On Tue, 07 Feb 2023 16:40:05 +0000, Tom Rini trini@konsulko.com wrote:
On Tue, Feb 07, 2023 at 04:35:25PM +0000, Marc Zyngier wrote:
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@linaro.org Signed-off-by: Marc Zyngier maz@kernel.org Signed-off-by: Will Deacon willdeacon@google.com Cc: Tom Rini trini@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?
As my first guess here is copy and adopting code from Linux, this is not following the documented procedure here: https://u-boot.readthedocs.io/en/latest/develop/sending_patches.html#attribu...
Which if not sufficiently clear, please ask / suggest changes to. I see right now it isn't specific about cc'ing the original authors (who may, or may not, be interested, so blanket policy doesn't apply) but I would hope is clear enough that what's done in this example isn't right.
No, this really is u-boot code written as part of Android, from where the patch has been directly lifted[1].
Same goes for Pierre-Clement's patch that is part of the same series.
I'm not overly attached to this code (I have bad memories from it), but I think the OP may be unaware of these rules. In any case, I'm supportive of this code making it in upstream u-boot. I just want it to be done correctly.
Thanks,
M.
[1] https://android.googlesource.com/platform/external/u-boot/+/db5507f47f4f57f7...