From 47d7b15b88f96a90694cfc607d0717d62dff6c45 Mon Sep 17 00:00:00 2001 From: Jia He Date: Fri, 11 Oct 2019 22:09:36 +0800 Subject: [PATCH] arm64: cpufeature: introduce helper cpu_has_hw_af() 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 a new helper cpu_has_hw_af(). If later we noticed a potential performance issue on this path, we can turn it into a static label as with other CPU features. Signed-off-by: Jia He Suggested-by: Suzuki Poulose Reviewed-by: Catalin Marinas Signed-off-by: Catalin Marinas --- arch/arm64/include/asm/cpufeature.h | 14 ++++++++++++++ 1 file changed, 14 insertions(+) diff --git a/arch/arm64/include/asm/cpufeature.h b/arch/arm64/include/asm/cpufeature.h index 9cde5d2..4261d55 100644 --- a/arch/arm64/include/asm/cpufeature.h +++ b/arch/arm64/include/asm/cpufeature.h @@ -659,6 +659,20 @@ static inline u32 id_aa64mmfr0_parange_to_phys_shift(int parange) default: return CONFIG_ARM64_PA_BITS; } } + +/* Check whether hardware update of the Access flag is supported */ +static inline bool cpu_has_hw_af(void) +{ + u64 mmfr1; + + if (!IS_ENABLED(CONFIG_ARM64_HW_AFDBM)) + return false; + + mmfr1 = read_cpuid(ID_AA64MMFR1_EL1); + return cpuid_feature_extract_unsigned_field(mmfr1, + ID_AA64MMFR1_HADBS_SHIFT); +} + #endif /* __ASSEMBLY__ */ #endif -- 2.7.4