[PATCH 08/13] kvm: x86: Inject pending MCE events on state writeback

[Jan Kiszka <jan.kiszka@xxxxxxxxxxx>]

The current way of injecting MCE events without updating of and
synchronizing with the CPUState is broken and causes spurious
corruptions of the MCE-related parts of the CPUState.

As a first step towards a fix, enhance the state writeback code with
support for injecting events that are pending in the CPUState. A pending
exception will then be signaled via cpu_interrupt(CPU_INTERRUPT_MCE).
And, just like for TCG, we need to leave the halt state when
CPU_INTERRUPT_MCE is pending (left broken for the to-be-removed old KVM
code).

This will also allow to unify TCG and KVM injection code.

Signed-off-by: Jan Kiszka <jan.kiszka@xxxxxxxxxxx>
CC: Huang Ying <ying.huang@xxxxxxxxx>
CC: Hidetoshi Seto <seto.hidetoshi@xxxxxxxxxxxxxx>
CC: Jin Dongming <jin.dongming@xxxxxxxxxxxxxxxxxx>
---
 target-i386/kvm.c |   75 +++++++++++++++++++++++++++++++++++++++++++++++++---
 1 files changed, 70 insertions(+), 5 deletions(-)

diff --git a/target-i386/kvm.c b/target-i386/kvm.c
index f909661..46f45db 100644
--- a/target-i386/kvm.c
+++ b/target-i386/kvm.c
@@ -467,6 +467,44 @@ void kvm_inject_x86_mce(CPUState *cenv, int bank, uint64_t status,
 #endif /* !KVM_CAP_MCE*/
 }
 
+static int kvm_inject_mce_oldstyle(CPUState *env)
+{
+#ifdef KVM_CAP_MCE
+    if (kvm_has_vcpu_events()) {
+        return 0;
+    }
+    if (env->interrupt_request & CPU_INTERRUPT_MCE) {
+        unsigned int bank, bank_num = env->mcg_cap & 0xff;
+        struct kvm_x86_mce mce;
+
+        /* We must not raise CPU_INTERRUPT_MCE if it's not supported. */
+        assert(env->mcg_cap);
+
+        env->interrupt_request &= ~CPU_INTERRUPT_MCE;
+
+        /*
+         * There must be at least one bank in use if CPU_INTERRUPT_MCE was set.
+         * Find it and use its values for the event injection.
+         */
+        for (bank = 0; bank < bank_num; bank++) {
+            if (env->mce_banks[bank * 4 + 1] & MCI_STATUS_VAL) {
+                break;
+            }
+        }
+        assert(bank < bank_num);
+
+        mce.bank = bank;
+        mce.status = env->mce_banks[bank * 4 + 1];
+        mce.mcg_status = env->mcg_status;
+        mce.addr = env->mce_banks[bank * 4 + 2];
+        mce.misc = env->mce_banks[bank * 4 + 3];
+
+        return kvm_vcpu_ioctl(env, KVM_X86_SET_MCE, &mce);
+    }
+#endif /* KVM_CAP_MCE */
+    return 0;
+}
+
 static void cpu_update_state(void *opaque, int running, int reason)
 {
     CPUState *env = opaque;
@@ -1375,10 +1413,25 @@ static int kvm_put_vcpu_events(CPUState *env, int level)
         return 0;
     }
 
-    events.exception.injected = (env->exception_injected >= 0);
-    events.exception.nr = env->exception_injected;
-    events.exception.has_error_code = env->has_error_code;
-    events.exception.error_code = env->error_code;
+    if (env->interrupt_request & CPU_INTERRUPT_MCE) {
+        /* We must not raise CPU_INTERRUPT_MCE if it's not supported. */
+        assert(env->mcg_cap);
+
+        env->interrupt_request &= ~CPU_INTERRUPT_MCE;
+        if (env->exception_injected == EXCP08_DBLE) {
+            /* this means triple fault */
+            qemu_system_reset_request();
+            env->exit_request = 1;
+        }
+        events.exception.injected = 1;
+        events.exception.nr = EXCP12_MCHK;
+        events.exception.has_error_code = 0;
+    } else {
+        events.exception.injected = (env->exception_injected >= 0);
+        events.exception.nr = env->exception_injected;
+        events.exception.has_error_code = env->has_error_code;
+        events.exception.error_code = env->error_code;
+    }
 
     events.interrupt.injected = (env->interrupt_injected >= 0);
     events.interrupt.nr = env->interrupt_injected;
@@ -1539,6 +1592,11 @@ int kvm_arch_put_registers(CPUState *env, int level)
     if (ret < 0) {
         return ret;
     }
+    /* must be before kvm_put_msrs */
+    ret = kvm_inject_mce_oldstyle(env);
+    if (ret < 0) {
+        return ret;
+    }
     ret = kvm_put_msrs(env, level);
     if (ret < 0) {
         return ret;
@@ -1678,10 +1736,17 @@ void kvm_arch_post_run(CPUState *env, struct kvm_run *run)
 int kvm_arch_process_irqchip_events(CPUState *env)
 {
     if (kvm_irqchip_in_kernel()) {
+        if (env->interrupt_request & CPU_INTERRUPT_MCE) {
+            kvm_cpu_synchronize_state(env);
+            if (env->mp_state == KVM_MP_STATE_HALTED) {
+                env->mp_state = KVM_MP_STATE_RUNNABLE;
+            }
+        }
         return 0;
     }
 
-    if (env->interrupt_request & (CPU_INTERRUPT_HARD | CPU_INTERRUPT_NMI)) {
+    if (env->interrupt_request &
+        (CPU_INTERRUPT_HARD | CPU_INTERRUPT_NMI | CPU_INTERRUPT_MCE)) {
         env->halted = 0;
     }
     if (env->interrupt_request & CPU_INTERRUPT_INIT) {
-- 
1.7.1

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