[Qemu-devel] [PATCH qom-cpu-next 2/3] target-i386: Introduce X86CPU.filtered_features field

[Eduardo Habkost <ehabkost@redhat.com>]

This field will contain the feature bits that were filtered out because
of missing host support.

Signed-off-by: Eduardo Habkost <ehabkost@redhat.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
---
Changes v11 -> v12:
 * Rebase on top of qom-cpu-next
   (commit bd87d2a - target-i386: Use FeatureWord loop on filter_features_for_kvm())
---
 target-i386/cpu-qom.h | 3 +++
 target-i386/cpu.c     | 9 ++++++---
 2 files changed, 9 insertions(+), 3 deletions(-)

diff --git a/target-i386/cpu-qom.h b/target-i386/cpu-qom.h
index f890f1c..849cedf 100644
--- a/target-i386/cpu-qom.h
+++ b/target-i386/cpu-qom.h
@@ -65,6 +65,9 @@ typedef struct X86CPU {
     /*< public >*/
 
     CPUX86State env;
+
+    /* Features that were filtered out because of missing host capabilities */
+    uint32_t filtered_features[FEATURE_WORDS];
 } X86CPU;
 
 static inline X86CPU *x86_env_get_cpu(CPUX86State *env)
diff --git a/target-i386/cpu.c b/target-i386/cpu.c
index 3857514..38793bc 100644
--- a/target-i386/cpu.c
+++ b/target-i386/cpu.c
@@ -1698,9 +1698,12 @@ static void filter_features_for_kvm(X86CPU *cpu)
 
     for (w = 0; w < FEATURE_WORDS; w++) {
         FeatureWordInfo *wi = &feature_word_info[w];
-        env->features[w] &= kvm_arch_get_supported_cpuid(s, wi->cpuid_eax,
-                                                            wi->cpuid_ecx,
-                                                            wi->cpuid_reg);
+        uint32_t host_feat = kvm_arch_get_supported_cpuid(s, wi->cpuid_eax,
+                                                             wi->cpuid_ecx,
+                                                             wi->cpuid_reg);
+        uint32_t requested_features = env->features[w];
+        env->features[w] &= host_feat;
+        cpu->filtered_features[w] = requested_features & ~env->features[w];
     }
 }
 #endif
-- 
1.8.1.4