target-i386: Don't set any KVM flag by default if KVM is disabled

This is a cleanup that tries to solve two small issues:

 - We don't need a separate kvm_pv_eoi_features variable just to keep a
   constant calculated at compile-time, and this style would require
   adding a separate variable (that's declared twice because of the
   CONFIG_KVM ifdef) for each feature that's going to be
   enabled/disabled by machine-type compat code.
 - The pc-1.3 code is setting the kvm_pv_eoi flag on cpuid_kvm_features
   even when KVM is disabled at runtime. This small inconsistency in
   the cpuid_kvm_features field isn't a problem today because
   cpuid_kvm_features is ignored by the TCG code, but it may cause
   unexpected problems later when refactoring the CPUID handling code.

This patch eliminates the kvm_pv_eoi_features variable and simply uses
kvm_enabled() inside the enable_kvm_pv_eoi() compat function, so it
enables kvm_pv_eoi only if KVM is enabled. I believe this makes the
behavior of enable_kvm_pv_eoi() clearer and easier to understand.
Signed-off-by: NEduardo Habkost <ehabkost@redhat.com>
Acked-by: NGleb Natapov <gleb@redhat.com>
Reviewed-by: NMarcelo Tosatti <mtosatti@redhat.com>
Signed-off-by: NAndreas Färber <afaerber@suse.de>

target-i386/cpu.c

@@ -206,22 +206,16 @@ typedef struct model_features_t {
 int check_cpuid = 0;
 int enforce_cpuid = 0;
 
-#if defined(CONFIG_KVM)
 static uint32_t kvm_default_features = (1 << KVM_FEATURE_CLOCKSOURCE) |
         (1 << KVM_FEATURE_NOP_IO_DELAY) |
         (1 << KVM_FEATURE_CLOCKSOURCE2) |
         (1 << KVM_FEATURE_ASYNC_PF) |
         (1 << KVM_FEATURE_STEAL_TIME) |
         (1 << KVM_FEATURE_CLOCKSOURCE_STABLE_BIT);
-static const uint32_t kvm_pv_eoi_features = (0x1 << KVM_FEATURE_PV_EOI);
-#else
-static uint32_t kvm_default_features = 0;
-static const uint32_t kvm_pv_eoi_features = 0;
-#endif
 
 void enable_kvm_pv_eoi(void)
 {
-    kvm_default_features |= kvm_pv_eoi_features;
+    kvm_default_features |= (1UL << KVM_FEATURE_PV_EOI);
 }
 
 void host_cpuid(uint32_t function, uint32_t count,
@@ -1602,7 +1596,9 @@ int cpu_x86_register(X86CPU *cpu, const char *cpu_model)
         goto out;
     }
 
-    def->kvm_features |= kvm_default_features;
+    if (kvm_enabled()) {
+        def->kvm_features |= kvm_default_features;
+    }
     def->ext_features |= CPUID_EXT_HYPERVISOR;
 
     if (cpu_x86_parse_featurestr(def, features) < 0) {