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: fa86ee90eb11 ("add cpuidle-haltpoll driver")
Signed-off-by: Joao Martins <joao.m.martins@oracle.com>
Signed-off-by: Boris Ostrovsky <boris.ostrovsky@oracle.com>
Reviewed-by: Marcelo Tosatti <mtosatti@redhat.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

diff --git a/arch/x86/include/asm/cpuidle_haltpoll.h b/arch/x86/include/asm/cpuidle_haltpoll.h
index ff8607d81526120e98db8e382463550426e3d470..c8b39c6716ff1798ab3e1391722e9b4f99aab2aa 100644 (file)
--- a/arch/x86/include/asm/cpuidle_haltpoll.h
+++ b/arch/x86/include/asm/cpuidle_haltpoll.h
@@ -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

diff --git a/arch/x86/kernel/kvm.c b/arch/x86/kernel/kvm.c
index f48401be8ce00a2bb29826e3464df6597ac48ad7..60bab4a3b36b1c0fa0947da1d29088bab896b5b0 100644 (file)
--- a/arch/x86/kernel/kvm.c
+++ b/arch/x86/kernel/kvm.c
@@ -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

diff --git a/drivers/cpuidle/cpuidle-haltpoll.c b/drivers/cpuidle/cpuidle-haltpoll.c
index 9ac093dcbb01f26593b9f989ee6b3faa619fc035..56d8ab814466f11f7834eb03fa1b922427d18da1 100644 (file)
--- a/drivers/cpuidle/cpuidle-haltpoll.c
+++ b/drivers/cpuidle/cpuidle-haltpoll.c
@@ -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);

diff --git a/include/linux/cpuidle_haltpoll.h b/include/linux/cpuidle_haltpoll.h
index fe5954c2409e6845b4665a04d0b50b855a0737fc..d50c1e0411a2dda2376ff01e34f01075ebe7a245 100644 (file)
--- a/include/linux/cpuidle_haltpoll.h
+++ b/include/linux/cpuidle_haltpoll.h
@@ -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