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

Marc Zyngier maz at kernel.org
Tue Feb 7 17:35:25 CET 2023

On 2023-02-07 16:20, Ying-Chun Liu (PaulLiu) wrote:
> 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: Ying-Chun Liu (PaulLiu) <paul.liu at linaro.org>
> Signed-off-by: Marc Zyngier <maz at kernel.org>
> Signed-off-by: Will Deacon <willdeacon at google.com>
> Cc: Tom Rini <trini at konsulko.com>

The sign-off chain looks pretty odd. Either you are the author
of this patch, and I have nothing to do on the sign-off list,
or I'm the author and the authorship is wrong. Similar things
would apply for Will.

So which one is it?

Jazz is not dead. It just smells funny...

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