From 14d4ae5c4cb89c05262fe41cb7a26f6ba949d8df Mon Sep 17 00:00:00 2001 From: Benjamin Herrenschmidt Date: Wed, 5 Apr 2017 17:54:48 +1000 Subject: [PATCH] powerpc: Add optional smp_ops->prepare_cpu SMP callback Some platforms (will) need to perform allocations before bringing a new CPU online. Doing it from smp_ops->setup_cpu is the wrong thing to do: - It has no useful failure path (too late) - Calling any allocator will enable interrupts prematurely causing problems with large decrementer among others Instead, add a new callback that is called from __cpu_up (so from the context trying to online the new CPU) at a point where we can safely allocate and handle failures. This will be used by XIVE support. Signed-off-by: Benjamin Herrenschmidt Signed-off-by: Michael Ellerman --- arch/powerpc/include/asm/smp.h | 1 + arch/powerpc/kernel/smp.c | 10 ++++++++++ 2 files changed, 11 insertions(+) diff --git a/arch/powerpc/include/asm/smp.h b/arch/powerpc/include/asm/smp.h index 32db16d2e7ad..2f8e36f91acd 100644 --- a/arch/powerpc/include/asm/smp.h +++ b/arch/powerpc/include/asm/smp.h @@ -44,6 +44,7 @@ struct smp_ops_t { #endif void (*probe)(void); int (*kick_cpu)(int nr); + int (*prepare_cpu)(int nr); void (*setup_cpu)(int nr); void (*bringup_done)(void); void (*take_timebase)(void); diff --git a/arch/powerpc/kernel/smp.c b/arch/powerpc/kernel/smp.c index 46f89e66a273..b12f5f0a408f 100644 --- a/arch/powerpc/kernel/smp.c +++ b/arch/powerpc/kernel/smp.c @@ -521,6 +521,16 @@ int __cpu_up(unsigned int cpu, struct task_struct *tidle) cpu_idle_thread_init(cpu, tidle); + /* + * The platform might need to allocate resources prior to bringing + * up the CPU + */ + if (smp_ops->prepare_cpu) { + rc = smp_ops->prepare_cpu(cpu); + if (rc) + return rc; + } + /* Make sure callin-map entry is 0 (can be leftover a CPU * hotplug */ -- 2.20.1