virtualization to be enabled when KVM is initialized.
Cc: Chao Gao <chao.gao@xxxxxxxxx>
Signed-off-by: Sean Christopherson <seanjc@xxxxxxxxxx>
---
virt/kvm/kvm_main.c | 174 ++++++++++++++++----------------------------
1 file changed, 61 insertions(+), 113 deletions(-)
diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c
index d9b0579d3eea..f6b114f42433 100644
--- a/virt/kvm/kvm_main.c
+++ b/virt/kvm/kvm_main.c
@@ -5502,7 +5502,7 @@ static DEFINE_PER_CPU(bool, hardware_enabled);
static DEFINE_MUTEX(kvm_usage_lock);
static int kvm_usage_count;
-static int __hardware_enable_nolock(void)
+static int hardware_enable_nolock(void)
{
if (__this_cpu_read(hardware_enabled))
return 0;
@@ -5517,34 +5517,18 @@ static int __hardware_enable_nolock(void)
return 0;
}
-static void hardware_enable_nolock(void *failed)
-{
- if (__hardware_enable_nolock())
- atomic_inc(failed);
-}
-
static int kvm_online_cpu(unsigned int cpu)
{
- int ret = 0;
-
/*
* Abort the CPU online process if hardware virtualization cannot
* be enabled. Otherwise running VMs would encounter unrecoverable
* errors when scheduled to this CPU.
*/
- mutex_lock(&kvm_usage_lock);
- if (kvm_usage_count)
- ret = __hardware_enable_nolock();
- mutex_unlock(&kvm_usage_lock);
- return ret;
+ return hardware_enable_nolock();
}
static void hardware_disable_nolock(void *junk)
{
- /*
- * Note, hardware_disable_all_nolock() tells all online CPUs to disable
- * hardware, not just CPUs that successfully enabled hardware!
- */
if (!__this_cpu_read(hardware_enabled))
return;
@@ -5555,78 +5539,10 @@ static void hardware_disable_nolock(void *junk)
static int kvm_offline_cpu(unsigned int cpu)
{
- mutex_lock(&kvm_usage_lock);
- if (kvm_usage_count)
- hardware_disable_nolock(NULL);
- mutex_unlock(&kvm_usage_lock);
+ hardware_disable_nolock(NULL);
return 0;
}
-static void hardware_disable_all_nolock(void)
-{
- BUG_ON(!kvm_usage_count);
-
- kvm_usage_count--;
- if (!kvm_usage_count)
- on_each_cpu(hardware_disable_nolock, NULL, 1);
-}
-
-static void hardware_disable_all(void)
-{
- cpus_read_lock();
- mutex_lock(&kvm_usage_lock);
- hardware_disable_all_nolock();
- mutex_unlock(&kvm_usage_lock);
- cpus_read_unlock();
-}
-
-static int hardware_enable_all(void)
-{
- atomic_t failed = ATOMIC_INIT(0);
- int r;
-
- /*
- * Do not enable hardware virtualization if the system is going down.
- * If userspace initiated a forced reboot, e.g. reboot -f, then it's
- * possible for an in-flight KVM_CREATE_VM to trigger hardware enabling
- * after kvm_reboot() is called. Note, this relies on system_state
- * being set _before_ kvm_reboot(), which is why KVM uses a syscore ops
- * hook instead of registering a dedicated reboot notifier (the latter
- * runs before system_state is updated).
- */
- if (system_state == SYSTEM_HALT || system_state == SYSTEM_POWER_OFF ||
- system_state == SYSTEM_RESTART)
- return -EBUSY;
-
- /*
- * When onlining a CPU, cpu_online_mask is set before kvm_online_cpu()
- * is called, and so on_each_cpu() between them includes the CPU that
- * is being onlined. As a result, hardware_enable_nolock() may get
- * invoked before kvm_online_cpu(), which also enables hardware if the
- * usage count is non-zero. Disable CPU hotplug to avoid attempting to
- * enable hardware multiple times.
- */
- cpus_read_lock();
- mutex_lock(&kvm_usage_lock);
-
- r = 0;
-
- kvm_usage_count++;
- if (kvm_usage_count == 1) {
- on_each_cpu(hardware_enable_nolock, &failed, 1);
-
- if (atomic_read(&failed)) {
- hardware_disable_all_nolock();
- r = -EBUSY;
- }
- }
-
- mutex_unlock(&kvm_usage_lock);
- cpus_read_unlock();
-
- return r;
-}
-
static void kvm_shutdown(void)
{
/*
@@ -5658,8 +5574,7 @@ static int kvm_suspend(void)
lockdep_assert_not_held(&kvm_usage_lock);
lockdep_assert_irqs_disabled();
- if (kvm_usage_count)
- hardware_disable_nolock(NULL);
+ hardware_disable_nolock(NULL);
return 0;
}
@@ -5668,8 +5583,7 @@ static void kvm_resume(void)
lockdep_assert_not_held(&kvm_usage_lock);
lockdep_assert_irqs_disabled();
- if (kvm_usage_count)
- WARN_ON_ONCE(__hardware_enable_nolock());
+ WARN_ON_ONCE(hardware_enable_nolock());
}
static struct syscore_ops kvm_syscore_ops = {
@@ -5677,6 +5591,60 @@ static struct syscore_ops kvm_syscore_ops = {
.resume = kvm_resume,
.shutdown = kvm_shutdown,
};
+
+static int hardware_enable_all(void)
+{
+ int r;
+
+ guard(mutex)(&kvm_usage_lock);
+
+ if (kvm_usage_count++)
+ return 0;
+
+ r = cpuhp_setup_state(CPUHP_AP_KVM_ONLINE, "kvm/cpu:online",
+ kvm_online_cpu, kvm_offline_cpu);
+ if (r)
+ goto err_cpuhp;
+
+ register_syscore_ops(&kvm_syscore_ops);
+
+ /*
+ * Undo virtualization enabling and bail if the system is going down.
+ * If userspace initiated a forced reboot, e.g. reboot -f, then it's
+ * possible for an in-flight operation to enable virtualization after
+ * syscore_shutdown() is called, i.e. without kvm_shutdown() being
+ * invoked. Note, this relies on system_state being set _before_
+ * kvm_shutdown(), e.g. to ensure either kvm_shutdown() is invoked
+ * or this CPU observes the impending shutdown. Which is why KVM uses
+ * a syscore ops hook instead of registering a dedicated reboot
+ * notifier (the latter runs before system_state is updated).
+ */
+ if (system_state == SYSTEM_HALT || system_state == SYSTEM_POWER_OFF ||
+ system_state == SYSTEM_RESTART) {
+ r = -EBUSY;
+ goto err_rebooting;
+ }
+
+ return 0;
+
+err_rebooting:
+ unregister_syscore_ops(&kvm_syscore_ops);
+ cpuhp_remove_state(CPUHP_AP_KVM_ONLINE);
+err_cpuhp:
+ --kvm_usage_count;
+ return r;
+}
+
+static void hardware_disable_all(void)
+{
+ guard(mutex)(&kvm_usage_lock);
+
+ if (--kvm_usage_count)
+ return;
+
+ unregister_syscore_ops(&kvm_syscore_ops);
+ cpuhp_remove_state(CPUHP_AP_KVM_ONLINE);
+}
#else /* CONFIG_KVM_GENERIC_HARDWARE_ENABLING */
static int hardware_enable_all(void)
{
@@ -6382,15 +6350,6 @@ int kvm_init(unsigned vcpu_size, unsigned vcpu_align, struct module *module)
int r;
int cpu;
-#ifdef CONFIG_KVM_GENERIC_HARDWARE_ENABLING
- r = cpuhp_setup_state_nocalls(CPUHP_AP_KVM_ONLINE, "kvm/cpu:online",
- kvm_online_cpu, kvm_offline_cpu);
- if (r)
- return r;
-
- register_syscore_ops(&kvm_syscore_ops);
-#endif
-
/* A kmem cache lets us meet the alignment requirements of fx_save. */
if (!vcpu_align)
vcpu_align = __alignof__(struct kvm_vcpu);
@@ -6401,10 +6360,8 @@ int kvm_init(unsigned vcpu_size, unsigned vcpu_align, struct module *module)
offsetofend(struct kvm_vcpu, stats_id)
- offsetof(struct kvm_vcpu, arch),
NULL);
- if (!kvm_vcpu_cache) {
- r = -ENOMEM;
- goto err_vcpu_cache;
- }
+ if (!kvm_vcpu_cache)
+ return -ENOMEM;
for_each_possible_cpu(cpu) {
if (!alloc_cpumask_var_node(&per_cpu(cpu_kick_mask, cpu),
@@ -6461,11 +6418,6 @@ int kvm_init(unsigned vcpu_size, unsigned vcpu_align, struct module *module)
for_each_possible_cpu(cpu)
free_cpumask_var(per_cpu(cpu_kick_mask, cpu));
kmem_cache_destroy(kvm_vcpu_cache);
-err_vcpu_cache:
-#ifdef CONFIG_KVM_GENERIC_HARDWARE_ENABLING
- unregister_syscore_ops(&kvm_syscore_ops);
- cpuhp_remove_state_nocalls(CPUHP_AP_KVM_ONLINE);
-#endif
return r;
}
EXPORT_SYMBOL_GPL(kvm_init);
@@ -6487,10 +6439,6 @@ void kvm_exit(void)
kmem_cache_destroy(kvm_vcpu_cache);
kvm_vfio_ops_exit();
kvm_async_pf_deinit();
-#ifdef CONFIG_KVM_GENERIC_HARDWARE_ENABLING
- unregister_syscore_ops(&kvm_syscore_ops);
- cpuhp_remove_state_nocalls(CPUHP_AP_KVM_ONLINE);
-#endif
kvm_irqfd_exit();
}
EXPORT_SYMBOL_GPL(kvm_exit);