[PATCH v1 1/2] aarch64: enable access to TCR2_ELx

[Joey Gouly]

Hi,

On Thu, Jun 15, 2023 at 04:21:06PM +0100, Mark Rutland wrote:
> On Fri, Mar 10, 2023 at 05:36:56PM +0000, Joey Gouly wrote:
> > Allow access the TCR2_ELx register which provides extended translation
> > controls similar to TCR_ELx.
> 
> AFAICT TCR2_ELx reset to UNKNOWN values, and existing EL{2,1} software won't
> know that TCR2_ELx exists. So either:
> 
> (a) The bootwrapper needs to initialize TCR2_ELx to some sane value to avoid
>     subsequent problems.
> 
> (b) The TCR2_ELx bits are gated by some existing RESx bit that EL{2,1} will
>     configure (e.g. only apply after setting some existing TCR_ELx or SCTLR_Elx
>     bit).
> 
> I suspect that we fall into case (a), but I don't see any initialization of
> TCR2_ELx.

You're right, I will intialise it (to 0, seems like the right thing to do looking 
at the definition) and send out a new series (along with the other fix).
> 
> Do we need to add initiailization, or does case (b) apply? If it's the latter,
> could we please add something to the commit message describing that?

Looks like HCRX_EL2 is also missing initialisation.

> 
> Other than that, this looks fine to me.

Thanks,
Joey