KVM: Add kvm_read_guest_atomic()

[deliverable/linux.git] / virt / kvm / kvm_main.c

diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c
index 678e80561b7487548cb09f1fbab355752bd4fc85..8d0b7c16c2f781b6c3b120115bf1442c16df4d5d 100644 (file)
--- a/virt/kvm/kvm_main.c
+++ b/virt/kvm/kvm_main.c
@@ -541,6 +541,26 @@ int kvm_read_guest(struct kvm *kvm, gpa_t gpa, void *data, unsigned long len)
 }
 EXPORT_SYMBOL_GPL(kvm_read_guest);
 
+int kvm_read_guest_atomic(struct kvm *kvm, gpa_t gpa, void *data,
+                         unsigned long len)
+{
+       int r;
+       unsigned long addr;
+       gfn_t gfn = gpa >> PAGE_SHIFT;
+       int offset = offset_in_page(gpa);
+
+       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;
+}
+EXPORT_SYMBOL(kvm_read_guest_atomic);
+
 int kvm_write_guest_page(struct kvm *kvm, gfn_t gfn, const void *data,
                         int offset, int len)
 {