On 25/03/2025 09:36, Mikołaj Lenczewski wrote:
The Break-Before-Make cpu feature supports multiple levels (levels 0-2), and this commit adds a dedicated BBML2 cpufeature to test against support for, as well as a kernel commandline parameter to optionally disable BBML2 altogether. This is a system feature as we might have a big.LITTLE architecture where some cores support BBML2 and some don't, but we want all cores to be available and BBM to default to level 0 (as opposed to having cores without BBML2 not coming online). To support BBML2 in as wide a range of contexts as we can, we want not only the architectural guarantees that BBML2 makes, but additionally want BBML2 to not create TLB conflict aborts. Not causing aborts avoids us having to prove that no recursive faults can be induced in any path that uses BBML2, allowing its use for arbitrary kernel mappings. Support detection of such CPUs. Signed-off-by: Mikołaj Lenczewski <miko.lenczewski@xxxxxxx>
Reviewed-by: Suzuki K Poulose <suzuki.poulose@xxxxxxx>
