KVM: Avoid checking huge page mappings in get_dirty_log()

Dropped such mappings when we enabled dirty logging and we will never
create new ones until we stop the logging.

For this we introduce a new function which can be used to write protect
a range of PT level pages: although we do not need to care about a range
of pages at this point, the following patch will need this feature to
optimize the write protection of many pages.

Signed-off-by: Takuya Yoshikawa <yoshikawa.takuya@oss.ntt.co.jp>
Signed-off-by: Avi Kivity <avi@redhat.com>

1 files changed, 3 insertions, 5 deletions

diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index 99b738028fc..813ebf1e55a 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -3095,13 +3095,11 @@ static void write_protect_slot(struct kvm *kvm,
 
         /* Not many dirty pages compared to # of shadow pages. */
         if (nr_dirty_pages < kvm->arch.n_used_mmu_pages) {
-                unsigned long gfn_offset;
+                gfn_t offset;
 
-                for_each_set_bit(gfn_offset, dirty_bitmap, memslot->npages) {
-                        unsigned long gfn = memslot->base_gfn + gfn_offset;
+                for_each_set_bit(offset, dirty_bitmap, memslot->npages)
+                        kvm_mmu_write_protect_pt_masked(kvm, memslot, offset, 1);
 
-                        kvm_mmu_rmap_write_protect(kvm, gfn, memslot);
-                }
                 kvm_flush_remote_tlbs(kvm);
         } else
                 kvm_mmu_slot_remove_write_access(kvm, memslot->id);