KVM: Disable pagefaults during copy_from_user_inatomic()

With CONFIG_PREEMPT=n, this is needed in order to disable the fault-in
code from sleeping.

Signed-off-by: Andrea Arcangeli <andrea@qumranet.com>
Signed-off-by: Avi Kivity <avi@qumranet.com>

1 files changed, 2 insertions, 0 deletions

diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c
index 7972e3aa2cae..cf6df5167af6 100644
--- a/virt/kvm/kvm_main.c
+++ b/virt/kvm/kvm_main.c
@@ -554,7 +554,9 @@ int kvm_read_guest_atomic(struct kvm *kvm, gpa_t gpa, void *data,
         addr = gfn_to_hva(kvm, gfn);
         if (kvm_is_error_hva(addr))
                 return -EFAULT;
+        pagefault_disable();
         r = __copy_from_user_inatomic(data, (void __user *)addr + offset, len);
+        pagefault_enable();
         if (r)
                 return -EFAULT;
         return 0;