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Commit df8ce9d7 authored by Juergen Gross's avatar Juergen Gross Committed by Ingo Molnar
Browse files

smp: Add function to execute a function synchronously on a CPU 



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: default avatarJuergen Gross <jgross@suse.com>
Signed-off-by: default avatarPeter Zijlstra (Intel) <peterz@infradead.org>
Cc: Douglas_Warzecha@dell.com
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: akataria@vmware.com
Cc: boris.ostrovsky@oracle.com
Cc: chrisw@sous-sol.org
Cc: david.vrabel@citrix.com
Cc: hpa@zytor.com
Cc: jdelvare@suse.com
Cc: jeremy@goop.org
Cc: linux@roeck-us.net
Cc: pali.rohar@gmail.com
Cc: rusty@rustcorp.com.au
Cc: virtualization@lists.linux-foundation.org
Cc: xen-devel@lists.xenproject.org
Link: http://lkml.kernel.org/r/1472453327-19050-4-git-send-email-jgross@suse.com


Signed-off-by: default avatarIngo Molnar <mingo@kernel.org>
parent 47ae4b05

include/linux/smp.h

+3 −0
Original line number Diff line number Diff line
@@ -196,6 +196,9 @@ 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);



/* SMP core functions */

int smpcfd_prepare_cpu(unsigned int cpu);

int smpcfd_dead_cpu(unsigned int cpu);

kernel/smp.c

+50 −0
Original line number Diff line number Diff line
@@ -725,3 +725,53 @@ 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);

kernel/up.c

+17 −0
Original line number Diff line number Diff line
@@ -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);