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From: Juergen Gross <jgross@suse.com>
To: linux-kernel@vger.kernel.org, xen-devel@lists.xenproject.org
Cc: Juergen Gross <jgross@suse.com>,
	jeremy@goop.org, jdelvare@suse.com, peterz@infradead.org,
	hpa@zytor.com, akataria@vmware.com, x86@kernel.org,
	rusty@rustcorp.com.au, virtualization@lists.linux-foundation.org,
	chrisw@sous-sol.org, mingo@redhat.com, david.vrabel@citrix.com,
	Douglas_Warzecha@dell.com, pali.rohar@gmail.com,
	boris.ostrovsky@oracle.com, tglx@linutronix.de,
	linux@roeck-us.net
Subject: [PATCH v5 3/6] smp: add function to execute a function synchronously on a cpu
Date: Wed,  6 Apr 2016 16:17:43 +0200	[thread overview]
Message-ID: <1459952266-3687-4-git-send-email-jgross__44468.7182004147$1459952350$gmane$org@suse.com> (raw)
In-Reply-To: <1459952266-3687-1-git-send-email-jgross@suse.com>

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 <jgross@suse.com>
---
V5: rename and reshuffle parameters of smp_call_on_cpu() as requested by
    Peter Zijlstra
    test target cpu to be online as requested by Peter Zijlstra

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 |  3 +++
 kernel/smp.c        | 50 ++++++++++++++++++++++++++++++++++++++++++++++++++
 kernel/up.c         | 17 +++++++++++++++++
 3 files changed, 70 insertions(+)

diff --git a/include/linux/smp.h b/include/linux/smp.h
index c441407..4f1c475 100644
--- a/include/linux/smp.h
+++ b/include/linux/smp.h
@@ -196,4 +196,7 @@ extern void arch_enable_nonboot_cpus_end(void);
 
 void smp_setup_processor_id(void);
 
+int smp_call_on_cpu(unsigned int cpu, int (*func)(void *), void *par,
+		    bool phys);
+
 #endif /* __LINUX_SMP_H */
diff --git a/kernel/smp.c b/kernel/smp.c
index 9388064..f671948 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, int (*func)(void *), void *par, bool phys)
+{
+	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  = phys ? cpu : -1,
+	};
+
+	if (cpu >= nr_cpu_ids || !cpu_online(cpu))
+		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..ee81ac9 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, int (*func)(void *), void *par, bool phys)
+{
+	int ret;
+
+	if (cpu != 0)
+		return -ENXIO;
+
+	if (phys)
+		hypervisor_pin_vcpu(0);
+	ret = func(par);
+	if (phys)
+		hypervisor_pin_vcpu(-1);
+
+	return ret;
+}
+EXPORT_SYMBOL_GPL(smp_call_on_cpu);
-- 
2.6.6


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  parent reply	other threads:[~2016-04-06 14:17 UTC|newest]

Thread overview: 14+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
     [not found] <1459952266-3687-1-git-send-email-jgross@suse.com>
2016-04-06 14:17 ` [PATCH v5 1/6] xen: sync xen header Juergen Gross
2016-04-06 14:17 ` [PATCH v5 2/6] virt, sched: add generic vcpu pinning support Juergen Gross
2016-04-06 14:17 ` Juergen Gross [this message]
2016-04-06 14:17 ` [PATCH v5 4/6] xen: add xen_pin_vcpu() to support calling functions on a dedicated pcpu Juergen Gross
2016-04-06 14:17 ` [PATCH v5 5/6] dcdbas: make use of smp_call_on_cpu() Juergen Gross
2016-04-06 14:17 ` [PATCH v5 6/6] hwmon: use smp_call_on_cpu() for dell-smm i8k Juergen Gross
     [not found] ` <1459952266-3687-4-git-send-email-jgross@suse.com>
2016-04-06 18:04   ` [PATCH v5 3/6] smp: add function to execute a function synchronously on a cpu Peter Zijlstra
2016-04-13  8:49 ` [PATCH v5 0/6] Support calling functions on dedicated physical cpu Juergen Gross
     [not found] ` <570E07FD.4030403@suse.com>
2016-05-17 11:21   ` Juergen Gross
     [not found] ` <1459952266-3687-7-git-send-email-jgross@suse.com>
2016-06-13 19:05   ` [PATCH v5 6/6] hwmon: use smp_call_on_cpu() for dell-smm i8k Pali Rohár
     [not found] ` <1459952266-3687-3-git-send-email-jgross@suse.com>
2016-06-15 11:18   ` [PATCH v5 2/6] virt, sched: add generic vcpu pinning support Juergen Gross
     [not found] ` <1459952266-3687-6-git-send-email-jgross@suse.com>
2016-06-15 11:19   ` [PATCH v5 5/6] dcdbas: make use of smp_call_on_cpu() Juergen Gross
2016-06-20  8:40 ` [PATCH v5 0/6] Support calling functions on dedicated physical cpu Juergen Gross
2016-06-27 10:34 ` Juergen Gross

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