Messages in this thread | | | Date | Mon, 23 Sep 2019 17:07:11 +0100 | From | Catalin Marinas <> | Subject | Re: [PATCH v8 1/3] arm64: cpufeature: introduce helper cpu_has_hw_af() |
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On Sat, Sep 21, 2019 at 09:50:52PM +0800, Jia He wrote: > We unconditionally set the HW_AFDBM capability and only enable it on > CPUs which really have the feature. But sometimes we need to know > whether this cpu has the capability of HW AF. So decouple AF from > DBM by new helper cpu_has_hw_af(). > > Reported-by: kbuild test robot <lkp@intel.com> > Suggested-by: Suzuki Poulose <Suzuki.Poulose@arm.com> > Signed-off-by: Jia He <justin.he@arm.com> > --- > arch/arm64/include/asm/cpufeature.h | 10 ++++++++++ > 1 file changed, 10 insertions(+) > > diff --git a/arch/arm64/include/asm/cpufeature.h b/arch/arm64/include/asm/cpufeature.h > index c96ffa4722d3..46caf934ba4e 100644 > --- a/arch/arm64/include/asm/cpufeature.h > +++ b/arch/arm64/include/asm/cpufeature.h > @@ -667,6 +667,16 @@ static inline u32 id_aa64mmfr0_parange_to_phys_shift(int parange) > default: return CONFIG_ARM64_PA_BITS; > } > } > + > +/* Decouple AF from AFDBM. */
We could do with a better comment here or just remove it altogether. The aim of the patch was to decouple AF check from the AF+DBM but the comment here should describe what the function does. Maybe something like: "Check whether hardware update of the Access flag is supported".
> +static inline bool cpu_has_hw_af(void) > +{ > + if (IS_ENABLED(CONFIG_ARM64_HW_AFDBM)) > + return read_cpuid(ID_AA64MMFR1_EL1) & 0xf; > + > + return false; > +}
Other than the comment above,
Reviewed-by: Catalin Marinas <catalin.marinas@arm.com>
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