On Thu, 2021-11-04 at 08:13 -0700, Dave Hansen wrote: > On 11/4/21 8:04 AM, Jarkko Sakkinen wrote: > > > Do we also need to deal with truncating the PCMD? (For those watching > > > along at home, there are two things SGX swaps to RAM: the actual page > > > data and also some metadata that ensures page integrity and helps > > > prevent things like rolling back to old versions of swapped pages) > > Yes. > > > > This can be achieved by iterating through all of the enclave pages, > > which share the same shmem page for storing their PCMD's, as the one > > being faulted back. If none of those pages is swapped, the PCMD page can > > safely truncated. > > I was thinking we could just read the page. If it's all 0's, truncate it. Hmm... did ELDU zero PCMD as a side-effect? It should be fairly effecient just to check the pages by using encl->page_tree. /Jarkko
