Mahesh J Salgaonkar <mah...@linux.vnet.ibm.com> writes:
> From: Mahesh Salgaonkar <mah...@linux.vnet.ibm.com>
>
> Recently we moved HMI handling into Linux kernel instead of taking
> HMI directly in OPAL. This new change is dependent on new OPAL call
> for HMI recovery which was introduced in newer firmware. While this new
> change works fine with latest OPAL firmware, we broke the HMI handling
> if we run newer kernel on old OPAL firmware that results in system hang.
>
> This patch fixes this issue by falling back to old HMI behavior on older
> OPAL firmware.
>
> This patch introduces a check for opal token OPAL_HANDLE_HMI to see
> if we are running on newer firmware or old firmware. On newer firmware
> this check would return OPAL_TOKEN_PRESENT, otherwise we are running on
> old firmware and fallback to old HMI behavior.
>
> This patch depends on opal check token patch posted at ppc-devel
> https://lists.ozlabs.org/pipermail/linuxppc-dev/2014-August/120224.html
(just reviewed that patch before this one...)
> diff --git a/arch/powerpc/platforms/powernv/opal.c
> b/arch/powerpc/platforms/powernv/opal.c
> index b44eec3..2768cd3 100644
> --- a/arch/powerpc/platforms/powernv/opal.c
> +++ b/arch/powerpc/platforms/powernv/opal.c
> @@ -194,6 +194,24 @@ static int __init opal_register_exception_handlers(void)
> * fwnmi area at 0x7000 to provide the glue space to OPAL
> */
> glue = 0x7000;
> +
> + /* Check if we are running on newer firmware that exports
> + * OPAL_HANDLE_HMI token. If yes, then don't ask opal to patch
> + * HMI interrupt and we catch it directly in Linux kernel.
> + *
> + * For older firmware we will fallback to old behavior and
> + * let OPAL patch the HMI vector and handle it inside OPAL
> + * firmware.
> + */
> + if (opal_check_token(OPAL_HANDLE_HMI) != OPAL_TOKEN_PRESENT) {
> + /* We are on old firmware. fallback to old behavior. */
> + pr_info("%s: Falling back to old HMI handling behavior.\n",
> + __func__);
> + opal_register_exception_handler(
> + OPAL_HYPERVISOR_MAINTENANCE_HANDLER,
> + 0, glue);
> + glue += 128;
> + }
> opal_register_exception_handler(OPAL_SOFTPATCH_HANDLER, 0,
> glue);
So.. that all looks fine, but another note: why are we doing the
OPAL_SOFTPATCH_HANDLER and why is it all #if 0 out in skiboot?
for this patch:
Reviewed-by: Stewart Smith <stew...@linux.vnet.ibm.com>
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