From 5d7abefcf84033dfa87717103e38e1eae44d8649 Mon Sep 17 00:00:00 2001 From: Jia He Date: Fri, 11 Oct 2019 22:09:36 +0800 Subject: [PATCH] BACKPORT: 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. Moto-CRs-Fixed:(CR) Link: https://lore.kernel.org/r/20191011140939.6115-2-justin.he@arm.com/ Change-Id: Ifed339bfe6c86ada6e45eddefa6aa010a7fe465d Signed-off-by: Jia He Suggested-by: Suzuki Poulose Reviewed-by: Catalin Marinas Signed-off-by: Catalin Marinas (cherry picked from commit 47d7b15b88f96a90694cfc607d0717d62dff6c45) Bug: 261052246 Signed-off-by: Kalesh Singh Reviewed-on: https://gerrit.mot.com/2491776 SME-Granted: SME Approvals Granted SLTApproved: Slta Waiver Tested-by: Jira Key Reviewed-by: Xiangpo Zhao Submit-Approved: Jira Key --- arch/arm64/include/asm/cpufeature.h | 13 +++++++++++++ 1 file changed, 13 insertions(+) diff --git a/arch/arm64/include/asm/cpufeature.h b/arch/arm64/include/asm/cpufeature.h index 95f661f1933f..74bc372ec016 100644 --- a/arch/arm64/include/asm/cpufeature.h +++ b/arch/arm64/include/asm/cpufeature.h @@ -707,6 +707,19 @@ static inline u32 id_aa64mmfr0_parange_to_phys_shift(int parange) extern bool cpu_has_amu_feat(int cpu); #endif +/* 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