Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1757141AbcDEFLh (ORCPT ); Tue, 5 Apr 2016 01:11:37 -0400 Received: from mx2.suse.de ([195.135.220.15]:35230 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754583AbcDEFKZ (ORCPT ); Tue, 5 Apr 2016 01:10:25 -0400 From: Juergen Gross To: linux-kernel@vger.kernel.org, xen-devel@lists.xenproject.org Cc: boris.ostrovsky@oracle.com, david.vrabel@citrix.com, mingo@redhat.com, peterz@infradead.org, Douglas_Warzecha@dell.com, pali.rohar@gmail.com, jdelvare@suse.com, linux@roeck-us.net, tglx@linutronix.de, hpa@zytor.com, jeremy@goop.org, chrisw@sous-sol.org, akataria@vmware.com, rusty@rustcorp.com.au, virtualization@lists.linux-foundation.org, x86@kernel.org, Juergen Gross Subject: [PATCH v4 3/6] smp: add function to execute a function synchronously on a cpu Date: Tue, 5 Apr 2016 07:10:04 +0200 Message-Id: <1459833007-11618-4-git-send-email-jgross@suse.com> X-Mailer: git-send-email 2.6.2 In-Reply-To: <1459833007-11618-1-git-send-email-jgross@suse.com> References: <1459833007-11618-1-git-send-email-jgross@suse.com> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 3277 Lines: 116 On some hardware models (e.g. Dell Studio 1555 laptop) some hardware related functions (e.g. SMIs) are to be executed on physical cpu 0 only. Instead of open coding such a functionality multiple times in the kernel add a service function for this purpose. This will enable the possibility to take special measures in virtualized environments like Xen, too. Signed-off-by: Juergen Gross --- V4: change return value in case of illegal cpu as requested by Peter Zijlstra make pinning of vcpu an option as suggested by Peter Zijlstra V2: instead of manipulating the allowed set of cpus use cpu specific workqueue as requested by Peter Zijlstra --- include/linux/smp.h | 2 ++ kernel/smp.c | 50 ++++++++++++++++++++++++++++++++++++++++++++++++++ kernel/up.c | 17 +++++++++++++++++ 3 files changed, 69 insertions(+) diff --git a/include/linux/smp.h b/include/linux/smp.h index c441407..3b5813b 100644 --- a/include/linux/smp.h +++ b/include/linux/smp.h @@ -196,4 +196,6 @@ extern void arch_enable_nonboot_cpus_end(void); void smp_setup_processor_id(void); +int smp_call_on_cpu(unsigned int cpu, bool pin, int (*func)(void *), void *par); + #endif /* __LINUX_SMP_H */ diff --git a/kernel/smp.c b/kernel/smp.c index 9388064..357458b 100644 --- a/kernel/smp.c +++ b/kernel/smp.c @@ -740,3 +740,53 @@ void wake_up_all_idle_cpus(void) preempt_enable(); } EXPORT_SYMBOL_GPL(wake_up_all_idle_cpus); + +/** + * smp_call_on_cpu - Call a function on a specific cpu + * + * Used to call a function on a specific cpu and wait for it to return. + * Optionally make sure the call is done on a specified physical cpu via vcpu + * pinning in order to support virtualized environments. + */ +struct smp_call_on_cpu_struct { + struct work_struct work; + struct completion done; + int (*func)(void *); + void *data; + int ret; + int cpu; +}; + +static void smp_call_on_cpu_callback(struct work_struct *work) +{ + struct smp_call_on_cpu_struct *sscs; + + sscs = container_of(work, struct smp_call_on_cpu_struct, work); + if (sscs->cpu >= 0) + hypervisor_pin_vcpu(sscs->cpu); + sscs->ret = sscs->func(sscs->data); + if (sscs->cpu >= 0) + hypervisor_pin_vcpu(-1); + + complete(&sscs->done); +} + +int smp_call_on_cpu(unsigned int cpu, bool pin, int (*func)(void *), void *par) +{ + struct smp_call_on_cpu_struct sscs = { + .work = __WORK_INITIALIZER(sscs.work, smp_call_on_cpu_callback), + .done = COMPLETION_INITIALIZER_ONSTACK(sscs.done), + .func = func, + .data = par, + .cpu = pin ? cpu : -1, + }; + + if (cpu >= nr_cpu_ids) + return -ENXIO; + + queue_work_on(cpu, system_wq, &sscs.work); + wait_for_completion(&sscs.done); + + return sscs.ret; +} +EXPORT_SYMBOL_GPL(smp_call_on_cpu); diff --git a/kernel/up.c b/kernel/up.c index 3ccee2b..8266810b 100644 --- a/kernel/up.c +++ b/kernel/up.c @@ -83,3 +83,20 @@ void on_each_cpu_cond(bool (*cond_func)(int cpu, void *info), preempt_enable(); } EXPORT_SYMBOL(on_each_cpu_cond); + +int smp_call_on_cpu(unsigned int cpu, bool pin, int (*func)(void *), void *par) +{ + int ret; + + if (cpu != 0) + return -ENXIO; + + if (pin) + hypervisor_pin_vcpu(0); + ret = func(par); + if (pin) + hypervisor_pin_vcpu(-1); + + return ret; +} +EXPORT_SYMBOL_GPL(smp_call_on_cpu); -- 2.6.2