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

Takuya Yoshikawa
2010-04-20T10:57:04Z

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@oss.ntt.co.jp>
Signed-off-by: Fernando Luis Vazquez Cao <fernando@oss.ntt.co.jp>
---
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