From 90a9fc3eda18c298cbb3a3c65ac64e7f6b24e1f5 Mon Sep 17 00:00:00 2001
From: Wanpeng Li <wanpengli@tencent.com>
Date: Tue, 1 Jun 2021 22:18:40 +0800
Subject: [PATCH] cpuidle-haltpoll: Enable kvm guest polling when dedicated
physical CPUs are available
mainline inclusion
from mainline-5.4
commit 1328edca4a142ee3c7442d1eece2c3ca383eff35
category: feature
bugzilla: https://bugzilla.openeuler.org/show_bug.cgi?id=34
CVE: NA
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.
Signed-off-by: Wanpeng Li <wanpengli@tencent.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Signed-off-by: Yubo Miao <miaoyubo@huawei.com>
Signed-off-by: Xiangyou Xie <xiexiangyou@huawei.com>
Reviewed-by: Hailiang Zhang <zhang.zhanghailiang@huawei.com>
Reviewed-by: Hanjun Guo <guohanjun@huawei.com>
Signed-off-by: Yang Yingliang <yangyingliang@huawei.com>
Signed-off-by: Jiajun Chen <chenjiajun8@huawei.com>
Signed-off-by: Yang Yingliang <yangyingliang@huawei.com>
---
arch/x86/kernel/kvm.c | 1 +
drivers/cpuidle/cpuidle-haltpoll.c | 3 ++-
2 files changed, 3 insertions(+), 1 deletion(-)
diff --git a/arch/x86/kernel/kvm.c b/arch/x86/kernel/kvm.c
index cafd1a3faa04..9c52eec69bfc 100644
--- a/arch/x86/kernel/kvm.c
+++ b/arch/x86/kernel/kvm.c
@@ -703,6 +703,7 @@ 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 49a65c6fe91e..932390b028f1 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);
--
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