target-i386: kvm: Print warning when clearing mcg_cap bits

Instead of silently clearing mcg_cap bits when the host doesn't
support them, print a warning when doing that.
Signed-off-by: NEduardo Habkost <ehabkost@redhat.com>
[Avoid \n at end of error_report. - Paolo]
Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>
Message-Id: <1448471956-66873-10-git-send-email-pbonzini@redhat.com>

target-i386/kvm.c

@@ -774,7 +774,7 @@ int kvm_arch_init_vcpu(CPUState *cs)
         && (env->features[FEAT_1_EDX] & (CPUID_MCE | CPUID_MCA)) ==
            (CPUID_MCE | CPUID_MCA)
         && kvm_check_extension(cs->kvm_state, KVM_CAP_MCE) > 0) {
-        uint64_t mcg_cap;
+        uint64_t mcg_cap, unsupported_caps;
         int banks;
         int ret;
 
@@ -790,6 +790,12 @@ int kvm_arch_init_vcpu(CPUState *cs)
             return -ENOTSUP;
         }
 
+        unsupported_caps = env->mcg_cap & ~(mcg_cap | MCG_CAP_BANKS_MASK);
+        if (unsupported_caps) {
+            error_report("warning: Unsupported MCG_CAP bits: 0x%" PRIx64,
+                         unsupported_caps);
+        }
+
         env->mcg_cap &= mcg_cap | MCG_CAP_BANKS_MASK;
         ret = kvm_vcpu_ioctl(cs, KVM_X86_SETUP_MCE, &env->mcg_cap);
         if (ret < 0) {