[PATCH RFC v2 4/6] KVM: change mark_page_dirty() to handle endian issues explicitly

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We are now using generic___set_le_bit() to make dirty bitmaps le.
Though this works well, we have to replace __set_bit() to appropriate
uaccess function to move dirty bitmaps to user space. So this patch
splits generic___set_le_bit() and prepares for that.

Signed-off-by: Takuya Yoshikawa <yoshikawa.takuya@xxxxxxxxxxxxx>
Signed-off-by: Fernando Luis Vazquez Cao <fernando@xxxxxxxxxxxxx>
---
 virt/kvm/kvm_main.c |   16 +++++++++++-----
 1 files changed, 11 insertions(+), 5 deletions(-)

diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c
index 6908304..66c4daf 100644
--- a/virt/kvm/kvm_main.c
+++ b/virt/kvm/kvm_main.c
@@ -1194,6 +1194,15 @@ int kvm_clear_guest(struct kvm *kvm, gpa_t gpa, unsigned long len)
 }
 EXPORT_SYMBOL_GPL(kvm_clear_guest);
 
+static int __mark_page_dirty(unsigned long nr,
+			     unsigned long *dirty_bitmap)
+{
+#ifdef __BIG_ENDIAN
+	nr = nr ^ BITOP_LE_SWIZZLE;
+#endif
+	__set_bit(nr, dirty_bitmap);
+}
+
 void mark_page_dirty(struct kvm *kvm, gfn_t gfn)
 {
 	struct kvm_memory_slot *memslot;
@@ -1203,11 +1212,8 @@ void mark_page_dirty(struct kvm *kvm, gfn_t gfn)
 	if (memslot && memslot->dirty_bitmap) {
 		unsigned long rel_gfn = gfn - memslot->base_gfn;
 
-		/* avoid RMW */
-		if (!generic_test_le_bit(rel_gfn, memslot->dirty_bitmap)) {
-			generic___set_le_bit(rel_gfn, memslot->dirty_bitmap);
-			memslot->is_dirty = true;
-		}
+		__mark_page_dirty(rel_gfn, memslot->dirty_bitmap);
+		memslot->is_dirty = true;
 	}
 }
 
-- 
1.6.3.3

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