From 45b21cfeb22087795f0b49397fbe529efeb99baf Mon Sep 17 00:00:00 2001 From: Michael Ellerman Date: Wed, 26 Apr 2017 17:32:38 +1000 Subject: powerpc/powernv: Fix oops on P9 DD1 in cause_ipi() Recently we merged the native xive support for Power9, and then separately some reworks for doorbell IPI support. In isolation both series were OK, but the merged result had a bug in one case. On P9 DD1 we use pnv_p9_dd1_cause_ipi() which tries to use doorbells, and then falls back to the interrupt controller. However the fallback is implemented by calling icp_ops->cause_ipi. But now that xive support is merged we might be using xive, in which case icp_ops is not initialised, it's a xics specific structure. This leads to an oops such as: Unable to handle kernel paging request for data at address 0x00000028 Oops: Kernel access of bad area, sig: 11 [#1] NIP pnv_p9_dd1_cause_ipi+0x74/0xe0 LR smp_muxed_ipi_message_pass+0x54/0x70 To fix it, rather than using icp_ops which might be NULL, have both xics and xive set smp_ops->cause_ipi, and then in the powernv code we save that as ic_cause_ipi before overriding smp_ops->cause_ipi. For paranoia add a WARN_ON() to check if somehow smp_ops->cause_ipi is NULL. Fixes: b866cc2199d6 ("powerpc: Change the doorbell IPI calling convention") Tested-by: Gautham R. Shenoy Signed-off-by: Michael Ellerman --- arch/powerpc/sysdev/xics/xics-common.c | 3 +++ 1 file changed, 3 insertions(+) (limited to 'arch/powerpc/sysdev/xics') diff --git a/arch/powerpc/sysdev/xics/xics-common.c b/arch/powerpc/sysdev/xics/xics-common.c index 2eb53c1..ffe138b 100644 --- a/arch/powerpc/sysdev/xics/xics-common.c +++ b/arch/powerpc/sysdev/xics/xics-common.c @@ -145,6 +145,9 @@ void __init xics_smp_probe(void) { /* Register all the IPIs */ xics_request_ipi(); + + /* Setup cause_ipi callback based on which ICP is used */ + smp_ops->cause_ipi = icp_ops->cause_ipi; } #endif /* CONFIG_SMP */ -- cgit v1.1