Re: [PATCH 3/8] arm64: cpufeature: Add CPU capability for AArch32 EL1 support

[Will Deacon]

Hi Marc,

On Wed, Apr 15, 2020 at 09:55:57AM +0100, Marc Zyngier wrote:
> On 2020-04-14 22:31, Will Deacon wrote:
> > Although we emit a "SANITY CHECK" warning and taint the kernel if we
> > detect a CPU mismatch for AArch32 support at EL1, we still online the
> > CPU with disastrous consequences for any running 32-bit VMs.
> > 
> > Introduce a capability for AArch32 support at EL1 so that late onlining
> > of incompatible CPUs is forbidden.
> > 
> > Signed-off-by: Will Deacon <will@xxxxxxxxxx>
> 
> Definitely an improvement over the current situation, as the direct read
> of ID_AA64PFR0 was always a bit dodgy. Given that I'm pretty sure these new
> braindead SoCs are going to run an older version of the kernel, should we
> Cc stable for this?

I don't think there's a real need for -stable given that we do at least
taint the kernel. That's likely to annoy vendors enough to backport this
themselves ;)

Will