kvm: Set cpu_single_env only once

As we have thread-local cpu_single_env now and KVM uses exactly one
thread per VCPU, we can drop the cpu_single_env updates from the loop
and initialize this variable only once during setup.
Signed-off-by: NJan Kiszka <jan.kiszka@siemens.com>
Signed-off-by: NAvi Kivity <avi@redhat.com>

cpus.c

@@ -714,6 +714,7 @@ static void *qemu_kvm_cpu_thread_fn(void *arg)
     qemu_mutex_lock(&qemu_global_mutex);
     qemu_thread_get_self(env->thread);
     env->thread_id = qemu_get_thread_id();
+    cpu_single_env = env;
 
     r = kvm_init_vcpu(env);
     if (r < 0) {

kvm-all.c

@@ -1118,8 +1118,6 @@ int kvm_cpu_exec(CPUState *env)
         return EXCP_HLT;
     }
 
-    cpu_single_env = env;
-
     do {
         if (env->kvm_vcpu_dirty) {
             kvm_arch_put_registers(env, KVM_PUT_RUNTIME_STATE);
@@ -1136,13 +1134,11 @@ int kvm_cpu_exec(CPUState *env)
              */
             qemu_cpu_kick_self();
         }
-        cpu_single_env = NULL;
         qemu_mutex_unlock_iothread();
 
         run_ret = kvm_vcpu_ioctl(env, KVM_RUN, 0);
 
         qemu_mutex_lock_iothread();
-        cpu_single_env = env;
         kvm_arch_post_run(env, run);
 
         kvm_flush_coalesced_mmio_buffer();
@@ -1206,7 +1202,6 @@ int kvm_cpu_exec(CPUState *env)
     }
 
     env->exit_request = 0;
-    cpu_single_env = NULL;
     return ret;
 }