Re: [PATCH v5 13/21] arm64: Allow ID_AA64MMFR1_EL1.VH to be overridden from the command line

[Marc Zyngier]

On 2021-01-25 13:15, Suzuki K Poulose wrote:
> On 1/25/21 10:50 AM, Marc Zyngier wrote:
> > As we want to be able to disable VHE at runtime, let's match
> > "id_aa64mmfr1.vh=" from the command line as an override.
> > This doesn't have much effect yet as our boot code doesn't look
> > at the cpufeature, but only at the HW registers.
> >
> > Signed-off-by: Marc Zyngier <maz@xxxxxxxxxx>
> > Acked-by: David Brazdil <dbrazdil@xxxxxxxxxx>
> > ---
> >   arch/arm64/include/asm/cpufeature.h |  2 ++
> >   arch/arm64/kernel/cpufeature.c      |  5 ++++-
> >   arch/arm64/kernel/idreg-override.c  | 11 +++++++++++
> >   3 files changed, 17 insertions(+), 1 deletion(-)
> >
> > diff --git a/arch/arm64/include/asm/cpufeature.h 
> > b/arch/arm64/include/asm/cpufeature.h
> > index 4179cfc8ed57..b0ed37da4067 100644
> > --- a/arch/arm64/include/asm/cpufeature.h
> > +++ b/arch/arm64/include/asm/cpufeature.h
> > @@ -818,6 +818,8 @@ static inline unsigned int get_vmid_bits(u64 
> > mmfr1)
> >   	return 8;
> >   }
> >   +extern struct arm64_ftr_override id_aa64mmfr1_override;
> > +
> >   u32 get_kvm_ipa_limit(void);
> >   void dump_cpu_features(void);
> >   diff --git a/arch/arm64/kernel/cpufeature.c 
> > b/arch/arm64/kernel/cpufeature.c
> > index 4b84a1e1dc51..c1d6712c4249 100644
> > --- a/arch/arm64/kernel/cpufeature.c
> > +++ b/arch/arm64/kernel/cpufeature.c
> > @@ -557,6 +557,8 @@ static const struct arm64_ftr_bits ftr_raz[] = {
> >     #define ARM64_FTR_REG(id, table) ARM64_FTR_REG_OVERRIDE(id, table, 
> > &no_override)
> >   +struct arm64_ftr_override id_aa64mmfr1_override;
>
> Does this need to be ro_after_init ?

Could do, together with the other two override targeting system 
registers.

> Otherwise, looks good to me:
>
> Acked-by: Suzuki K Poulose <suzuki.poulose@xxxxxxx>

Thanks,

        M.
--
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