[Qemu-devel] [PATCH 1/2] target-i386: Don't set any KVM flag by default if KVM is disabled

[Eduardo Habkost <ehabkost@redhat.com>]

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/disable
   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 incosistency 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
CONFIG_KVM and 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: Eduardo Habkost <ehabkost@redhat.com>
---
Cc: kvm@vger.kernel.org
Cc: Michael S. Tsirkin <mst@redhat.com>
Cc: Gleb Natapov <gleb@redhat.com>
Cc: Marcelo Tosatti <mtosatti@redhat.com>
---
 target-i386/cpu.c | 7 ++++---
 1 file changed, 4 insertions(+), 3 deletions(-)

diff --git a/target-i386/cpu.c b/target-i386/cpu.c
index 82685dc..808001a 100644
--- a/target-i386/cpu.c
+++ b/target-i386/cpu.c
@@ -145,15 +145,16 @@ static uint32_t kvm_default_features = (1 << KVM_FEATURE_CLOCKSOURCE) |
         (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;
+#ifdef CONFIG_KVM
+    if (kvm_enabled())
+        kvm_default_features |= (1UL << KVM_FEATURE_PV_EOI);
+#endif
 }
 
 void host_cpuid(uint32_t function, uint32_t count,
-- 
1.7.11.7