From a1c4423b02b2121108e3ea9580741e0f26309a48 Mon Sep 17 00:00:00 2001 From: Marcelo Tosatti Date: Wed, 3 Jul 2019 20:51:29 -0300 Subject: [PATCH] cpuidle-haltpoll: disable host side polling when kvm virtualized When performing guest side polling, it is not necessary to also perform host side polling. So disable host side polling, via the new MSR interface, when loading cpuidle-haltpoll driver. Signed-off-by: Marcelo Tosatti Signed-off-by: Rafael J. Wysocki --- arch/x86/Kconfig | 7 +++++ arch/x86/include/asm/cpuidle_haltpoll.h | 8 +++++ arch/x86/kernel/kvm.c | 42 +++++++++++++++++++++++++ drivers/cpuidle/cpuidle-haltpoll.c | 9 +++++- include/linux/cpuidle_haltpoll.h | 16 ++++++++++ 5 files changed, 81 insertions(+), 1 deletion(-) create mode 100644 arch/x86/include/asm/cpuidle_haltpoll.h create mode 100644 include/linux/cpuidle_haltpoll.h diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig index 222855cc01584..05e78acb187c7 100644 --- a/arch/x86/Kconfig +++ b/arch/x86/Kconfig @@ -794,6 +794,7 @@ config KVM_GUEST bool "KVM Guest support (including kvmclock)" depends on PARAVIRT select PARAVIRT_CLOCK + select ARCH_CPUIDLE_HALTPOLL default y ---help--- This option enables various optimizations for running under the KVM @@ -802,6 +803,12 @@ config KVM_GUEST underlying device model, the host provides the guest with timing infrastructure such as time of day, and system time +config ARCH_CPUIDLE_HALTPOLL + def_bool n + prompt "Disable host haltpoll when loading haltpoll driver" + help + If virtualized under KVM, disable host haltpoll. + config PVH bool "Support for running PVH guests" ---help--- diff --git a/arch/x86/include/asm/cpuidle_haltpoll.h b/arch/x86/include/asm/cpuidle_haltpoll.h new file mode 100644 index 0000000000000..ff8607d815261 --- /dev/null +++ b/arch/x86/include/asm/cpuidle_haltpoll.h @@ -0,0 +1,8 @@ +/* SPDX-License-Identifier: GPL-2.0 */ +#ifndef _ARCH_HALTPOLL_H +#define _ARCH_HALTPOLL_H + +void arch_haltpoll_enable(void); +void arch_haltpoll_disable(void); + +#endif diff --git a/arch/x86/kernel/kvm.c b/arch/x86/kernel/kvm.c index b7f34fe2171e4..f48401be8ce00 100644 --- a/arch/x86/kernel/kvm.c +++ b/arch/x86/kernel/kvm.c @@ -875,3 +875,45 @@ void __init kvm_spinlock_init(void) } #endif /* CONFIG_PARAVIRT_SPINLOCKS */ + +#ifdef CONFIG_ARCH_CPUIDLE_HALTPOLL + +static void kvm_disable_host_haltpoll(void *i) +{ + wrmsrl(MSR_KVM_POLL_CONTROL, 0); +} + +static void kvm_enable_host_haltpoll(void *i) +{ + wrmsrl(MSR_KVM_POLL_CONTROL, 1); +} + +void arch_haltpoll_enable(void) +{ + 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"); + 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(); +} +EXPORT_SYMBOL_GPL(arch_haltpoll_enable); + +void arch_haltpoll_disable(void) +{ + 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(); +} +EXPORT_SYMBOL_GPL(arch_haltpoll_disable); +#endif diff --git a/drivers/cpuidle/cpuidle-haltpoll.c b/drivers/cpuidle/cpuidle-haltpoll.c index 35cfb53e92870..9ac093dcbb01f 100644 --- a/drivers/cpuidle/cpuidle-haltpoll.c +++ b/drivers/cpuidle/cpuidle-haltpoll.c @@ -15,6 +15,7 @@ #include #include #include +#include static int default_enter_idle(struct cpuidle_device *dev, struct cpuidle_driver *drv, int index) @@ -47,6 +48,7 @@ static struct cpuidle_driver haltpoll_driver = { static int __init haltpoll_init(void) { + int ret; struct cpuidle_driver *drv = &haltpoll_driver; cpuidle_poll_state_init(drv); @@ -54,11 +56,16 @@ static int __init haltpoll_init(void) if (!kvm_para_available()) return 0; - return cpuidle_register(&haltpoll_driver, NULL); + ret = cpuidle_register(&haltpoll_driver, NULL); + if (ret == 0) + arch_haltpoll_enable(); + + return ret; } static void __exit haltpoll_exit(void) { + arch_haltpoll_disable(); cpuidle_unregister(&haltpoll_driver); } diff --git a/include/linux/cpuidle_haltpoll.h b/include/linux/cpuidle_haltpoll.h new file mode 100644 index 0000000000000..fe5954c2409e6 --- /dev/null +++ b/include/linux/cpuidle_haltpoll.h @@ -0,0 +1,16 @@ +/* SPDX-License-Identifier: GPL-2.0 */ +#ifndef _CPUIDLE_HALTPOLL_H +#define _CPUIDLE_HALTPOLL_H + +#ifdef CONFIG_ARCH_CPUIDLE_HALTPOLL +#include +#else +static inline void arch_haltpoll_enable(void) +{ +} + +static inline void arch_haltpoll_disable(void) +{ +} +#endif +#endif -- 2.30.2