[PATCH v2 1/2] arm: cpu: Add optional CMOs by VA

[Tom Rini]

On Thu, Feb 09, 2023 at 04:54:27AM +0800, Ying-Chun Liu (PaulLiu) wrote:

> From: Marc Zyngier <maz at kernel.org>
> 
> Exposing set/way cache maintenance to a virtual machine is unsafe, not
> least because the instructions are not permission-checked but also
> because they are not broadcast between CPUs. Consequently, KVM traps and
> emulates such maintenance in the host kernel using by-VA operations and
> looping over the stage-2 page-tables. However, when running under
> protected KVM, these instructions are not able to be emulated and will
> instead result in an exception being delivered to the guest.
> 
> Introduce CONFIG_CMO_BY_VA_ONLY so that virtual platforms can select
> this option and perform by-VA cache maintenance instead of using the
> set/way instructions.
> 
> Signed-off-by: Marc Zyngier <maz at kernel.org>
> Signed-off-by: Will Deacon <willdeacon at google.com>
> Signed-off-by: Pierre-Clément Tosi <ptosi at google.com>
> [ Paul: pick from the Android tree. Fixup Pierre's commit. And fix some
>   checkpatch warnings. Rebased to upstream. ]
> Signed-off-by: Ying-Chun Liu (PaulLiu) <paul.liu at linaro.org>
> Cc: Tom Rini <trini at konsulko.com>
> Link: https://android.googlesource.com/platform/external/u-boot/+/db5507f47f4f57f766d52f753ff2cc761afc213b
> Link: https://android.googlesource.com/platform/external/u-boot/+/2baf54e743380a1e4a6bc2dbdde020a2e783ff67

Applied to u-boot/next, thanks!

-- 
Tom
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