From: Wanpeng Li Date: Thu, 29 Aug 2019 08:49:57 +0000 (+0800) Subject: cpuidle-haltpoll: Enable kvm guest polling when dedicated physical CPUs are available X-Git-Url: http://git.maquefel.me/?a=commitdiff_plain;h=1328edca4a14;p=linux.git cpuidle-haltpoll: Enable kvm guest polling when dedicated physical CPUs are available The downside of guest side polling is that polling is performed even with other runnable tasks in the host. However, even if poll in kvm can aware whether or not other runnable tasks in the same pCPU, it can still incur extra overhead in over-subscribe scenario. Now we can just enable guest polling when dedicated pCPUs are available. Acked-by: Paolo Bonzini Signed-off-by: Wanpeng Li Signed-off-by: Rafael J. Wysocki --- diff --git a/arch/x86/kernel/kvm.c b/arch/x86/kernel/kvm.c index 60bab4a3b36b1..3726ba48f763b 100644 --- a/arch/x86/kernel/kvm.c +++ b/arch/x86/kernel/kvm.c @@ -711,6 +711,7 @@ unsigned int kvm_arch_para_hints(void) { return cpuid_edx(kvm_cpuid_base() | KVM_CPUID_FEATURES); } +EXPORT_SYMBOL_GPL(kvm_arch_para_hints); static uint32_t __init kvm_detect(void) { diff --git a/drivers/cpuidle/cpuidle-haltpoll.c b/drivers/cpuidle/cpuidle-haltpoll.c index 49a65c6fe91e3..932390b028f1d 100644 --- a/drivers/cpuidle/cpuidle-haltpoll.c +++ b/drivers/cpuidle/cpuidle-haltpoll.c @@ -97,7 +97,8 @@ static int __init haltpoll_init(void) cpuidle_poll_state_init(drv); - if (!kvm_para_available()) + if (!kvm_para_available() || + !kvm_para_has_hint(KVM_HINTS_REALTIME)) return -ENODEV; ret = cpuidle_register_driver(drv);