Re: [PATCH] powerpc/powernv: Fallback to old HMI handling behavior for old firmware
flat view
From: Stewart Smith <hidden>
Date: 2014-10-07 04:53:17
Mahesh J Salgaonkar [off-list ref] writes:
From: Mahesh Salgaonkar <redacted> 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...)
quoted hunk ↗ jump to hunk
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 <redacted>