cpuBaseline: Detect empty set of common features

In case the set of CPUs has no features in common, report incompatible
CPUs instead of returning the simplest CPU model with all features
disabled.

diff --git a/src/cpu/cpu_x86.c b/src/cpu/cpu_x86.c
index 30a2db68fdc9b88534da638446d96ec92ba08f35..0266ce94a9f31058ee8630676ec5e6a813dc1088 100644 (file)
--- a/src/cpu/cpu_x86.c
+++ b/src/cpu/cpu_x86.c
@@ -233,6 +233,26 @@ x86DataSubtract(union cpuData *data1,
 }
 
 
+static bool
+x86DataIsEmpty(union cpuData *data)
+{
+    struct cpuX86cpuid zero = { 0, 0, 0, 0, 0 };
+    unsigned int i;
+
+    for (i = 0; i < data->x86.basic_len; i++) {
+        if (!x86cpuidMatch(data->x86.basic + i, &zero))
+            return false;
+    }
+
+    for (i = 0; i < data->x86.extended_len; i++) {
+        if (!x86cpuidMatch(data->x86.extended + i, &zero))
+            return false;
+    }
+
+    return true;
+}
+
+
 static union cpuData *
 x86DataFromModel(const struct x86_model *model)
 {
@@ -1363,6 +1383,12 @@ x86Baseline(virCPUDefPtr *cpus,
     if (!(data = x86DataFromModel(base_model)))
         goto no_memory;
 
+    if (x86DataIsEmpty(data)) {
+        virCPUReportError(VIR_ERR_OPERATION_FAILED,
+                "%s", _("CPUs are incompatible"));
+        goto error;
+    }
+
     if (x86Decode(cpu, data, models, nmodels, NULL) < 0)
         goto error;