On Mon, Dec 21, 2015 at 3:00 PM, Dave Hansen <dave.han...@linux.intel.com> wrote: > On 12/21/2015 02:52 PM, Andy Lutomirski wrote: >> Perhaps this is silly, but what if the default were changed to deny >> reads and writes for unallocated keys? Is there a use case that >> breaks? > > It's probably a reasonable debugging feature. > > But, anything that takes an XSAVE feature out of its "init state" has > the potential to do a bit of harm because it increases the potential > size of writes during XSAVE. XSAVEOPT will _help_ here, but we probably > don't want to go out of our way to take things out of the init state > when we're unsure of the benefits.
Aren't you already doing that with your magic execute-only thing? Also, if we ever do the deferred-xstate-restore thing that Rik was playing with awhile back, then we'll want to switch to using rdpkru and wrpkru in-kernel directly, and we'll explicitly mask PKRU out of the XRSTOR and XSAVEOPT state, and this particular issue will become irrelevant. --Andy -- Andy Lutomirski AMA Capital Management, LLC -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
