qemu: Implement a stub cpuArchDriver.compare() handler for arm and aarch64

Libvirt calls cpuArchDriver.compare() while doing guest migration.
We don't have any logic to distinguish between different arm and
aarch64 models that's why this patch allows migration to any host.
Signed-off-by: NOleg Strikov <oleg.strikov@canonical.com>

src/cpu/cpu_aarch64.c

@@ -108,11 +108,18 @@ AArch64Baseline(virCPUDefPtr *cpus,
     return cpu;
 }
 
+static virCPUCompareResult
+AArch64Compare(virCPUDefPtr host ATTRIBUTE_UNUSED,
+               virCPUDefPtr cpu ATTRIBUTE_UNUSED)
+{
+    return VIR_CPU_COMPARE_IDENTICAL;
+}
+
 struct cpuArchDriver cpuDriverAARCH64 = {
     .name = "aarch64",
     .arch = archs,
     .narch = ARRAY_CARDINALITY(archs),
-    .compare = NULL,
+    .compare = AArch64Compare,
     .decode = AArch64Decode,
     .encode = NULL,
     .free = AArch64DataFree,

src/cpu/cpu_arm.c

@@ -109,11 +109,18 @@ ArmBaseline(virCPUDefPtr *cpus,
     return cpu;
 }
 
+static virCPUCompareResult
+ArmCompare(virCPUDefPtr host ATTRIBUTE_UNUSED,
+           virCPUDefPtr cpu ATTRIBUTE_UNUSED)
+{
+    return VIR_CPU_COMPARE_IDENTICAL;
+}
+
 struct cpuArchDriver cpuDriverArm = {
     .name = "arm",
     .arch = archs,
     .narch = ARRAY_CARDINALITY(archs),
-    .compare = NULL,
+    .compare = ArmCompare,
     .decode = ArmDecode,
     .encode = NULL,
     .free = ArmDataFree,