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From: Jia He <justin.he@arm.com>
To: Catalin Marinas <catalin.marinas@arm.com>,
	Will Deacon <will@kernel.org>,
	Mark Rutland <mark.rutland@arm.com>,
	James Morse <james.morse@arm.com>, Marc Zyngier <maz@kernel.org>,
	Matthew Wilcox <willy@infradead.org>,
	"Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>,
	linux-arm-kernel@lists.infradead.org,
	linux-kernel@vger.kernel.org, linux-mm@kvack.org,
	Suzuki Poulose <Suzuki.Poulose@arm.com>,
	Borislav Petkov <bp@alien8.de>, "H. Peter Anvin" <hpa@zytor.com>,
	x86@kernel.org
Cc: Thomas Gleixner <tglx@linutronix.de>,
	Andrew Morton <akpm@linux-foundation.org>,
	hejianet@gmail.com, Kaly Xin <Kaly.Xin@arm.com>,
	nd@arm.com, Jia He <justin.he@arm.com>
Subject: [PATCH v11 1/4] arm64: cpufeature: introduce helper cpu_has_hw_af()
Date: Wed,  9 Oct 2019 16:42:43 +0800
Message-ID: <20191009084246.123354-2-justin.he@arm.com> (raw)
In-Reply-To: <20191009084246.123354-1-justin.he@arm.com>

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().

Signed-off-by: Jia He <justin.he@arm.com>
Suggested-by: Suzuki Poulose <Suzuki.Poulose@arm.com>
Reviewed-by: Catalin Marinas <catalin.marinas@arm.com>
---
 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 9cde5d2e768f..1a95396ea5c8 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)
+{
+	if (IS_ENABLED(CONFIG_ARM64_HW_AFDBM)) {
+		u64 mmfr1 = read_cpuid(ID_AA64MMFR1_EL1);
+
+		return !!cpuid_feature_extract_unsigned_field(mmfr1,
+						ID_AA64MMFR1_HADBS_SHIFT);
+	}
+
+	return false;
+}
+
 #endif /* __ASSEMBLY__ */
 
 #endif
-- 
2.17.1



  reply index

Thread overview: 10+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-10-09  8:42 [PATCH v11 0/4] fix double page fault in cow_user_page for pfn mapping Jia He
2019-10-09  8:42 ` Jia He [this message]
2019-10-10 16:43   ` [PATCH v11 1/4] arm64: cpufeature: introduce helper cpu_has_hw_af() Catalin Marinas
2019-10-11  1:16     ` Justin He (Arm Technology China)
2019-10-11 10:38       ` Catalin Marinas
2019-10-11 13:51         ` Justin He (Arm Technology China)
2019-10-09  8:42 ` [PATCH v11 2/4] arm64: mm: implement arch_faults_on_old_pte() on arm64 Jia He
2019-10-09  8:42 ` [PATCH v11 3/4] x86/mm: implement arch_faults_on_old_pte() stub on x86 Jia He
2019-10-09  8:42 ` [PATCH v11 4/4] mm: fix double page fault on arm64 if PTE_AF is cleared Jia He
2019-10-10 16:45   ` Catalin Marinas

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