On Fri, 2021-09-17 at 14:38 -0700, Tony Luck wrote: > SGX EPC pages go through the following life cycle: > > DIRTY ---> FREE ---> IN-USE --\ > ^ | > \-----------------/ > > Recovery action for poison for a DIRTY or FREE page is simple. Just > make sure never to allocate the page. IN-USE pages need some extra > handling. > > It would be good to use the sgx_epc_page->owner field as an indicator > of where an EPC page is currently in that cycle (owner != NULL means > the EPC page is IN-USE). But there is one caller, sgx_alloc_va_page(), > that calls with NULL. > > Since there are multiple uses of the "owner" field with different types > change the sgx_epc_page structure to define an anonymous union with > each of the uses explicitly called out. But it's still always a pointer. And not only that, but two alternative fields in that union have *exactly* the same type, so it's kind of artifically representing the problem more complex than it really is. I'm not just getting, why all this complexity, and not a few casts instead? I neither get the rename of "owner" to "private". It serves very little value. I'm not saying that "owner" is best name ever but it's not *that* confusing either. That I'm sure that it is definitely not very productive to rename it. Also there was still this "dirty". We could use ((void *)-1), which was also suggested for earlier revisions. /Jarkko
