KVM: Assume that writes smaller than 4 bytes are to non-pagetable pages
This allows us to remove write protection earlier than otherwise. Should
some mad OS choose to use byte writes to update pagetables, it will suffer
a performance hit, but still work correctly.
Signed-off-by: Avi Kivity <avi@qumranet.com>
diff --git a/drivers/kvm/mmu.c b/drivers/kvm/mmu.c
index e8e2281..2277b7c 100644
--- a/drivers/kvm/mmu.c
+++ b/drivers/kvm/mmu.c
@@ -1169,6 +1169,7 @@
continue;
pte_size = page->role.glevels == PT32_ROOT_LEVEL ? 4 : 8;
misaligned = (offset ^ (offset + bytes - 1)) & ~(pte_size - 1);
+ misaligned |= bytes < 4;
if (misaligned || flooded) {
/*
* Misaligned accesses are too much trouble to fix