On 27/11/15 16:22, Han, Huaitong wrote: > On Fri, 2015-11-27 at 12:59 +0000, Andrew Cooper wrote: >> Just for my own understand, do you have a sample use-case for >> protection >> keys? >> >> As everything can WRPKRU, I cant see how it would actually be useful. >> Clearly there is a usecase or you (Intel) wouldn't have gone to the >> effort of putting into silicon. >> >> ~Andrew > I understand PKU is a active memory protection, pkru register is thread > -private, every thread can only change its pkru value, it is a > enhancement of pte write/access, it provides two advantage: > 1.During permission changes, we only need update pkru register instead > of pte, so it can reduce the need to perform TLB shootdowns. > 2.Compared with traditional read and write permissions, it can provide > thread-private permissions.
So it is a feature which allows threads to cooperatively prevent themselves trampling on each other. I can see this being useful for debugging and robustness. ~Andrew _______________________________________________ Xen-devel mailing list Xen-devel@lists.xen.org http://lists.xen.org/xen-devel
