Add savevm/loadvm support for MCE

[Huang Ying <ying.huang@xxxxxxxxx>]

MCE registers are saved/load into/from CPUState in
kvm_arch_save/load_regs. Because all MCE registers except for
MCG_STATUS should be preserved, MCE registers are saved before
kvm_arch_load_regs in kvm_arch_cpu_reset. To simulate the MCG_STATUS
clearing upon reset, env->mcg_status is set to 0 after saving.

Signed-off-by: Huang Ying <ying.huang@xxxxxxxxx>

---
 qemu-kvm-x86.c |   54 ++++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 54 insertions(+)

--- a/qemu-kvm-x86.c
+++ b/qemu-kvm-x86.c
@@ -803,6 +803,27 @@ static void get_seg(SegmentCache *lhs, c
 	| (rhs->avl * DESC_AVL_MASK);
 }
 
+static void kvm_load_mce_regs(CPUState *env)
+{
+#ifdef KVM_CAP_MCE
+    struct kvm_msr_entry msrs[100];
+    int rc, n, i;
+
+    if (!env->mcg_cap)
+	    return;
+
+    n = 0;
+    set_msr_entry(&msrs[n++], MSR_MCG_STATUS, env->mcg_status);
+    set_msr_entry(&msrs[n++], MSR_MCG_CTL, env->mcg_ctl);
+    for (i = 0; i < (env->mcg_cap & 0xff) * 4; i++)
+        set_msr_entry(&msrs[n++], MSR_MC0_CTL + i, env->mce_banks[i]);
+
+    rc = kvm_set_msrs(env, msrs, n);
+    if (rc == -1)
+        perror("kvm_set_msrs FAILED");
+#endif
+}
+
 void kvm_arch_load_regs(CPUState *env)
 {
     struct kvm_regs regs;
@@ -922,6 +943,8 @@ void kvm_arch_load_regs(CPUState *env)
     if (rc == -1)
         perror("kvm_set_msrs FAILED");
 
+    kvm_load_mce_regs(env);
+
     /*
      * Kernels before 2.6.33 (which correlates with !kvm_has_vcpu_events())
      * overwrote flags.TF injected via SET_GUEST_DEBUG while updating GP regs.
@@ -991,6 +1014,33 @@ void kvm_arch_load_mpstate(CPUState *env
 #endif
 }
 
+static void kvm_save_mce_regs(CPUState *env)
+{
+#ifdef KVM_CAP_MCE
+    struct kvm_msr_entry msrs[100];
+    int rc, n, i;
+
+    if (!env->mcg_cap)
+	    return;
+
+    msrs[0].index = MSR_MCG_STATUS;
+    msrs[1].index = MSR_MCG_CTL;
+    n = (env->mcg_cap & 0xff) * 4;
+    for (i = 0; i < n; i++)
+        msrs[2 + i].index = MSR_MC0_CTL + i;
+
+    rc = kvm_get_msrs(env, msrs, n + 2);
+    if (rc == -1)
+        perror("kvm_set_msrs FAILED");
+    else {
+        env->mcg_status = msrs[0].data;
+        env->mcg_ctl = msrs[1].data;
+        for (i = 0; i < n; i++)
+            env->mce_banks[i] = msrs[2 + i].data;
+    }
+#endif
+}
+
 void kvm_arch_save_regs(CPUState *env)
 {
     struct kvm_regs regs;
@@ -1148,6 +1198,7 @@ void kvm_arch_save_regs(CPUState *env)
         }
     }
     kvm_arch_save_mpstate(env);
+    kvm_save_mce_regs(env);
 }
 
 static void do_cpuid_ent(struct kvm_cpuid_entry2 *e, uint32_t function,
@@ -1385,6 +1436,9 @@ void kvm_arch_push_nmi(void *opaque)
 void kvm_arch_cpu_reset(CPUState *env)
 {
     kvm_arch_reset_vcpu(env);
+    /* MCE registers except MCG_STATUS should be unchanged across reset */
+    kvm_save_mce_regs(env);
+    env->mcg_status = 0;
     kvm_arch_load_regs(env);
     kvm_put_vcpu_events(env);
     if (!cpu_is_bsp(env)) {


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