Re: [PATCH] hw/ppc: Fix iothread locking in the 405 code

[Cédric Le Goater]

On 10/6/21 09:11, Thomas Huth wrote:
> When using u-boot as firmware with the taihu board, QEMU aborts with
> this assertion:
>
>   ERROR:../accel/tcg/tcg-accel-ops.c:79:tcg_handle_interrupt: assertion failed:
>    (qemu_mutex_iothread_locked())
>
> Running QEMU with "-d in_asm" shows that the crash happens when writing
> to SPR 0x3f2, so we are missing to lock the iothread in the code path
> here.
>
> Signed-off-by: Thomas Huth <thuth@redhat.com>

Reviewed-by: Cédric Le Goater <clg@kaod.org>
Tested-by: Cédric Le Goater <clg@kaod.org>

Thanks,

C.

> ---
>   hw/ppc/ppc.c | 4 ++++
>   1 file changed, 4 insertions(+)
>
> diff --git a/hw/ppc/ppc.c b/hw/ppc/ppc.c
> index f5d012f860..bb57f1c9ed 100644
> --- a/hw/ppc/ppc.c
> +++ b/hw/ppc/ppc.c
> @@ -336,6 +336,8 @@ void store_40x_dbcr0(CPUPPCState *env, uint32_t val)
>   {
>       PowerPCCPU *cpu = env_archcpu(env);
>   
> +    qemu_mutex_lock_iothread();
> +
>       switch ((val >> 28) & 0x3) {
>       case 0x0:
>           /* No action */
> @@ -353,6 +355,8 @@ void store_40x_dbcr0(CPUPPCState *env, uint32_t val)
>           ppc40x_system_reset(cpu);
>           break;
>       }
> +
> +    qemu_mutex_unlock_iothread();
>   }
>   
>   /* PowerPC 40x internal IRQ controller */