Hi,
On Thu, Dec 19, 2024 at 9:51 AM Will Deacon will@kernel.org wrote:
As of right now, the only CPU IDs added to the "unaffected" list are ARM Cortex A35, A53, and A55. This list was created by looking at older cores listed in cputype.h that weren't listed in the "affected" list previously.
There's a list of affected CPUs from Arm here:
https://developer.arm.com/Arm%20Security%20Center/Spectre-BHB
(obviously only covers their own designs).
So it looks like A510 and A520 should be unaffected too, although I didn't check exhaustively.
I was hoping that newer cores would hit the supports_csv2p3() check and be considered safe, but I guess the white paper explicitly says that A510 doesn't implement it and is still considered safe. I looked up the TRM of A520 and it looks like it also doesn't set CSV2P3, so I guess I'll add that one too.
It also looks like A715 is affected but the whitepaper doesn't tell you what version of 'k' to use...
It doesn't? I see a "k" of 38 there. Wow, and Neoverse N2 needs 132!!!
...though I guess on newer steppings of those chips they'll just use "clear BHB", which seems available and is the preferred mitigation?