9 files changed, 108 insertions, 28 deletions

diff --git a/arch/ia64/kvm/kvm-ia64.c b/arch/ia64/kvm/kvm-ia64.c
index f6471c882667..5fdeec5fddcf 100644
--- a/arch/ia64/kvm/kvm-ia64.c
+++ b/arch/ia64/kvm/kvm-ia64.c
@@ -124,7 +124,7 @@ long ia64_pal_vp_create(u64 *vpd, u64 *host_iva, u64 *opt_handler)
 
 static  DEFINE_SPINLOCK(vp_lock);
 
-void kvm_arch_hardware_enable(void *garbage)
+int kvm_arch_hardware_enable(void *garbage)
 {
         long  status;
         long  tmp_base;
@@ -137,7 +137,7 @@ void kvm_arch_hardware_enable(void *garbage)
         slot = ia64_itr_entry(0x3, KVM_VMM_BASE, pte, KVM_VMM_SHIFT);
         local_irq_restore(saved_psr);
         if (slot < 0)
-                return;
+                return -EINVAL;
 
         spin_lock(&vp_lock);
         status = ia64_pal_vp_init_env(kvm_vsa_base ?
@@ -145,7 +145,7 @@ void kvm_arch_hardware_enable(void *garbage)
                         __pa(kvm_vm_buffer), KVM_VM_BUFFER_BASE, &tmp_base);
         if (status != 0) {
                 printk(KERN_WARNING"kvm: Failed to Enable VT Support!!!!\n");
-                return ;
+                return -EINVAL;
         }
 
         if (!kvm_vsa_base) {
@@ -154,6 +154,8 @@ void kvm_arch_hardware_enable(void *garbage)
         }
         spin_unlock(&vp_lock);
         ia64_ptr_entry(0x3, slot);
+
+        return 0;
 }
 
 void kvm_arch_hardware_disable(void *garbage)
diff --git a/arch/powerpc/kvm/powerpc.c b/arch/powerpc/kvm/powerpc.c
index 95af62217b6b..5902bbc2411e 100644
--- a/arch/powerpc/kvm/powerpc.c
+++ b/arch/powerpc/kvm/powerpc.c
@@ -78,8 +78,9 @@ int kvmppc_emulate_mmio(struct kvm_run *run, struct kvm_vcpu *vcpu)
         return r;
 }
 
-void kvm_arch_hardware_enable(void *garbage)
+int kvm_arch_hardware_enable(void *garbage)
 {
+        return 0;
 }
 
 void kvm_arch_hardware_disable(void *garbage)
diff --git a/arch/s390/kvm/kvm-s390.c b/arch/s390/kvm/kvm-s390.c
index 00e2ce8e91f5..544505893c9f 100644
--- a/arch/s390/kvm/kvm-s390.c
+++ b/arch/s390/kvm/kvm-s390.c
@@ -74,9 +74,10 @@ struct kvm_stats_debugfs_item debugfs_entries[] = {
 static unsigned long long *facilities;
 
 /* Section: not file related */
-void kvm_arch_hardware_enable(void *garbage)
+int kvm_arch_hardware_enable(void *garbage)
 {
         /* every s390 is virtualization enabled ;-) */
+        return 0;
 }
 
 void kvm_arch_hardware_disable(void *garbage)
diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h
index a46e2dd9aca8..295c7c4d9c90 100644
--- a/arch/x86/include/asm/kvm_host.h
+++ b/arch/x86/include/asm/kvm_host.h
@@ -459,7 +459,7 @@ struct descriptor_table {
 struct kvm_x86_ops {
         int (*cpu_has_kvm_support)(void);          /* __init */
         int (*disabled_by_bios)(void);             /* __init */
-        void (*hardware_enable)(void *dummy);      /* __init */
+        int (*hardware_enable)(void *dummy);
         void (*hardware_disable)(void *dummy);
         void (*check_processor_compatibility)(void *rtn);
         int (*hardware_setup)(void);               /* __init */
diff --git a/arch/x86/kvm/svm.c b/arch/x86/kvm/svm.c
index f54c4f9d2865..59fe4d54da11 100644
--- a/arch/x86/kvm/svm.c
+++ b/arch/x86/kvm/svm.c
@@ -316,7 +316,7 @@ static void svm_hardware_disable(void *garbage)
         cpu_svm_disable();
 }
 
-static void svm_hardware_enable(void *garbage)
+static int svm_hardware_enable(void *garbage)
 {
 
         struct svm_cpu_data *svm_data;
@@ -325,16 +325,20 @@ static void svm_hardware_enable(void *garbage)
         struct desc_struct *gdt;
         int me = raw_smp_processor_id();
 
+        rdmsrl(MSR_EFER, efer);
+        if (efer & EFER_SVME)
+                return -EBUSY;
+
         if (!has_svm()) {
                 printk(KERN_ERR "svm_cpu_init: err EOPNOTSUPP on %d\n", me);
-                return;
+                return -EINVAL;
         }
         svm_data = per_cpu(svm_data, me);
 
         if (!svm_data) {
                 printk(KERN_ERR "svm_cpu_init: svm_data is NULL on %d\n",
                        me);
-                return;
+                return -EINVAL;
         }
 
         svm_data->asid_generation = 1;
@@ -345,11 +349,12 @@ static void svm_hardware_enable(void *garbage)
         gdt = (struct desc_struct *)gdt_descr.base;
         svm_data->tss_desc = (struct kvm_ldttss_desc *)(gdt + GDT_ENTRY_TSS);
 
-        rdmsrl(MSR_EFER, efer);
         wrmsrl(MSR_EFER, efer | EFER_SVME);
 
         wrmsrl(MSR_VM_HSAVE_PA,
                page_to_pfn(svm_data->save_area) << PAGE_SHIFT);
+
+        return 0;
 }
 
 static void svm_cpu_uninit(int cpu)
diff --git a/arch/x86/kvm/vmx.c b/arch/x86/kvm/vmx.c
index 73cb5dd960cf..a187570e4837 100644
--- a/arch/x86/kvm/vmx.c
+++ b/arch/x86/kvm/vmx.c
@@ -1138,12 +1138,15 @@ static __init int vmx_disabled_by_bios(void)
         /* locked but not enabled */
 }
 
-static void hardware_enable(void *garbage)
+static int hardware_enable(void *garbage)
 {
         int cpu = raw_smp_processor_id();
         u64 phys_addr = __pa(per_cpu(vmxarea, cpu));
         u64 old;
 
+        if (read_cr4() & X86_CR4_VMXE)
+                return -EBUSY;
+
         INIT_LIST_HEAD(&per_cpu(vcpus_on_cpu, cpu));
         rdmsrl(MSR_IA32_FEATURE_CONTROL, old);
         if ((old & (FEATURE_CONTROL_LOCKED |
@@ -1158,6 +1161,10 @@ static void hardware_enable(void *garbage)
         asm volatile (ASM_VMX_VMXON_RAX
                       : : "a"(&phys_addr), "m"(phys_addr)
                       : "memory", "cc");
+
+        ept_sync_global();
+
+        return 0;
 }
 
 static void vmclear_local_vcpus(void)
@@ -4040,8 +4047,6 @@ static int __init vmx_init(void)
         if (bypass_guest_pf)
                 kvm_mmu_set_nonpresent_ptes(~0xffeull, 0ull);
 
-        ept_sync_global();
-
         return 0;
 
 out3:
diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index 829e3063e2ab..3d83de8bcbf4 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -4691,9 +4691,9 @@ int kvm_arch_vcpu_reset(struct kvm_vcpu *vcpu)
         return kvm_x86_ops->vcpu_reset(vcpu);
 }
 
-void kvm_arch_hardware_enable(void *garbage)
+int kvm_arch_hardware_enable(void *garbage)
 {
-        kvm_x86_ops->hardware_enable(garbage);
+        return kvm_x86_ops->hardware_enable(garbage);
 }
 
 void kvm_arch_hardware_disable(void *garbage)
diff --git a/include/linux/kvm_host.h b/include/linux/kvm_host.h
index c0a1cc35f080..b985a29d8175 100644
--- a/include/linux/kvm_host.h
+++ b/include/linux/kvm_host.h
@@ -345,7 +345,7 @@ int kvm_arch_vcpu_setup(struct kvm_vcpu *vcpu);
 void kvm_arch_vcpu_destroy(struct kvm_vcpu *vcpu);
 
 int kvm_arch_vcpu_reset(struct kvm_vcpu *vcpu);
-void kvm_arch_hardware_enable(void *garbage);
+int kvm_arch_hardware_enable(void *garbage);
 void kvm_arch_hardware_disable(void *garbage);
 int kvm_arch_hardware_setup(void);
 void kvm_arch_hardware_unsetup(void);
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: