Subject: Re: powerpc/powernv: Fix boot on Power8 bare metal due to opal_configure_cores()

From: Michael Ellerman <[email-masked]>
Date: Tue, 18 Jul 2017 20:26:12 +1000 (AEST)

On Mon, 2017-07-17 at 11:31:00 UTC, Michael Ellerman wrote:
> In commit 1c0eaf0f56d6 ("powerpc/powernv: Tell OPAL about our MMU mode
> on POWER9"), we added additional flags to the OPAL call to configure
> CPUs at boot.
> 
> These flags only work on Power9 firmwares, and worse can cause boot
> failures on Power8 machines, so we check for CPU_FTR_ARCH_300 (aka POWER9)
> before adding the extra flags.
> 
> Unfortunately we forgot that opal_configure_cores() is called before
> the CPU feature checks are dynamically patched, meaning the check
> always returns true.
> 
> We definitely need to do something to make the CPU feature checks less
> prone to bugs like this, but for now the minimal fix is to use
> early_cpu_has_feature().
> 
> Reported-and-tested-by: Abdul Haleem <[email-masked]>
> Fixes: 1c0eaf0f56d6 ("powerpc/powernv: Tell OPAL about our MMU mode on POWER9")
> Signed-off-by: Michael Ellerman <[email-masked]>
> Acked-by: Balbir Singh <[email-masked]>

Applied to powerpc fixes.

https://git.kernel.org/powerpc/c/a70b487b07cf4201bc6702e7f646fa

cheers