Commit 6d4e4c4f authored by Avi Kivity's avatar Avi Kivity
Browse files

KVM: Disallow fork() and similar games when using a VM



We don't want the meaning of guest userspace changing under our feet.
Signed-off-by: default avatarAvi Kivity <avi@qumranet.com>
parent 76c35c6e
......@@ -305,6 +305,7 @@ struct kvm_vm_stat {
struct kvm {
struct mutex lock; /* protects everything except vcpus */
struct mm_struct *mm; /* userspace tied to this vm */
int naliases;
struct kvm_mem_alias aliases[KVM_ALIAS_SLOTS];
int nmemslots;
......
......@@ -165,6 +165,8 @@ static struct kvm *kvm_create_vm(void)
if (IS_ERR(kvm))
goto out;
kvm->mm = current->mm;
atomic_inc(&kvm->mm->mm_count);
kvm_io_bus_init(&kvm->pio_bus);
mutex_init(&kvm->lock);
kvm_io_bus_init(&kvm->mmio_bus);
......@@ -202,12 +204,15 @@ void kvm_free_physmem(struct kvm *kvm)
static void kvm_destroy_vm(struct kvm *kvm)
{
struct mm_struct *mm = kvm->mm;
spin_lock(&kvm_lock);
list_del(&kvm->vm_list);
spin_unlock(&kvm_lock);
kvm_io_bus_destroy(&kvm->pio_bus);
kvm_io_bus_destroy(&kvm->mmio_bus);
kvm_arch_destroy_vm(kvm);
mmdrop(mm);
}
static int kvm_vm_release(struct inode *inode, struct file *filp)
......@@ -818,6 +823,8 @@ static long kvm_vcpu_ioctl(struct file *filp,
void __user *argp = (void __user *)arg;
int r;
if (vcpu->kvm->mm != current->mm)
return -EIO;
switch (ioctl) {
case KVM_RUN:
r = -EINVAL;
......@@ -976,6 +983,8 @@ static long kvm_vm_ioctl(struct file *filp,
void __user *argp = (void __user *)arg;
int r;
if (kvm->mm != current->mm)
return -EIO;
switch (ioctl) {
case KVM_CREATE_VCPU:
r = kvm_vm_ioctl_create_vcpu(kvm, arg);
......
......@@ -393,6 +393,7 @@ void fastcall __mmdrop(struct mm_struct *mm)
destroy_context(mm);
free_mm(mm);
}
EXPORT_SYMBOL_GPL(__mmdrop);
/*
* Decrement the use count and release all resources for an mm.
......
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