On Sun, Jan 7, 2018 at 3:35 PM, Ben Hutchings ben@decadent.org.uk wrote:
I have a backport of KPTI/KAISER to 3.16, based on Hugh Dickins's work for 3.18, some upstream changes between 3.16 and 3.18, and other patches that went into 4.4.75.
I sent this out for review on the stable list after quite minimal testing, but have done more since then. On bare metal (Sandy Bridge, with pcid but not invpcid) it crashes at boot. In fact it reboots without any panic message, suggesting a triple fault, as soon as I apply the patch that turns on CR4.PCIDE, i.e. without KPTI itself.
Using the 'nopcid' kernel parameter gets it to boot but it's somewhat unstable even after that - once I start another kernel build I see programs segfaulting. So I'm guessing I've screwed up some of the TLB stuff.
I'm going to continue investigating this myself before making a release, but would really appreciate any time people can spare to review this patch series.
(I haven't found any such regression in 3.2.98.)
Ben.
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Hi Ben, I'm not on that "stable list", and don't see where it is archived, so this is the first I've heard of your 3.16 port (which does sound from your description like you've approached it in exactly the right way).
Could you please attach a tarfile of git-format-patches since 3.16.52 that we could look through - that will be easier to manage than downloading 40 mails or whatever - thanks.
Hugh