From: Catalin Marinas <catalin.marinas@arm•com>
To: Jia He <justin.he@arm•com>
Cc: "Mark Rutland" <mark.rutland@arm•com>,
"Kaly Xin" <Kaly.Xin@arm•com>,
"Ralph Campbell" <rcampbell@nvidia•com>,
"Andrew Morton" <akpm@linux-foundation•org>,
"Suzuki Poulose" <Suzuki.Poulose@arm•com>,
"Marc Zyngier" <maz@kernel•org>,
"Anshuman Khandual" <anshuman.khandual@arm•com>,
linux-kernel@vger•kernel.org,
"Matthew Wilcox" <willy@infradead•org>,
linux-mm@kvack•org, "Jérôme Glisse" <jglisse@redhat•com>,
"James Morse" <james.morse@arm•com>,
linux-arm-kernel@lists•infradead.org,
"Punit Agrawal" <punitagrawal@gmail•com>,
hejianet@gmail•com, "Thomas Gleixner" <tglx@linutronix•de>,
nd@arm•com, "Will Deacon" <will@kernel•org>,
"Alex Van Brunt" <avanbrunt@nvidia•com>,
"Kirill A. Shutemov" <kirill.shutemov@linux•intel.com>,
"Robin Murphy" <robin.murphy@arm•com>
Subject: Re: [PATCH v8 1/3] arm64: cpufeature: introduce helper cpu_has_hw_af()
Date: Mon, 23 Sep 2019 17:07:11 +0100 [thread overview]
Message-ID: <20190923160710.GC10192@arrakis.emea.arm.com> (raw)
In-Reply-To: <20190921135054.142360-2-justin.he@arm.com>
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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next prev parent reply other threads:[~2019-09-23 16:07 UTC|newest]
Thread overview: 16+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-09-21 13:50 [PATCH v8 0/3] fix double page fault on arm64 Jia He
2019-09-21 13:50 ` [PATCH v8 1/3] arm64: cpufeature: introduce helper cpu_has_hw_af() Jia He
2019-09-23 16:07 ` Catalin Marinas [this message]
2019-09-24 1:50 ` Justin He (Arm Technology China)
2019-09-21 13:50 ` [PATCH v8 2/3] arm64: mm: implement arch_faults_on_old_pte() on arm64 Jia He
2019-09-23 16:18 ` Catalin Marinas
2019-09-24 2:17 ` Justin He (Arm Technology China)
2019-09-21 13:50 ` [PATCH v8 3/3] mm: fix double page fault on arm64 if PTE_AF is cleared Jia He
2019-09-21 15:31 ` Matthew Wilcox
2019-09-23 8:28 ` Kirill A. Shutemov
2019-09-23 17:04 ` Catalin Marinas
2019-09-24 6:43 ` Justin He (Arm Technology China)
2019-09-24 10:33 ` Catalin Marinas
2019-09-24 11:59 ` Kirill A. Shutemov
2019-09-24 15:29 ` Jia He
2019-09-24 16:35 ` Catalin Marinas
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