From: Isaku Yamahata <isaku.yamahata@xxxxxxxxx>
hardware_enable/disable_nolock() check if the hardware is already
enabled/disabled and work as nop when they are called multiple times. Also
kvm_usage_count tracks the number of the existing VMs.
When VM is created/destroyed by kvm_create/destroy_vm(),
hardware_enable/disable_all() and module_get/put() are called. It means
when kvm module is removed, it's guaranteed that there is no vm
(kvm_usage_count = 0) and that hardware_disable_nolock() was called on each
cpus.
Although the module exit function, kvm_exit(), calls
on_each_cpu(hardware_disable_nolock), it's essentially nop. Eliminate nop
call in kvm_exit() and add WARN_ON(kvm_usage_count) to prove that there is
no remaining VMs.
Signed-off-by: Isaku Yamahata <isaku.yamahata@xxxxxxxxx>
---
virt/kvm/kvm_main.c | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)
diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c
index 1376a47fedee..a8c4e62b29ca 100644
--- a/virt/kvm/kvm_main.c
+++ b/virt/kvm/kvm_main.c
@@ -5945,6 +5945,8 @@ void kvm_exit(void)
{
int cpu;
+ WARN_ON(kvm_usage_count);
+
debugfs_remove_recursive(kvm_debugfs_dir);
misc_deregister(&kvm_dev);
for_each_possible_cpu(cpu)
@@ -5954,7 +5956,6 @@ void kvm_exit(void)
unregister_syscore_ops(&kvm_syscore_ops);
unregister_reboot_notifier(&kvm_reboot_notifier);
cpuhp_remove_state_nocalls(CPUHP_AP_KVM_STARTING);
- on_each_cpu(hardware_disable_nolock, NULL, 1);
kvm_arch_hardware_unsetup();
kvm_arch_exit();
kvm_irqfd_exit();
--
2.25.1
