[PATCH RFC v2 1/3] drivers/platform/x86: add cpu physically hotplug driver

From: liguang
Date: Wed Jun 05 2013 - 21:50:54 EST


this driver will support cpu phyical add/removal automatically
after online/offline. if cpu hotpluged, cpu will not
online automatically, and for cpu offline, we try to
do actually eject if allowed for cpu like
"echo 1 > /sys/bus/acpi/devices/LNXCPU\:0X/eject"
this "echo ..." is only present for recent kernel
(sorry, can't figure out since when), for a little
older kernel, there's not such approach AFAICS.

Signed-off-by: liguang <lig.fnst@xxxxxxxxxxxxxx>
---
drivers/platform/x86/Kconfig | 8 ++++
drivers/platform/x86/Makefile | 1 +
drivers/platform/x86/cpu_physic_hotplug.c | 60 +++++++++++++++++++++++++++++
3 files changed, 69 insertions(+), 0 deletions(-)
create mode 100644 drivers/platform/x86/cpu_physic_hotplug.c

diff --git a/drivers/platform/x86/Kconfig b/drivers/platform/x86/Kconfig
index 8577261..39b2392 100644
--- a/drivers/platform/x86/Kconfig
+++ b/drivers/platform/x86/Kconfig
@@ -789,4 +789,12 @@ config PVPANIC
a paravirtualized device provided by QEMU; it lets a virtual machine
(guest) communicate panic events to the host.

+config QEMU_CPU_PHYSIC_HOTPLUG
+ tristate "physically add/remove cpu after cpu onlined/offlined"
+ depends on ACPI_HOTPLUG_CPU
+ ---help---
+ This driver will support physically remove a cpu after
+ it offlined for QEMU automatically. someone may require this feature
+ to do a physically removal for a cpu.
+
endif # X86_PLATFORM_DEVICES
diff --git a/drivers/platform/x86/Makefile b/drivers/platform/x86/Makefile
index ef0ec74..2e669b0 100644
--- a/drivers/platform/x86/Makefile
+++ b/drivers/platform/x86/Makefile
@@ -53,3 +53,4 @@ obj-$(CONFIG_APPLE_GMUX) += apple-gmux.o
obj-$(CONFIG_CHROMEOS_LAPTOP) += chromeos_laptop.o

obj-$(CONFIG_PVPANIC) += pvpanic.o
+obj-$(CONFIG_QEMU_CPU_PHYSIC_HOTPLUG) += cpu_physic_hotplug.o
diff --git a/drivers/platform/x86/cpu_physic_hotplug.c b/drivers/platform/x86/cpu_physic_hotplug.c
new file mode 100644
index 0000000..a52c042
--- /dev/null
+++ b/drivers/platform/x86/cpu_physic_hotplug.c
@@ -0,0 +1,60 @@
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/acpi.h>
+#include <linux/cpu.h>
+#include <linux/notifier.h>
+#include <acpi/processor.h>
+
+MODULE_AUTHOR("Li Guang");
+MODULE_DESCRIPTION("CPU physically hot-plug/unplug Driver");
+MODULE_LICENSE("GPL");
+
+static int cpu_logic_hotplug_notify(struct notifier_block *nfb,
+ unsigned long action, void *hcpu)
+{
+ unsigned int cpu = (unsigned long)hcpu;
+ struct acpi_processor *pr = per_cpu(processors, cpu);
+
+ if (pr) {
+ switch (action) {
+ case CPU_ONLINE:
+ break;
+ case CPU_DEAD:
+ break;
+ default:
+ break;
+ }
+ }
+ return NOTIFY_OK;
+}
+
+static struct notifier_block cpu_logic_hotplug_notifier =
+{
+ .notifier_call = cpu_logic_hotplug_notify,
+};
+
+static int cpu_physic_hotplug_notify(struct notifier_block *nfb,
+ unsigned char *s)
+{
+}
+
+static struct notifier_block cpu_physic_hotplug_notifier =
+{
+ .notifier_call = cpu_physic_hotplug_notify,
+};
+
+static int __init cpu_qemu_hotplug_init(void)
+{
+ register_hotcpu_notifier(&cpu_logic_hotplug_notifier);
+ register_ec_gpe_notifier(&cpu_physic_hotplug_notifier);
+ return 0;
+}
+
+static void __exit cpu_qemu_hotplug_exit(void)
+{
+ unregister_hotcpu_notifier(&cpu_logic_hotplug_notifier);
+ unregister_ec_gpe_notifier(&cpu_physic_hotplug_notifier);
+}
+
+module_init(cpu_qemu_hotplug_init);
+module_exit(cpu_qemu_hotplug_exit);
--
1.7.2.5

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