On 12/21/2015 03:02 PM, Andy Lutomirski wrote: > 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?
Yep, but that's with a concrete benefit in mind. > 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. Yep, agreed. -- 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/
