KVM: introduce gfn_to_hva()

Convert a guest frame number to the corresponding host virtual address.

Signed-off-by: Izik Eidus <izike@qumranet.com>
Signed-off-by: Avi Kivity <avi@qumranet.com>

1 files changed, 17 insertions, 8 deletions

diff --git a/drivers/kvm/kvm_main.c b/drivers/kvm/kvm_main.c
index dfb65e2f87ee..04544aecf22f 100644
--- a/drivers/kvm/kvm_main.c
+++ b/drivers/kvm/kvm_main.c
@@ -559,28 +559,37 @@ int kvm_is_visible_gfn(struct kvm *kvm, gfn_t gfn)
 }
 EXPORT_SYMBOL_GPL(kvm_is_visible_gfn);
 
+static unsigned long gfn_to_hva(struct kvm *kvm, gfn_t gfn)
+{
+        struct kvm_memory_slot *slot;
+
+        gfn = unalias_gfn(kvm, gfn);
+        slot = __gfn_to_memslot(kvm, gfn);
+        if (!slot)
+                return bad_hva();
+        return (slot->userspace_addr + (gfn - slot->base_gfn) * PAGE_SIZE);
+}
+
 /*
  * Requires current->mm->mmap_sem to be held
  */
 static struct page *__gfn_to_page(struct kvm *kvm, gfn_t gfn)
 {
-        struct kvm_memory_slot *slot;
         struct page *page[1];
+        unsigned long addr;
         int npages;
 
         might_sleep();
 
-        gfn = unalias_gfn(kvm, gfn);
-        slot = __gfn_to_memslot(kvm, gfn);
-        if (!slot) {
+        addr = gfn_to_hva(kvm, gfn);
+        if (kvm_is_error_hva(addr)) {
                 get_page(bad_page);
                 return bad_page;
         }
 
-        npages = get_user_pages(current, current->mm,
-                                slot->userspace_addr
-                                + (gfn - slot->base_gfn) * PAGE_SIZE, 1,
-                                1, 1, page, NULL);
+        npages = get_user_pages(current, current->mm, addr, 1, 1, 1, page,
+                                NULL);
+
         if (npages != 1) {
                 get_page(bad_page);
                 return bad_page;