On 5 January 2018 at 16:06, Greg Kroah-Hartman <gre...@linuxfoundation.org> wrote: > On Thu, Jan 04, 2018 at 10:23:40AM -0800, Florian Fainelli wrote: >> On 01/03/2018 10:50 PM, Greg Kroah-Hartman wrote: >> > On Wed, Jan 03, 2018 at 09:17:26PM -0800, Florian Fainelli wrote: >> >> On 12/11/2017 09:59 AM, Catalin Marinas wrote: >> >>> On Wed, Dec 06, 2017 at 12:35:19PM +0000, Will Deacon wrote: >> >>>> Patches are also pushed here: >> >>>> >> >>>> git://git.kernel.org/pub/scm/linux/kernel/git/will/linux.git kpti >> >>>> >> >>>> Feedback and testing welcome. At this point, I'd like to start thinking >> >>>> about getting this merged for 4.16. >> >>> >> >>> For the record, the fixed up version was pushed by Will here: >> >>> >> >>> git://git.kernel.org/pub/scm/linux/kernel/git/arm64/linux.git kpti >> >>> >> >>> and I queued it for 4.16 in the arm64 for-next/core branch (same tree as >> >>> above). >> >> >> >> Greg proposed the x86/KPTI patches for the stable-4.9.75 queue, is there >> >> a plan to get the ARM64/KPTI patches backported towards stable trees as >> >> well? >> > >> > Stable tree patches have to get into Linus's tree first before I can do >> > anything :) >> > >> > Anyway, once that happens, yes, there is a plan, but it's a bit >> > "different", and I'll talk about it once these are merged. >> >> Great, thanks! Bonus question, if someone is using any of the affected >> devices in AArch32, should we be expecting to see ARM/Linux changes as >> well, that is, is there a plan to come up with a kpti implementation for >> ARM? > > I have not heard of anyone working on this for any arm32 platforms, > as of this time, sorry. > > Which makes me worry about my android tv, glad I don't connect it to the > network :( >
The only ARM variant that is currently known to be affected by Meltdown/variant 3 (which is what KPTI addresses) is the Cortex-A75, which is a 64-bit core. That still means 32-bit guests running under KVM will be affected, as well as a 32-bit kernel running on the bare metal, but in practice, 32-bit ARM simply doesn't need KPTI. (My KASLR patches for ARM are a bit in limbo atm, but those would benefit from unmapping the kernel while running in userland as well) As for variants 1/2 aka Spectre, I suppose ARM will need to implement the same nospec/retpoline primitives that are being proposed for other arches, but that work is not as fleshed out yet.
