KVM: reuse memslot in kvm_write_guest_page

Caching memslot value and using mark_page_dirty_in_slot() avoids another
O(log N) search when dirtying the page.

Signed-off-by: Radim Krčmář <rkrcmar@redhat.com>
Message-Id: <1428695247-27603-1-git-send-email-rkrcmar@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

1 files changed, 4 insertions, 2 deletions

diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c
index 90977418aeb6..b6d415156283 100644
--- a/virt/kvm/kvm_main.c
+++ b/virt/kvm/kvm_main.c
@@ -1590,15 +1590,17 @@ int kvm_write_guest_page(struct kvm *kvm, gfn_t gfn, const void *data,
                          int offset, int len)
 {
         int r;
+        struct kvm_memory_slot *memslot;
         unsigned long addr;
 
-        addr = gfn_to_hva(kvm, gfn);
+        memslot = gfn_to_memslot(kvm, gfn);
+        addr = gfn_to_hva_memslot(memslot, gfn);
         if (kvm_is_error_hva(addr))
                 return -EFAULT;
         r = __copy_to_user((void __user *)addr + offset, data, len);
         if (r)
                 return -EFAULT;
-        mark_page_dirty(kvm, gfn);
+        mark_page_dirty_in_slot(kvm, memslot, gfn);
         return 0;
 }
 EXPORT_SYMBOL_GPL(kvm_write_guest_page);