On Thu, May 05, 2022 at 11:03:18AM +0000, Tian, Kevin wrote: > iiuc the purpose of 'write-protection' here is to capture in-fly dirty pages > in the said race window until unmap and iotlb is invalidated is completed. No, the purpose is to perform "unmap" without destroying the dirty bit in the process. If an IOMMU architecture has a way to render the page unmaped and flush back the dirty bit/not destroy then it doesn't require a write protect pass. Jason
