xen: implement CPU hotplugging
Note the changes from 2.6.18-xen CPU hotplugging:
A vcpu_down request from the remote admin via Xenbus both hotunplugs the
CPU, and disables it by removing it from the cpu_present map, and removing
its entry in /sys.
A vcpu_up request from the remote admin only re-enables the CPU, and does
not immediately bring the CPU up. A udev event is emitted, which can be
caught by the user if he wishes to automatically re-up CPUs when available,
or implement a more complex policy.
Signed-off-by: Alex Nixon <alex.nixon@citrix.com>
Acked-by: Jeremy Fitzhardinge <jeremy@goop.org>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
diff --git a/arch/x86/xen/smp.c b/arch/x86/xen/smp.c
index baca7f2..be5cbb2 100644
--- a/arch/x86/xen/smp.c
+++ b/arch/x86/xen/smp.c
@@ -11,8 +11,6 @@
* useful topology information for the kernel to make use of. As a
* result, all CPUs are treated as if they're single-core and
* single-threaded.
- *
- * This does not handle HOTPLUG_CPU yet.
*/
#include <linux/sched.h>
#include <linux/err.h>
@@ -61,11 +59,12 @@
return IRQ_HANDLED;
}
-static __cpuinit void cpu_bringup_and_idle(void)
+static __cpuinit void cpu_bringup(void)
{
int cpu = smp_processor_id();
cpu_init();
+ touch_softlockup_watchdog();
preempt_disable();
xen_enable_sysenter();
@@ -86,6 +85,11 @@
local_irq_enable();
wmb(); /* make sure everything is out */
+}
+
+static __cpuinit void cpu_bringup_and_idle(void)
+{
+ cpu_bringup();
cpu_idle();
}
@@ -209,8 +213,6 @@
cpu_set(cpu, cpu_present_map);
}
-
- //init_xenbus_allowed_cpumask();
}
static __cpuinit int
@@ -278,12 +280,6 @@
struct task_struct *idle = idle_task(cpu);
int rc;
-#if 0
- rc = cpu_up_check(cpu);
- if (rc)
- return rc;
-#endif
-
#ifdef CONFIG_X86_64
/* Allocate node local memory for AP pdas */
WARN_ON(cpu == 0);
@@ -336,6 +332,42 @@
{
}
+int xen_cpu_disable(void)
+{
+ unsigned int cpu = smp_processor_id();
+ if (cpu == 0)
+ return -EBUSY;
+
+ cpu_disable_common();
+
+ load_cr3(swapper_pg_dir);
+ return 0;
+}
+
+void xen_cpu_die(unsigned int cpu)
+{
+ while (HYPERVISOR_vcpu_op(VCPUOP_is_up, cpu, NULL)) {
+ current->state = TASK_UNINTERRUPTIBLE;
+ schedule_timeout(HZ/10);
+ }
+ unbind_from_irqhandler(per_cpu(resched_irq, cpu), NULL);
+ unbind_from_irqhandler(per_cpu(callfunc_irq, cpu), NULL);
+ unbind_from_irqhandler(per_cpu(debug_irq, cpu), NULL);
+ unbind_from_irqhandler(per_cpu(callfuncsingle_irq, cpu), NULL);
+ xen_uninit_lock_cpu(cpu);
+ xen_teardown_timer(cpu);
+
+ if (num_online_cpus() == 1)
+ alternatives_smp_switch(0);
+}
+
+void xen_play_dead(void)
+{
+ play_dead_common();
+ HYPERVISOR_vcpu_op(VCPUOP_down, smp_processor_id(), NULL);
+ cpu_bringup();
+}
+
static void stop_self(void *v)
{
int cpu = smp_processor_id();
@@ -419,9 +451,13 @@
static const struct smp_ops xen_smp_ops __initdata = {
.smp_prepare_boot_cpu = xen_smp_prepare_boot_cpu,
.smp_prepare_cpus = xen_smp_prepare_cpus,
- .cpu_up = xen_cpu_up,
.smp_cpus_done = xen_smp_cpus_done,
+ .cpu_up = xen_cpu_up,
+ .cpu_die = xen_cpu_die,
+ .cpu_disable = xen_cpu_disable,
+ .play_dead = xen_play_dead,
+
.smp_send_stop = xen_smp_send_stop,
.smp_send_reschedule = xen_smp_send_reschedule,