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authorAlexander Graf <agraf@suse.de>2009-09-15 11:37:46 +0200
committerAvi Kivity <avi@redhat.com>2009-12-03 09:32:10 +0200
commit10474ae8945ce08622fd1f3464e55bd817bf2376 (patch)
treed390843b5107e600fbbf745eb24d85d745fe449f
parente8b3433a5c062e94e34cadb6144c10689a497bc3 (diff)
KVM: Activate Virtualization On Demand
X86 CPUs need to have some magic happening to enable the virtualization extensions on them. This magic can result in unpleasant results for users, like blocking other VMMs from working (vmx) or using invalid TLB entries (svm). Currently KVM activates virtualization when the respective kernel module is loaded. This blocks us from autoloading KVM modules without breaking other VMMs. To circumvent this problem at least a bit, this patch introduces on demand activation of virtualization. This means, that instead virtualization is enabled on creation of the first virtual machine and disabled on destruction of the last one. So using this, KVM can be easily autoloaded, while keeping other hypervisors usable. Signed-off-by: Alexander Graf <agraf@suse.de> Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com> Signed-off-by: Avi Kivity <avi@redhat.com>
-rw-r--r--arch/ia64/kvm/kvm-ia64.c8
-rw-r--r--arch/powerpc/kvm/powerpc.c3
-rw-r--r--arch/s390/kvm/kvm-s390.c3
-rw-r--r--arch/x86/include/asm/kvm_host.h2
-rw-r--r--arch/x86/kvm/svm.c13
-rw-r--r--arch/x86/kvm/vmx.c11
-rw-r--r--arch/x86/kvm/x86.c4
-rw-r--r--include/linux/kvm_host.h2
-rw-r--r--virt/kvm/kvm_main.c90
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: