[PATCH] accel/kvm/kvm-all: Handle register access errors

[Akihiko Odaki]

A register access error typically means something seriously wrong
happened so that anything bad can happen after that and recovery is
impossible.
Even failing one register access is catastorophic as
architecture-specific code are not written so that it torelates such
failures.

Make sure the VM stop and nothing worse happens if such an error occurs.

Signed-off-by: Akihiko Odaki <akihiko.odaki@daynix.com>
---
 accel/kvm/kvm-all.c | 32 ++++++++++++++++++++++++++++----
 1 file changed, 28 insertions(+), 4 deletions(-)

diff --git a/accel/kvm/kvm-all.c b/accel/kvm/kvm-all.c
index f99b0becd8..9e848f750e 100644
--- a/accel/kvm/kvm-all.c
+++ b/accel/kvm/kvm-all.c
@@ -2709,7 +2709,13 @@ bool kvm_cpu_check_are_resettable(void)
 static void do_kvm_cpu_synchronize_state(CPUState *cpu, run_on_cpu_data arg)
 {
     if (!cpu->vcpu_dirty) {
-        kvm_arch_get_registers(cpu);
+        int ret = kvm_arch_get_registers(cpu);
+        if (ret) {
+            error_report("Failed to get registers: %s", strerror(-ret));
+            cpu_dump_state(cpu, stderr, CPU_DUMP_CODE);
+            vm_stop(RUN_STATE_INTERNAL_ERROR);
+        }
+
         cpu->vcpu_dirty = true;
     }
 }
@@ -2723,7 +2729,13 @@ void kvm_cpu_synchronize_state(CPUState *cpu)
 
 static void do_kvm_cpu_synchronize_post_reset(CPUState *cpu, run_on_cpu_data 
arg)
 {
-    kvm_arch_put_registers(cpu, KVM_PUT_RESET_STATE);
+    int ret = kvm_arch_put_registers(cpu, KVM_PUT_RESET_STATE);
+    if (ret) {
+        error_report("Failed to put registers after reset: %s", 
strerror(-ret));
+        cpu_dump_state(cpu, stderr, CPU_DUMP_CODE);
+        vm_stop(RUN_STATE_INTERNAL_ERROR);
+    }
+
     cpu->vcpu_dirty = false;
 }
 
@@ -2734,7 +2746,12 @@ void kvm_cpu_synchronize_post_reset(CPUState *cpu)
 
 static void do_kvm_cpu_synchronize_post_init(CPUState *cpu, run_on_cpu_data 
arg)
 {
-    kvm_arch_put_registers(cpu, KVM_PUT_FULL_STATE);
+    int ret = kvm_arch_put_registers(cpu, KVM_PUT_FULL_STATE);
+    if (ret) {
+        error_report("Failed to put registers after init: %s", strerror(-ret));
+        exit(1);
+    }
+
     cpu->vcpu_dirty = false;
 }
 
@@ -2827,7 +2844,14 @@ int kvm_cpu_exec(CPUState *cpu)
         MemTxAttrs attrs;
 
         if (cpu->vcpu_dirty) {
-            kvm_arch_put_registers(cpu, KVM_PUT_RUNTIME_STATE);
+            ret = kvm_arch_put_registers(cpu, KVM_PUT_RUNTIME_STATE);
+            if (ret) {
+                error_report("Failed to put registers after init: %s",
+                             strerror(-ret));
+                ret = -1;
+                break;
+            }
+
             cpu->vcpu_dirty = false;
         }
 
-- 
2.38.1