On Tue, Feb 07, 2023 at 05:06:39PM +0000, Marc Zyngier wrote: > On Tue, 07 Feb 2023 16:40:05 +0000, > Tom Rini <tr...@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....@linaro.org> > > > > Signed-off-by: Marc Zyngier <m...@kernel.org> > > > > Signed-off-by: Will Deacon <willdea...@google.com> > > > > Cc: Tom Rini <tr...@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#attributing-code-copyrights-signing > > > > 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/+/db5507f47f4f57f766d52f753ff2cc761afc213b
Oh, hummm. I guess whatever the normal policy for upstreaming patches from an Android kernel tree, to mainline, would be the starting point here? Referencing the Android tree would be good too. -- Tom
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