KVM: MMU: Don't cache guest access bits in the shadow page table

This was once used to avoid accessing the guest pte when upgrading
the shadow pte from read-only to read-write.  But usually we need
to set the guest pte dirty or accessed bits anyway, so this wasn't
really exploited.

Signed-off-by: Avi Kivity <avi@qumranet.com>

drivers/kvm/paging_tmpl.h

@@ -219,7 +219,6 @@ static void FNAME(set_pte_common)(struct kvm_vcpu *vcpu,
 
 	spte |= PT_PRESENT_MASK | PT_ACCESSED_MASK | PT_DIRTY_MASK;
 	spte |= *gpte & PT64_NX_MASK;
-	spte |= access_bits << PT_SHADOW_BITS_OFFSET;
 	if (!dirty)
 		access_bits &= ~PT_WRITABLE_MASK;