Currently, multi threaded TCG with > 1 VCPU gets stuck during IPL, when
the bios tries to switch to the loaded kernel via DIAG 308.

As run_on_cpu() is used, we run into a deadlock after handling the reset.
We need the iolock (just like KVM).

Signed-off-by: David Hildenbrand <david@redhat.com>
---
 target/s390x/misc_helper.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/target/s390x/misc_helper.c b/target/s390x/misc_helper.c
index 4afd90b969..d272851e1c 100644
--- a/target/s390x/misc_helper.c
+++ b/target/s390x/misc_helper.c
@@ -103,7 +103,9 @@ void HELPER(diag)(CPUS390XState *env, uint32_t r1, uint32_t r3, uint32_t num)
         break;
     case 0x308:
         /* ipl */
+        qemu_mutex_lock_iothread();
         handle_diag_308(env, r1, r3);
+        qemu_mutex_unlock_iothread();
         r = 0;
         break;
     case 0x288:
-- 
2.13.6

On 16.11.2017 18:05, David Hildenbrand wrote:
> Currently, multi threaded TCG with > 1 VCPU gets stuck during IPL, when
> the bios tries to switch to the loaded kernel via DIAG 308.
> 
> As run_on_cpu() is used, we run into a deadlock after handling the reset.
> We need the iolock (just like KVM).
> 
> Signed-off-by: David Hildenbrand <david@redhat.com>
> ---
>  target/s390x/misc_helper.c | 2 ++
>  1 file changed, 2 insertions(+)
> 
> diff --git a/target/s390x/misc_helper.c b/target/s390x/misc_helper.c
> index 4afd90b969..d272851e1c 100644
> --- a/target/s390x/misc_helper.c
> +++ b/target/s390x/misc_helper.c
> @@ -103,7 +103,9 @@ void HELPER(diag)(CPUS390XState *env, uint32_t r1, uint32_t r3, uint32_t num)
>          break;
>      case 0x308:
>          /* ipl */
> +        qemu_mutex_lock_iothread();
>          handle_diag_308(env, r1, r3);
> +        qemu_mutex_unlock_iothread();
>          r = 0;
>          break;
>      case 0x288:
> 

Reviewed-by: Thomas Huth <thuth@redhat.com>