On Mon, Jan 28, 2019 at 10:46:21AM +0100, Cédric Le Goater wrote: > From: Benjamin Herrenschmidt <b...@kernel.crashing.org> > > It's very easy for the CPU specific has_work() implementation > and the logic in ppc_hw_interrupt() to be subtly out of sync. > > This can occasionally allow a CPU to wakeup from a PM state > and resume executing past the PM instruction when it should > resume at the 0x100 vector. > > This detects if it happens and aborts, making it a lot easier > to catch such bugs when testing rather than chasing obscure > guest misbehaviour. > > Signed-off-by: Benjamin Herrenschmidt <b...@kernel.crashing.org> > Signed-off-by: Cédric Le Goater <c...@kaod.org>
Reviewed-by: David Gibson <da...@gibson.dropbear.id.au>
> ---
> target/ppc/excp_helper.c | 16 ++++++++++++++++
> 1 file changed, 16 insertions(+)
>
> diff --git a/target/ppc/excp_helper.c b/target/ppc/excp_helper.c
> index 37546bb0f0fe..1a2f469a5fa2 100644
> --- a/target/ppc/excp_helper.c
> +++ b/target/ppc/excp_helper.c
> @@ -878,6 +878,22 @@ static void ppc_hw_interrupt(CPUPPCState *env)
> return;
> }
> }
> +
> + if (env->resume_as_sreset) {
> + /*
> + * This is a bug ! It means that has_work took us out of halt without
> + * anything to deliver while in a PM state that requires getting
> + * out via a 0x100
> + *
> + * This means we will incorrectly execute past the power management
> + * instruction instead of triggering a reset.
> + *
> + * It generally means a discrepancy between the wakup conditions in
> the
> + * processor has_work implementation and the logic in this function.
> + */
> + cpu_abort(CPU(ppc_env_get_cpu(env)),
> + "Wakeup from PM state but interrupt Undelivered");
> + }
> }
>
> void ppc_cpu_do_system_reset(CPUState *cs)
--
David Gibson | I'll have my music baroque, and my code
david AT gibson.dropbear.id.au | minimalist, thank you. NOT _the_ _other_
| _way_ _around_!
http://www.ozlabs.org/~dgibson
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