[18/22] kvm: Unconditionally reenter kernel after IO exits

Submitted by Jan Kiszka on Jan. 27, 2011, 1:10 p.m.

Details

Message ID 0582f3f257268d48afadbbce19328837a2175c75.1296133797.git.jan.kiszka@siemens.com
State New
Headers show

Commit Message

Jan Kiszka Jan. 27, 2011, 1:10 p.m.
KVM requires to reenter the kernel after IO exits in order to complete
instruction emulation. Failing to do so will leave the kernel state
inconsistently behind. To ensure that we will get back ASAP, we issue a
self-signal that will cause KVM_RUN to return once the pending
operations are completed.

This patch also fixes the missing exit_request check in kvm_cpu_exec in
the CONFIG_IOTHREAD case.

Signed-off-by: Jan Kiszka <jan.kiszka@siemens.com>
CC: Gleb Natapov <gleb@redhat.com>
---
 kvm-all.c |   20 +++++++++++---------
 1 files changed, 11 insertions(+), 9 deletions(-)

Patch hide | download patch | download mbox

diff --git a/kvm-all.c b/kvm-all.c
index 46ecc1c..d961697 100644
--- a/kvm-all.c
+++ b/kvm-all.c
@@ -199,7 +199,6 @@  int kvm_pit_in_kernel(void)
     return kvm_state->pit_in_kernel;
 }
 
-
 int kvm_init_vcpu(CPUState *env)
 {
     KVMState *s = kvm_state;
@@ -899,23 +898,26 @@  int kvm_cpu_exec(CPUState *env)
     }
 
     do {
-#ifndef CONFIG_IOTHREAD
-        if (env->exit_request) {
-            DPRINTF("interrupt exit requested\n");
-            ret = 0;
-            break;
-        }
-#endif
-
         if (env->kvm_vcpu_dirty) {
             kvm_arch_put_registers(env, KVM_PUT_RUNTIME_STATE);
             env->kvm_vcpu_dirty = 0;
         }
 
         kvm_arch_pre_run(env, run);
+        if (env->exit_request) {
+            DPRINTF("interrupt exit requested\n");
+            /*
+             * KVM requires us to reenter the kernel after IO exits to complete
+             * instruction emulation. This self-signal will ensure that we
+             * leave ASAP again.
+             */
+            qemu_cpu_kick_self();
+        }
         cpu_single_env = NULL;
         qemu_mutex_unlock_iothread();
+
         ret = kvm_vcpu_ioctl(env, KVM_RUN, 0);
+
         qemu_mutex_lock_iothread();
         cpu_single_env = env;
         kvm_arch_post_run(env, run);