add cpuidle-haltpoll driver

Add a cpuidle driver that calls the architecture default_idle routine.

To be used in conjunction with the haltpoll governor.

Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

diff --git a/arch/x86/kernel/process.c b/arch/x86/kernel/process.c
index 75fea0d..5e94c43 100644 (file)
--- a/arch/x86/kernel/process.c
+++ b/arch/x86/kernel/process.c
@@ -580,7 +580,7 @@ void __cpuidle default_idle(void)
        safe_halt();
        trace_cpu_idle_rcuidle(PWR_EVENT_EXIT, smp_processor_id());
 }
-#ifdef CONFIG_APM_MODULE
+#if defined(CONFIG_APM_MODULE) || defined(CONFIG_HALTPOLL_CPUIDLE_MODULE)
 EXPORT_SYMBOL(default_idle);
 #endif
 

diff --git a/drivers/cpuidle/Kconfig b/drivers/cpuidle/Kconfig
index a4ac31e..cc8efc5 100644 (file)
--- a/drivers/cpuidle/Kconfig
+++ b/drivers/cpuidle/Kconfig
@@ -51,6 +51,15 @@ depends on PPC
 source "drivers/cpuidle/Kconfig.powerpc"
 endmenu
 
+config HALTPOLL_CPUIDLE
+       tristate "Halt poll cpuidle driver"
+       depends on X86 && KVM_GUEST
+       default y
+       help
+         This option enables halt poll cpuidle driver, which allows to poll
+         before halting in the guest (more efficient than polling in the
+         host via halt_poll_ns for some scenarios).
+
 endif
 
 config ARCH_NEEDS_CPU_IDLE_COUPLED

diff --git a/drivers/cpuidle/Makefile b/drivers/cpuidle/Makefile
index 9d7176c..2402274 100644 (file)
--- a/drivers/cpuidle/Makefile
+++ b/drivers/cpuidle/Makefile
@@ -7,6 +7,7 @@ obj-y += cpuidle.o driver.o governor.o sysfs.o governors/
 obj-$(CONFIG_ARCH_NEEDS_CPU_IDLE_COUPLED) += coupled.o
 obj-$(CONFIG_DT_IDLE_STATES)             += dt_idle_states.o
 obj-$(CONFIG_ARCH_HAS_CPU_RELAX)         += poll_state.o
+obj-$(CONFIG_HALTPOLL_CPUIDLE)           += cpuidle-haltpoll.o
 
 ##################################################################################
 # ARM SoC drivers

diff --git a/drivers/cpuidle/cpuidle-haltpoll.c b/drivers/cpuidle/cpuidle-haltpoll.c
new file mode 100644 (file)
index 0000000..35cfb53
--- /dev/null
+++ b/drivers/cpuidle/cpuidle-haltpoll.c
@@ -0,0 +1,68 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * cpuidle driver for haltpoll governor.
+ *
+ * Copyright 2019 Red Hat, Inc. and/or its affiliates.
+ *
+ * This work is licensed under the terms of the GNU GPL, version 2.  See
+ * the COPYING file in the top-level directory.
+ *
+ * Authors: Marcelo Tosatti <mtosatti@redhat.com>
+ */
+
+#include <linux/init.h>
+#include <linux/cpuidle.h>
+#include <linux/module.h>
+#include <linux/sched/idle.h>
+#include <linux/kvm_para.h>
+
+static int default_enter_idle(struct cpuidle_device *dev,
+                             struct cpuidle_driver *drv, int index)
+{
+       if (current_clr_polling_and_test()) {
+               local_irq_enable();
+               return index;
+       }
+       default_idle();
+       return index;
+}
+
+static struct cpuidle_driver haltpoll_driver = {
+       .name = "haltpoll",
+       .owner = THIS_MODULE,
+       .states = {
+               { /* entry 0 is for polling */ },
+               {
+                       .enter                  = default_enter_idle,
+                       .exit_latency           = 1,
+                       .target_residency       = 1,
+                       .power_usage            = -1,
+                       .name                   = "haltpoll idle",
+                       .desc                   = "default architecture idle",
+               },
+       },
+       .safe_state_index = 0,
+       .state_count = 2,
+};
+
+static int __init haltpoll_init(void)
+{
+       struct cpuidle_driver *drv = &haltpoll_driver;
+
+       cpuidle_poll_state_init(drv);
+
+       if (!kvm_para_available())
+               return 0;
+
+       return cpuidle_register(&haltpoll_driver, NULL);
+}
+
+static void __exit haltpoll_exit(void)
+{
+       cpuidle_unregister(&haltpoll_driver);
+}
+
+module_init(haltpoll_init);
+module_exit(haltpoll_exit);
+MODULE_LICENSE("GPL");
+MODULE_AUTHOR("Marcelo Tosatti <mtosatti@redhat.com>");