cpu: Introduce virCPUCopyMigratable

This new internal API makes a copy of virCPUDef while removing all
features which would block migration. It uses cpu_map.xml as a database
of such features, which should only be used as a fallback when we cannot
get the data from a hypervisor. The main goal of this API is to decouple
this filtering from virCPUUpdate so that the hypervisor driver can
filter the features according to the hypervisor.

Signed-off-by: Jiri Denemark <jdenemar@redhat.com>

src/cpu/cpu.c

@@ -1130,3 +1130,34 @@ virCPUExpandFeatures(virArch arch,
     VIR_DEBUG("nfeatures=%zu", cpu->nfeatures);
     return 0;
 }
+
+
+/**
+ * virCPUCopyMigratable:
+ *
+ * @arch: CPU architecture
+ * @cpu: CPU definition to be copied
+ *
+ * Makes a copy of @cpu with all features which would block migration removed.
+ * If this doesn't make sense for a given architecture, the function returns a
+ * plain copy of @cpu (i.e., a copy with no features removed).
+ *
+ * Returns the copy of the CPU or NULL on error.
+ */
+virCPUDefPtr
+virCPUCopyMigratable(virArch arch,
+                     virCPUDefPtr cpu)
+{
+    struct cpuArchDriver *driver;
+
+    VIR_DEBUG("arch=%s, cpu=%p, model=%s",
+              virArchToString(arch), cpu, NULLSTR(cpu->model));
+
+    if (!(driver = cpuGetSubDriver(arch)))
+        return NULL;
+
+    if (driver->copyMigratable)
+        return driver->copyMigratable(cpu);
+    else
+        return virCPUDefCopy(cpu);
+}

src/cpu/cpu.h

@@ -118,6 +118,9 @@ typedef int
 typedef int
 (*virCPUArchExpandFeatures)(virCPUDefPtr cpu);
 
+typedef virCPUDefPtr
+(*virCPUArchCopyMigratable)(virCPUDefPtr cpu);
+
 struct cpuArchDriver {
     const char *name;
     const virArch *arch;
@@ -138,6 +141,7 @@ struct cpuArchDriver {
     virCPUArchTranslate translate;
     virCPUArchConvertLegacy convertLegacy;
     virCPUArchExpandFeatures expandFeatures;
+    virCPUArchCopyMigratable copyMigratable;
 };
 
 
@@ -254,6 +258,10 @@ int
 virCPUExpandFeatures(virArch arch,
                      virCPUDefPtr cpu);
 
+virCPUDefPtr
+virCPUCopyMigratable(virArch arch,
+                     virCPUDefPtr cpu);
+
 /* virCPUDataFormat and virCPUDataParse are implemented for unit tests only and
  * have no real-life usage
  */

src/cpu/cpu_x86.c

@@ -2903,6 +2903,30 @@ virCPUx86ExpandFeatures(virCPUDefPtr cpu)
 }
 
 
+static virCPUDefPtr
+virCPUx86CopyMigratable(virCPUDefPtr cpu)
+{
+    virCPUDefPtr copy;
+    virCPUx86MapPtr map;
+
+    if (!(map = virCPUx86GetMap()))
+        return NULL;
+
+    if (!(copy = virCPUDefCopyWithoutModel(cpu)))
+        return NULL;
+
+    if (virCPUDefCopyModelFilter(copy, cpu, false,
+                                 x86FeatureIsMigratable, map) < 0)
+        goto error;
+
+    return copy;
+
+ error:
+    virCPUDefFree(copy);
+    return NULL;
+}
+
+
 int
 virCPUx86DataAddCPUID(virCPUDataPtr cpuData,
                       const virCPUx86CPUID *cpuid)
@@ -2978,4 +3002,5 @@ struct cpuArchDriver cpuDriverX86 = {
     .getModels  = virCPUx86GetModels,
     .translate  = virCPUx86Translate,
     .expandFeatures = virCPUx86ExpandFeatures,
+    .copyMigratable = virCPUx86CopyMigratable,
 };

src/libvirt_private.syms

@@ -1017,6 +1017,7 @@ virCPUCheckFeature;
 virCPUCompare;
 virCPUCompareXML;
 virCPUConvertLegacy;
+virCPUCopyMigratable;
 virCPUDataCheckFeature;
 virCPUDataFormat;
 virCPUDataFree;