[Qemu-devel] [PATCH] hax: fix breakage in locking

Vincent Palatin posted 1 patch 7 years ago
Patches applied successfully (tree, apply log)
git fetch https://github.com/patchew-project/qemu tags/patchew/20170320101549.150076-1-vpalatin@chromium.org
Test checkpatch passed
Test docker passed
Test s390x passed
cpus.c | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)
[Qemu-devel] [PATCH] hax: fix breakage in locking
Posted by Vincent Palatin 7 years ago
use qemu_mutex_lock_iothread consistently in qemu_hax_cpu_thread_fn() as
done in other _thread_fn functions, instead of grabbing directly the
BQL. This way we ensure that iothread_locked is properly set.

On v2.9.0-rc0, QEMU was dying in an assertion in the mutex code when
running with '--enable-hax' either on OSX or Windows. This bug was triggered
since the code modification for multithreading added new usages of
qemu_mutex_iothread_locked.
This fixes the breakage on both platforms, I can now run again a full
Chromium OS image with HAX kernel acceleration.

Signed-off-by: Vincent Palatin <vpalatin@chromium.org>
---
 cpus.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/cpus.c b/cpus.c
index b84a392dda..167d9615e1 100644
--- a/cpus.c
+++ b/cpus.c
@@ -1344,8 +1344,9 @@ static void *qemu_hax_cpu_thread_fn(void *arg)
 {
     CPUState *cpu = arg;
     int r;
+
+    qemu_mutex_lock_iothread();
     qemu_thread_get_self(cpu->thread);
-    qemu_mutex_lock(&qemu_global_mutex);
 
     cpu->thread_id = qemu_get_thread_id();
     cpu->created = true;
-- 
2.12.0.367.g23dc2f6d3c-goog


Re: [Qemu-devel] [PATCH] hax: fix breakage in locking
Posted by Paolo Bonzini 7 years ago

On 20/03/2017 11:15, Vincent Palatin wrote:
> use qemu_mutex_lock_iothread consistently in qemu_hax_cpu_thread_fn() as
> done in other _thread_fn functions, instead of grabbing directly the
> BQL. This way we ensure that iothread_locked is properly set.
> 
> On v2.9.0-rc0, QEMU was dying in an assertion in the mutex code when
> running with '--enable-hax' either on OSX or Windows. This bug was triggered
> since the code modification for multithreading added new usages of
> qemu_mutex_iothread_locked.
> This fixes the breakage on both platforms, I can now run again a full
> Chromium OS image with HAX kernel acceleration.
> 
> Signed-off-by: Vincent Palatin <vpalatin@chromium.org>
> ---
>  cpus.c | 3 ++-
>  1 file changed, 2 insertions(+), 1 deletion(-)
> 
> diff --git a/cpus.c b/cpus.c
> index b84a392dda..167d9615e1 100644
> --- a/cpus.c
> +++ b/cpus.c
> @@ -1344,8 +1344,9 @@ static void *qemu_hax_cpu_thread_fn(void *arg)
>  {
>      CPUState *cpu = arg;
>      int r;
> +
> +    qemu_mutex_lock_iothread();
>      qemu_thread_get_self(cpu->thread);
> -    qemu_mutex_lock(&qemu_global_mutex);
>  
>      cpu->thread_id = qemu_get_thread_id();
>      cpu->created = true;
> 

Queued, thanks.

Paolo