1 files changed, 78 insertions, 12 deletions

diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c
index 38e4d2c34ac1..70c8cbea0a99 100644
--- a/virt/kvm/kvm_main.c
+++ b/virt/kvm/kvm_main.c
@@ -69,6 +69,8 @@ DEFINE_SPINLOCK(kvm_lock);
 LIST_HEAD(vm_list);
 
 static cpumask_var_t cpus_hardware_enabled;
+static int kvm_usage_count = 0;
+static atomic_t hardware_enable_failed;
 
 struct kmem_cache *kvm_vcpu_cache;
 EXPORT_SYMBOL_GPL(kvm_vcpu_cache);
@@ -79,6 +81,8 @@ struct dentry *kvm_debugfs_dir;
 
 static long kvm_vcpu_ioctl(struct file *file, unsigned int ioctl,
                            unsigned long arg);
+static int hardware_enable_all(void);
+static void hardware_disable_all(void);
 
 static bool kvm_rebooting;
 
@@ -339,6 +343,7 @@ static const struct mmu_notifier_ops kvm_mmu_notifier_ops = {
 
 static struct kvm *kvm_create_vm(void)
 {
+        int r = 0;
         struct kvm *kvm = kvm_arch_create_vm();
 #ifdef KVM_COALESCED_MMIO_PAGE_OFFSET
         struct page *page;
@@ -346,6 +351,11 @@ static struct kvm *kvm_create_vm(void)
 
         if (IS_ERR(kvm))
                 goto out;
+
+        r = hardware_enable_all();
+        if (r)
+                goto out_err_nodisable;
+
 #ifdef CONFIG_HAVE_KVM_IRQCHIP
         INIT_HLIST_HEAD(&kvm->mask_notifier_list);
         INIT_HLIST_HEAD(&kvm->irq_ack_notifier_list);
@@ -354,8 +364,8 @@ static struct kvm *kvm_create_vm(void)
 #ifdef KVM_COALESCED_MMIO_PAGE_OFFSET
         page = alloc_page(GFP_KERNEL | __GFP_ZERO);
         if (!page) {
-                kfree(kvm);
-                return ERR_PTR(-ENOMEM);
+                r = -ENOMEM;
+                goto out_err;
         }
         kvm->coalesced_mmio_ring =
                         (struct kvm_coalesced_mmio_ring *)page_address(page);
@@ -363,15 +373,13 @@ static struct kvm *kvm_create_vm(void)
 
 #if defined(CONFIG_MMU_NOTIFIER) && defined(KVM_ARCH_WANT_MMU_NOTIFIER)
         {
-                int err;
                 kvm->mmu_notifier.ops = &kvm_mmu_notifier_ops;
-                err = mmu_notifier_register(&kvm->mmu_notifier, current->mm);
-                if (err) {
+                r = mmu_notifier_register(&kvm->mmu_notifier, current->mm);
+                if (r) {
 #ifdef KVM_COALESCED_MMIO_PAGE_OFFSET
                         put_page(page);
 #endif
-                        kfree(kvm);
-                        return ERR_PTR(err);
+                        goto out_err;
                 }
         }
 #endif
@@ -395,6 +403,12 @@ static struct kvm *kvm_create_vm(void)
 #endif
 out:
         return kvm;
+
+out_err:
+        hardware_disable_all();
+out_err_nodisable:
+        kfree(kvm);
+        return ERR_PTR(r);
 }
 
 /*
@@ -453,6 +467,7 @@ static void kvm_destroy_vm(struct kvm *kvm)
         kvm_arch_flush_shadow(kvm);
 #endif
         kvm_arch_destroy_vm(kvm);
+        hardware_disable_all();
         mmdrop(mm);
 }
 
@@ -1644,11 +1659,21 @@ static struct miscdevice kvm_dev = {
 static void hardware_enable(void *junk)
 {
         int cpu = raw_smp_processor_id();
+        int r;
 
         if (cpumask_test_cpu(cpu, cpus_hardware_enabled))
                 return;
+
         cpumask_set_cpu(cpu, cpus_hardware_enabled);
-        kvm_arch_hardware_enable(NULL);
+
+        r = kvm_arch_hardware_enable(NULL);
+
+        if (r) {
+                cpumask_clear_cpu(cpu, cpus_hardware_enabled);
+                atomic_inc(&hardware_enable_failed);
+                printk(KERN_INFO "kvm: enabling virtualization on "
+                                 "CPU%d failed\n", cpu);
+        }
 }
 
 static void hardware_disable(void *junk)
@@ -1661,11 +1686,52 @@ static void hardware_disable(void *junk)
         kvm_arch_hardware_disable(NULL);
 }
 
+static void hardware_disable_all_nolock(void)
+{
+        BUG_ON(!kvm_usage_count);
+
+        kvm_usage_count--;
+        if (!kvm_usage_count)
+                on_each_cpu(hardware_disable, NULL, 1);
+}
+
+static void hardware_disable_all(void)
+{
+        spin_lock(&kvm_lock);
+        hardware_disable_all_nolock();
+        spin_unlock(&kvm_lock);
+}
+
+static int hardware_enable_all(void)
+{
+        int r = 0;
+
+        spin_lock(&kvm_lock);
+
+        kvm_usage_count++;
+        if (kvm_usage_count == 1) {
+                atomic_set(&hardware_enable_failed, 0);
+                on_each_cpu(hardware_enable, NULL, 1);
+
+                if (atomic_read(&hardware_enable_failed)) {
+                        hardware_disable_all_nolock();
+                        r = -EBUSY;
+                }
+        }
+
+        spin_unlock(&kvm_lock);
+
+        return r;
+}
+
 static int kvm_cpu_hotplug(struct notifier_block *notifier, unsigned long val,
                            void *v)
 {
         int cpu = (long)v;
 
+        if (!kvm_usage_count)
+                return NOTIFY_OK;
+
         val &= ~CPU_TASKS_FROZEN;
         switch (val) {
         case CPU_DYING:
@@ -1868,13 +1934,15 @@ static void kvm_exit_debug(void)
 
 static int kvm_suspend(struct sys_device *dev, pm_message_t state)
 {
-        hardware_disable(NULL);
+        if (kvm_usage_count)
+                hardware_disable(NULL);
         return 0;
 }
 
 static int kvm_resume(struct sys_device *dev)
 {
-        hardware_enable(NULL);
+        if (kvm_usage_count)
+                hardware_enable(NULL);
         return 0;
 }
 
@@ -1949,7 +2017,6 @@ int kvm_init(void *opaque, unsigned int vcpu_size,
                         goto out_free_1;
         }
 
-        on_each_cpu(hardware_enable, NULL, 1);
         r = register_cpu_notifier(&kvm_cpu_notifier);
         if (r)
                 goto out_free_2;
@@ -1999,7 +2066,6 @@ out_free_3:
         unregister_reboot_notifier(&kvm_reboot_notifier);
         unregister_cpu_notifier(&kvm_cpu_notifier);
 out_free_2:
-        on_each_cpu(hardware_disable, NULL, 1);
 out_free_1:
         kvm_arch_hardware_unsetup();
 out_free_0a: