1 files changed, 14 insertions, 8 deletions

diff --git a/target-i386/kvm.c b/target-i386/kvm.c
index 2a9953b2d4..6dc9846398 100644
--- a/target-i386/kvm.c
+++ b/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;
 
@@ -784,18 +784,24 @@ int kvm_arch_init_vcpu(CPUState *cs)
             return ret;
         }
 
-        if (banks > MCE_BANKS_DEF) {
-            banks = MCE_BANKS_DEF;
+        if (banks < (env->mcg_cap & MCG_CAP_BANKS_MASK)) {
+            error_report("kvm: Unsupported MCE bank count (QEMU = %d, KVM = %d)",
+                         (int)(env->mcg_cap & MCG_CAP_BANKS_MASK), banks);
+            return -ENOTSUP;
         }
-        mcg_cap &= MCE_CAP_DEF;
-        mcg_cap |= banks;
-        ret = kvm_vcpu_ioctl(cs, KVM_X86_SETUP_MCE, &mcg_cap);
+
+        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) {
             fprintf(stderr, "KVM_X86_SETUP_MCE: %s", strerror(-ret));
             return ret;
         }
-
-        env->mcg_cap = mcg_cap;
     }
 
     qemu_add_vm_change_state_handler(cpu_update_state, env);