Messages in this thread Patch in this message | | | Date | Wed, 9 Dec 2020 18:35:09 +0000 | From | Catalin Marinas <> | Subject | Re: [PATCH 2/2] arm64: mm: Implement arch_wants_old_faultaround_pte() |
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On Wed, Dec 09, 2020 at 04:39:50PM +0000, Will Deacon wrote: > diff --git a/arch/arm64/include/asm/cpufeature.h b/arch/arm64/include/asm/cpufeature.h > index da250e4741bd..3424f5881390 100644 > --- a/arch/arm64/include/asm/cpufeature.h > +++ b/arch/arm64/include/asm/cpufeature.h > @@ -764,6 +764,18 @@ static inline bool cpu_has_hw_af(void) > ID_AA64MMFR1_HADBS_SHIFT); > } > > +static inline bool system_has_hw_af(void) > +{ > + u64 mmfr1; > + > + if (!IS_ENABLED(CONFIG_ARM64_HW_AFDBM)) > + return false; > + > + mmfr1 = read_sanitised_ftr_reg(SYS_ID_AA64MMFR1_EL1); > + return cpuid_feature_extract_unsigned_field(mmfr1, > + ID_AA64MMFR1_HADBS_SHIFT); > +}
Could we not add a new system-wide cpu feature that checks for hardware AF? This read_sanitised_ftr_reg() does a binary search on each invocation.
-- Catalin
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