Hi Ard,
Thanks a lot for review!
I see some issues with the v4.9 based backport.
First of all, S/W PAN is enabled on LSK but not on LTS, and the way it interoperates with KPTI is rather intricate. So perhaps it makes sense to only do the backport for LSK directly, rather than backport it to LTS and merge it in.
Well, it's a trick issue of software PAN feature crossing. The backport aim to LTS, so picking up it may isn't a good idea for LTS. And ARM's opinion is also split it out from backport.
Then, there is the handling of to contiguous bit in the page tables. These patches that you backported into the kpti-v4.9-temp branch> arm64: mm: set the contiguous bit for kernel mappings where appropriate arm64: mm: replace 'block_mappings_allowed' with 'page_mappings_only' arm64: mm: BUG on unsupported manipulations of live kernel mappings
(which I wrote myself btw) have been reverted and replaced upstream, and adding those to a stable kernel is likely to cause breakage (i.e, TLB conflict aborts)
Sorry about the the temp branch on lsk, it's a temporary/private branch for middle work tracking during my vacation. The announced and public branch should be on https://git.linaro.org/kernel/speculation-fixes-staging.git/log/?h=v4.9-all-...
And the final/public branch has no above 3 patches.
So first of all, we need to decide on the scope for this backport (LTS or LSK). Also, whether we want Meltdown mitigations (which are essential for Cortex-A75 but only a nice to have for other cores iff KASLR is enabled).
Yes, it need a bit more work to included it into lsk, but that's the requirement I just got.
Thanks ALex
Mark, do you have any insight into what the members are requesting exactly for v4.9?
Thanks, Ard.