[Qemu-devel] [PATCH 0/2] io-thread fixes

[Qemu-devel] [PATCH 0/2] io-thread fixes

[Glauber Costa]

Hi,

Our iothread still does not work reliably, but with those fixes
I can get a little bit further.

Anthony, please let me know what you think of it.

[Qemu-devel] [PATCH 1/2] unlock iothread before running vpu

[Glauber Costa]

Signed-off-by: Glauber Costa <glommer@redhat.com>
---
 kvm-all.c     |    4 ++++
 qemu-common.h |    4 ++++
 vl.c          |    9 ++++-----
 3 files changed, 12 insertions(+), 5 deletions(-)

diff --git a/kvm-all.c b/kvm-all.c
index f669c3a..d9d7e06 100644
--- a/kvm-all.c
+++ b/kvm-all.c
@@ -591,7 +591,11 @@ int kvm_cpu_exec(CPUState *env)
         }
 
         kvm_arch_pre_run(env, run);
+
+        qemu_mutex_unlock_iothread();
         ret = kvm_vcpu_ioctl(env, KVM_RUN, 0);
+        qemu_mutex_lock_iothread();
+
         kvm_arch_post_run(env, run);
 
         if (ret == -EINTR || ret == -EAGAIN) {
diff --git a/qemu-common.h b/qemu-common.h
index 74ac88f..69486ed 100644
--- a/qemu-common.h
+++ b/qemu-common.h
@@ -207,6 +207,10 @@ void qemu_notify_event(void);
 void qemu_cpu_kick(void *env);
 int qemu_cpu_self(void *env);
 
+
+void qemu_mutex_lock_iothread(void);
+void qemu_mutex_unlock_iothread(void);
+
 #ifdef CONFIG_USER_ONLY
 #define qemu_init_vcpu(env) do { } while (0)
 #else
diff --git a/vl.c b/vl.c
index c164f45..aa5047e 100644
--- a/vl.c
+++ b/vl.c
@@ -3595,14 +3595,13 @@ void qemu_notify_event(void)
     }
 }
 
-#define qemu_mutex_lock_iothread() do { } while (0)
-#define qemu_mutex_unlock_iothread() do { } while (0)
-
 void vm_stop(int reason)
 {
     do_vm_stop(reason);
 }
 
+void qemu_mutex_lock_iothread(void) {}
+void qemu_mutex_unlock_iothread(void) {}
 #else /* CONFIG_IOTHREAD */
 
 #include "qemu-thread.h"
@@ -3788,7 +3787,7 @@ static void qemu_signal_lock(unsigned int msecs)
     qemu_mutex_unlock(&qemu_fair_mutex);
 }
 
-static void qemu_mutex_lock_iothread(void)
+void qemu_mutex_lock_iothread(void)
 {
     if (kvm_enabled()) {
         qemu_mutex_lock(&qemu_fair_mutex);
@@ -3798,7 +3797,7 @@ static void qemu_mutex_lock_iothread(void)
         qemu_signal_lock(100);
 }
 
-static void qemu_mutex_unlock_iothread(void)
+void qemu_mutex_unlock_iothread(void)
 {
     qemu_mutex_unlock(&qemu_global_mutex);
 }
-- 
1.6.2.2

[Qemu-devel] [PATCH 2/2] do not issue ioctl from within the io thread

[Glauber Costa]

According to Documentation/kvm/api.txt, (and well, to common sense),
we should not be calling vcpu ioctls from within the iothread.
Since vcpu initialization issues a vcpu ioctl, move it a little bit
further in time to prevent it.

Signed-off-by: Glauber Costa <glommer@redhat.com>
---
 vl.c |    2 +-
 1 files changed, 1 insertions(+), 1 deletions(-)

diff --git a/vl.c b/vl.c
index aa5047e..89051b8 100644
--- a/vl.c
+++ b/vl.c
@@ -3675,6 +3675,7 @@ static void *kvm_cpu_thread_fn(void *arg)
 
     block_io_signals();
     qemu_thread_self(env->thread);
+    kvm_init_vcpu(env);
 
     /* signal CPU creation */
     qemu_mutex_lock(&qemu_global_mutex);
@@ -3870,7 +3871,6 @@ static void tcg_init_vcpu(void *_env)
 
 static void kvm_start_vcpu(CPUState *env)
 {
-    kvm_init_vcpu(env);
     env->thread = qemu_mallocz(sizeof(QemuThread));
     env->halt_cond = qemu_mallocz(sizeof(QemuCond));
     qemu_cond_init(env->halt_cond);
-- 
1.6.2.2