From mboxrd@z Thu Jan 1 00:00:00 1970 From: Benjamin Herrenschmidt Date: Mon, 20 Mar 2017 06:49:06 +0000 Subject: [PATCH 04/12] powerpc: Add optional smp_ops->prepare_cpu SMP callback Message-Id: <20170320064914.4437-4-benh@kernel.crashing.org> List-Id: References: <20170320064914.4437-1-benh@kernel.crashing.org> In-Reply-To: <20170320064914.4437-1-benh@kernel.crashing.org> MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: linuxppc-dev@ozlabs.org, kvm-ppc@vger.kernel.org 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 --- 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 32db16d..2f8e36f 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 46f89e6..b12f5f0 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 */ -- 2.9.3 From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from ozlabs.org (ozlabs.org [103.22.144.67]) (using TLSv1.2 with cipher ADH-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by lists.ozlabs.org (Postfix) with ESMTPS id 3vmmlh0QVyzDqYB for ; Mon, 20 Mar 2017 17:49:52 +1100 (AEDT) Received: from ozlabs.org (ozlabs.org [IPv6:2401:3900:2:1::2]) by bilbo.ozlabs.org (Postfix) with ESMTP id 3vmmlg71Zhz8wHb for ; Mon, 20 Mar 2017 17:49:51 +1100 (AEDT) Received: from gate.crashing.org (gate.crashing.org [63.228.1.57]) (using TLSv1 with cipher DHE-RSA-AES256-SHA (256/256 bits)) (No client certificate requested) by ozlabs.org (Postfix) with ESMTPS id 3vmmlg2Qx3z9s2s for ; Mon, 20 Mar 2017 17:49:51 +1100 (AEDT) From: Benjamin Herrenschmidt To: linuxppc-dev@ozlabs.org, kvm-ppc@vger.kernel.org Subject: [PATCH 04/12] powerpc: Add optional smp_ops->prepare_cpu SMP callback Date: Mon, 20 Mar 2017 17:49:06 +1100 Message-Id: <20170320064914.4437-4-benh@kernel.crashing.org> In-Reply-To: <20170320064914.4437-1-benh@kernel.crashing.org> References: <20170320064914.4437-1-benh@kernel.crashing.org> List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , 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 --- 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 32db16d..2f8e36f 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 46f89e6..b12f5f0 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 */ -- 2.9.3