
@@ -13455,12 +13521,8 @@ virDomainDefCheckABIStability(virDomainDefPtr src,
         return false;
     }

-    if (src->features != dst->features) {
-        virReportError(VIR_ERR_CONFIG_UNSUPPORTED,
-                       _("Target domain features %d does not match source %d"),
-                       dst->features, src->features);
+    if (!virDomainDefFeaturesCheckABIStability(src, dst))
         return false;
-    }

     if (src->clock.ntimers != dst->clock.ntimers) {
         virReportError(VIR_ERR_CONFIG_UNSUPPORTED, "%s",
-- 
1.8.3.2