Commit 97d3eb9d authored by Joao Martins's avatar Joao Martins Committed by Rafael J. Wysocki
Browse files

cpuidle-haltpoll: vcpu hotplug support 



When cpus != maxcpus cpuidle-haltpoll will fail to register all vcpus
past the online ones and thus fail to register the idle driver.
This is because cpuidle_add_sysfs() will return with -ENODEV as a
consequence from get_cpu_device() return no device for a non-existing
CPU.

Instead switch to cpuidle_register_driver() and manually register each
of the present cpus through cpuhp_setup_state() callbacks and future
ones that get onlined or offlined. This mimmics similar logic that
intel_idle does.

Fixes: fa86ee90 ("add cpuidle-haltpoll driver")
Signed-off-by: default avatarJoao Martins <joao.m.martins@oracle.com>
Signed-off-by: default avatarBoris Ostrovsky <boris.ostrovsky@oracle.com>
Reviewed-by: default avatarMarcelo Tosatti <mtosatti@redhat.com>
Signed-off-by: default avatarRafael J. Wysocki <rafael.j.wysocki@intel.com>
parent b7e7fffd

arch/x86/include/asm/cpuidle_haltpoll.h

+2 −2
Original line number Diff line number Diff line
@@ -2,7 +2,7 @@ 
#ifndef _ARCH_HALTPOLL_H

#define _ARCH_HALTPOLL_H



void arch_haltpoll_enable(void);

void arch_haltpoll_disable(void);

void arch_haltpoll_enable(unsigned int cpu);

void arch_haltpoll_disable(unsigned int cpu);



#endif

arch/x86/kernel/kvm.c

+6 −12
Original line number Diff line number Diff line
@@ -888,32 +888,26 @@ static void kvm_enable_host_haltpoll(void *i) 
	wrmsrl(MSR_KVM_POLL_CONTROL, 1);

}



void arch_haltpoll_enable(void)

void arch_haltpoll_enable(unsigned int cpu)

{

	if (!kvm_para_has_feature(KVM_FEATURE_POLL_CONTROL)) {

		printk(KERN_ERR "kvm: host does not support poll control\n");

		printk(KERN_ERR "kvm: host upgrade recommended\n");

		pr_err_once("kvm: host does not support poll control\n");

		pr_err_once("kvm: host upgrade recommended\n");

		return;

	}



	preempt_disable();

	/* Enable guest halt poll disables host halt poll */

	kvm_disable_host_haltpoll(NULL);

	smp_call_function(kvm_disable_host_haltpoll, NULL, 1);

	preempt_enable();

	smp_call_function_single(cpu, kvm_disable_host_haltpoll, NULL, 1);

}

EXPORT_SYMBOL_GPL(arch_haltpoll_enable);



void arch_haltpoll_disable(void)

void arch_haltpoll_disable(unsigned int cpu)

{

	if (!kvm_para_has_feature(KVM_FEATURE_POLL_CONTROL))

		return;



	preempt_disable();

	/* Enable guest halt poll disables host halt poll */

	kvm_enable_host_haltpoll(NULL);

	smp_call_function(kvm_enable_host_haltpoll, NULL, 1);

	preempt_enable();

	smp_call_function_single(cpu, kvm_enable_host_haltpoll, NULL, 1);

}

EXPORT_SYMBOL_GPL(arch_haltpoll_disable);

#endif

drivers/cpuidle/cpuidle-haltpoll.c

+63 −5
Original line number Diff line number Diff line
@@ -11,12 +11,16 @@ 
 */



#include <linux/init.h>

#include <linux/cpu.h>

#include <linux/cpuidle.h>

#include <linux/module.h>

#include <linux/sched/idle.h>

#include <linux/kvm_para.h>

#include <linux/cpuidle_haltpoll.h>



static struct cpuidle_device __percpu *haltpoll_cpuidle_devices;

static enum cpuhp_state haltpoll_hp_state;



static int default_enter_idle(struct cpuidle_device *dev,

			      struct cpuidle_driver *drv, int index)

{
@@ -46,6 +50,46 @@ static struct cpuidle_driver haltpoll_driver = { 
	.state_count = 2,

};



static int haltpoll_cpu_online(unsigned int cpu)

{

	struct cpuidle_device *dev;



	dev = per_cpu_ptr(haltpoll_cpuidle_devices, cpu);

	if (!dev->registered) {

		dev->cpu = cpu;

		if (cpuidle_register_device(dev)) {

			pr_notice("cpuidle_register_device %d failed!\n", cpu);

			return -EIO;

		}

		arch_haltpoll_enable(cpu);

	}



	return 0;

}



static int haltpoll_cpu_offline(unsigned int cpu)

{

	struct cpuidle_device *dev;



	dev = per_cpu_ptr(haltpoll_cpuidle_devices, cpu);

	if (dev->registered) {

		arch_haltpoll_disable(cpu);

		cpuidle_unregister_device(dev);

	}



	return 0;

}



static void haltpoll_uninit(void)

{

	if (haltpoll_hp_state)

		cpuhp_remove_state(haltpoll_hp_state);

	cpuidle_unregister_driver(&haltpoll_driver);



	free_percpu(haltpoll_cpuidle_devices);

	haltpoll_cpuidle_devices = NULL;

}



static int __init haltpoll_init(void)

{

	int ret;
@@ -56,17 +100,31 @@ static int __init haltpoll_init(void) 
	if (!kvm_para_available())

		return 0;



	ret = cpuidle_register(&haltpoll_driver, NULL);

	if (ret == 0)

		arch_haltpoll_enable();

	ret = cpuidle_register_driver(drv);

	if (ret < 0)

		return ret;



	haltpoll_cpuidle_devices = alloc_percpu(struct cpuidle_device);

	if (haltpoll_cpuidle_devices == NULL) {

		cpuidle_unregister_driver(drv);

		return -ENOMEM;

	}



	ret = cpuhp_setup_state(CPUHP_AP_ONLINE_DYN, "cpuidle/haltpoll:online",

				haltpoll_cpu_online, haltpoll_cpu_offline);

	if (ret < 0) {

		haltpoll_uninit();

	} else {

		haltpoll_hp_state = ret;

		ret = 0;

	}



	return ret;

}



static void __exit haltpoll_exit(void)

{

	arch_haltpoll_disable();

	cpuidle_unregister(&haltpoll_driver);

	haltpoll_uninit();

}



module_init(haltpoll_init);

include/linux/cpuidle_haltpoll.h

+2 −2
Original line number Diff line number Diff line
@@ -5,11 +5,11 @@ 
#ifdef CONFIG_ARCH_CPUIDLE_HALTPOLL

#include <asm/cpuidle_haltpoll.h>

#else

static inline void arch_haltpoll_enable(void)

static inline void arch_haltpoll_enable(unsigned int cpu)

{

}



static inline void arch_haltpoll_disable(void)

static inline void arch_haltpoll_disable(unsigned int cpu)

{

}

#endif

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