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Message-Id: <20190902104031.9296-1-joao.m.martins@oracle.com>
Date: Mon, 2 Sep 2019 11:40:31 +0100
From: Joao Martins <joao.m.martins@...cle.com>
To: kvm@...r.kernel.org
Cc: Joao Martins <joao.m.martins@...cle.com>,
Marcelo Tosatti <mtosatti@...hat.com>,
linux-kernel@...r.kernel.org, Paolo Bonzini <pbonzini@...hat.com>,
Radim Krčmář <rkrcmar@...hat.com>,
Sean Christopherson <sean.j.christopherson@...el.com>,
Vitaly Kuznetsov <vkuznets@...hat.com>,
Wanpeng Li <wanpengli@...cent.com>,
Jim Mattson <jmattson@...gle.com>,
Joerg Roedel <joro@...tes.org>,
"Rafael J. Wysocki" <rjw@...ysocki.net>,
Daniel Lezcano <daniel.lezcano@...aro.org>,
linux-pm@...r.kernel.org,
Boris Ostrovsky <boris.ostrovsky@...cle.com>
Subject: [PATCH v3] 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@...cle.com>
Signed-off-by: Boris Ostrovsky <boris.ostrovsky@...cle.com>
---
v3:
* register the teardown callback for correct handling of hotunplug
and error cases. In case cpuhp_setup_state calls fails (e.g. in one of
the cpus that it invoked the callback) it will then call the teardown of
the previously enabled devices; so no need to handle that manually in
haltpoll_uninit().
* use the cpuhp_setup_state() returned dyn allocated state when it
succeeds. And use that state in haltpoll_unint() to call
cpuhp_remove_state() instead of looping online cpus manually. This
is because cpuhp_remove_state() invokes the teardown/offline callback.
* fix subsystem name to 'cpuidle' instead of 'idle' in cpuhp_setup_state()
v2:
* move cpus_read_unlock() after unregistering all cpuidle_devices;
(Marcello Tosatti)
* redundant usage of cpuidle_unregister() when only
cpuidle_unregister_driver() suffices; (Marcelo Tosatti)
* cpuhp_setup_state() returns a state (> 0) for CPUHP_AP_ONLINE_DYN
---
arch/x86/include/asm/cpuidle_haltpoll.h | 4 +-
arch/x86/kernel/kvm.c | 18 +++----
drivers/cpuidle/cpuidle-haltpoll.c | 68 +++++++++++++++++++++++--
include/linux/cpuidle_haltpoll.h | 4 +-
4 files changed, 73 insertions(+), 21 deletions(-)
diff --git a/arch/x86/include/asm/cpuidle_haltpoll.h b/arch/x86/include/asm/cpuidle_haltpoll.h
index ff8607d81526..c8b39c6716ff 100644
--- 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 8d150e3732d9..a9b6c4e2446d 100644
--- a/arch/x86/kernel/kvm.c
+++ b/arch/x86/kernel/kvm.c
@@ -880,32 +880,26 @@ 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 9ac093dcbb01..56d8ab814466 100644
--- 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 fe5954c2409e..d50c1e0411a2 100644
--- 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
--
2.17.1
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