KVM: introduce kvm_read_guest_cached

[linux-3.10.git] / virt / kvm / kvm_main.c

diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c
index 11d2783eb9dfbe887d31f755c884ce00eeb89436..d5ef9ebcaff76153688d5f4df0ed5974503fd989 100644 (file)
--- a/virt/kvm/kvm_main.c
+++ b/virt/kvm/kvm_main.c
@@ -1418,6 +1418,26 @@ int kvm_write_guest_cached(struct kvm *kvm, struct gfn_to_hva_cache *ghc,
 }
 EXPORT_SYMBOL_GPL(kvm_write_guest_cached);
 
+int kvm_read_guest_cached(struct kvm *kvm, struct gfn_to_hva_cache *ghc,
+                          void *data, unsigned long len)
+{
+       struct kvm_memslots *slots = kvm_memslots(kvm);
+       int r;
+
+       if (slots->generation != ghc->generation)
+               kvm_gfn_to_hva_cache_init(kvm, ghc, ghc->gpa);
+
+       if (kvm_is_error_hva(ghc->hva))
+               return -EFAULT;
+
+       r = __copy_from_user(data, (void __user *)ghc->hva, len);
+       if (r)
+               return -EFAULT;
+
+       return 0;
+}
+EXPORT_SYMBOL_GPL(kvm_read_guest_cached);
+
 int kvm_clear_guest_page(struct kvm *kvm, gfn_t gfn, int offset, int len)
 {
        return kvm_write_guest_page(kvm, gfn, (const void *) empty_zero_page,