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path: root/drivers/kvm/kvm_main.c
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Diffstat (limited to 'drivers/kvm/kvm_main.c')
-rw-r--r--drivers/kvm/kvm_main.c64
1 files changed, 64 insertions, 0 deletions
diff --git a/drivers/kvm/kvm_main.c b/drivers/kvm/kvm_main.c
index a6cd1c1fe29..291d298868f 100644
--- a/drivers/kvm/kvm_main.c
+++ b/drivers/kvm/kvm_main.c
@@ -34,6 +34,7 @@
#include <linux/highmem.h>
#include <linux/file.h>
#include <asm/desc.h>
+#include <linux/cpu.h>
#include "x86_emulate.h"
#include "segment_descriptor.h"
@@ -2039,6 +2040,64 @@ static struct notifier_block kvm_reboot_notifier = {
.priority = 0,
};
+/*
+ * Make sure that a cpu that is being hot-unplugged does not have any vcpus
+ * cached on it.
+ */
+static void decache_vcpus_on_cpu(int cpu)
+{
+ struct kvm *vm;
+ struct kvm_vcpu *vcpu;
+ int i;
+
+ spin_lock(&kvm_lock);
+ list_for_each_entry(vm, &vm_list, vm_list)
+ for (i = 0; i < KVM_MAX_VCPUS; ++i) {
+ vcpu = &vm->vcpus[i];
+ /*
+ * If the vcpu is locked, then it is running on some
+ * other cpu and therefore it is not cached on the
+ * cpu in question.
+ *
+ * If it's not locked, check the last cpu it executed
+ * on.
+ */
+ if (mutex_trylock(&vcpu->mutex)) {
+ if (vcpu->cpu == cpu) {
+ kvm_arch_ops->vcpu_decache(vcpu);
+ vcpu->cpu = -1;
+ }
+ mutex_unlock(&vcpu->mutex);
+ }
+ }
+ spin_unlock(&kvm_lock);
+}
+
+static int kvm_cpu_hotplug(struct notifier_block *notifier, unsigned long val,
+ void *v)
+{
+ int cpu = (long)v;
+
+ switch (val) {
+ case CPU_DEAD:
+ case CPU_UP_CANCELED:
+ decache_vcpus_on_cpu(cpu);
+ smp_call_function_single(cpu, kvm_arch_ops->hardware_disable,
+ NULL, 0, 1);
+ break;
+ case CPU_UP_PREPARE:
+ smp_call_function_single(cpu, kvm_arch_ops->hardware_enable,
+ NULL, 0, 1);
+ break;
+ }
+ return NOTIFY_OK;
+}
+
+static struct notifier_block kvm_cpu_notifier = {
+ .notifier_call = kvm_cpu_hotplug,
+ .priority = 20, /* must be > scheduler priority */
+};
+
static __init void kvm_init_debug(void)
{
struct kvm_stats_debugfs_item *p;
@@ -2085,6 +2144,9 @@ int kvm_init_arch(struct kvm_arch_ops *ops, struct module *module)
return r;
on_each_cpu(kvm_arch_ops->hardware_enable, NULL, 0, 1);
+ r = register_cpu_notifier(&kvm_cpu_notifier);
+ if (r)
+ goto out_free_1;
register_reboot_notifier(&kvm_reboot_notifier);
kvm_chardev_ops.owner = module;
@@ -2099,6 +2161,8 @@ int kvm_init_arch(struct kvm_arch_ops *ops, struct module *module)
out_free:
unregister_reboot_notifier(&kvm_reboot_notifier);
+ unregister_cpu_notifier(&kvm_cpu_notifier);
+out_free_1:
on_each_cpu(kvm_arch_ops->hardware_disable, NULL, 0, 1);
kvm_arch_ops->hardware_unsetup();
return r;