Re: [Qemu-devel] [PATCH for-2.3 v2] cpus: Don't kick un-realized cpus.

[Paolo Bonzini]

On 23/03/2015 11:48, Peter Crosthwaite wrote:
> following a464982499b2f637f6699e3d03e0a9d2e0b5288b, it's now possible for
> there to be attempts to take the BQL before CPUs have been realized in
> cases where a machine model inits peripherals before the first CPU.
> 
> BQL lock aquisition kicks the first_cpu, leading to a segfault if this
> happens pre-realize. Guard the CPU kick routine to perform no action for
> a CPU that doesn't exist or doesn't have a thread yet.
> 
> There was a fix to this with commit
> 6b49809c597331803ea941eadda813e5bb4e8fe2, but the check there misses
> the case where the CPU has been inited and not realized. Strengthen the
> check to make sure that the first_cpu has a thread (i.e. it is
> realized) before allowing the kick.
> 
> Signed-off-by: Peter Crosthwaite <address@hidden>
> ---
> Fixed since V1:
> Change implementation to match 6b49809c597331803ea941eadda813e5bb4e8fe2
> ---
>  cpus.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/cpus.c b/cpus.c
> index 314df16..e6dcae3 100644
> --- a/cpus.c
> +++ b/cpus.c
> @@ -1119,7 +1119,7 @@ bool qemu_in_vcpu_thread(void)
>  void qemu_mutex_lock_iothread(void)
>  {
>      atomic_inc(&iothread_requesting_mutex);
> -    if (!tcg_enabled() || !first_cpu) {
> +    if (!tcg_enabled() || !first_cpu || !first_cpu->thread) {
>          qemu_mutex_lock(&qemu_global_mutex);
>          atomic_dec(&iothread_requesting_mutex);
>      } else {
> 

Thanks, applied.

Paolo