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From: Catalin Marinas <catalin.marinas@arm.com>
To: Will Deacon <will@kernel.org>
Cc: linux-kernel@vger.kernel.org, linux-mm@kvack.org,
	linux-arm-kernel@lists.infradead.org, Jan Kara <jack@suse.cz>,
	Minchan Kim <minchan@kernel.org>,
	Andrew Morton <akpm@linux-foundation.org>,
	"Kirill A . Shutemov" <kirill.shutemov@linux.intel.com>,
	Linus Torvalds <torvalds@linux-foundation.org>,
	Vinayak Menon <vinmenon@codeaurora.org>,
	kernel-team@android.com
Subject: Re: [PATCH 2/2] arm64: mm: Implement arch_wants_old_faultaround_pte()
Date: Wed, 9 Dec 2020 18:35:09 +0000	[thread overview]
Message-ID: <20201209183509.GH13566@gaia> (raw)
In-Reply-To: <20201209163950.8494-3-will@kernel.org>

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

WARNING: multiple messages have this Message-ID (diff)
From: Catalin Marinas <catalin.marinas@arm.com>
To: Will Deacon <will@kernel.org>
Cc: Jan Kara <jack@suse.cz>, Minchan Kim <minchan@kernel.org>,
	kernel-team@android.com, linux-kernel@vger.kernel.org,
	linux-mm@kvack.org, Vinayak Menon <vinmenon@codeaurora.org>,
	"Kirill A . Shutemov" <kirill.shutemov@linux.intel.com>,
	Andrew Morton <akpm@linux-foundation.org>,
	Linus Torvalds <torvalds@linux-foundation.org>,
	linux-arm-kernel@lists.infradead.org
Subject: Re: [PATCH 2/2] arm64: mm: Implement arch_wants_old_faultaround_pte()
Date: Wed, 9 Dec 2020 18:35:09 +0000	[thread overview]
Message-ID: <20201209183509.GH13566@gaia> (raw)
In-Reply-To: <20201209163950.8494-3-will@kernel.org>

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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  reply	other threads:[~2020-12-09 18:35 UTC|newest]

Thread overview: 138+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-12-09 16:39 [PATCH 0/2] Create 'old' ptes for faultaround mappings on arm64 with hardware access flag Will Deacon
2020-12-09 16:39 ` Will Deacon
2020-12-09 16:39 ` [PATCH 1/2] mm: Allow architectures to request 'old' entries when prefaulting Will Deacon
2020-12-09 16:39   ` Will Deacon
2020-12-09 17:58   ` Linus Torvalds
2020-12-09 17:58     ` Linus Torvalds
2020-12-09 17:58     ` Linus Torvalds
2020-12-09 18:40     ` Will Deacon
2020-12-09 18:40       ` Will Deacon
2020-12-09 19:04       ` Linus Torvalds
2020-12-09 19:04         ` Linus Torvalds
2020-12-09 19:04         ` Linus Torvalds
2020-12-09 20:32         ` Matthew Wilcox
2020-12-09 20:32           ` Matthew Wilcox
2020-12-09 21:04           ` Linus Torvalds
2020-12-09 21:04             ` Linus Torvalds
2020-12-09 21:04             ` Linus Torvalds
2020-12-10 15:08         ` Kirill A. Shutemov
2020-12-10 15:08           ` Kirill A. Shutemov
2020-12-10 17:23           ` Linus Torvalds
2020-12-10 17:23             ` Linus Torvalds
2020-12-10 17:23             ` Linus Torvalds
2020-12-14 16:07             ` Kirill A. Shutemov
2020-12-14 16:07               ` Kirill A. Shutemov
2020-12-14 17:54               ` Linus Torvalds
2020-12-14 17:54                 ` Linus Torvalds
2020-12-14 17:54                 ` Linus Torvalds
2020-12-14 18:56                 ` Matthew Wilcox
2020-12-14 18:56                   ` Matthew Wilcox
2020-12-16 17:07                 ` Kirill A. Shutemov
2020-12-16 17:07                   ` Kirill A. Shutemov
2020-12-16 18:41                   ` Linus Torvalds
2020-12-16 18:41                     ` Linus Torvalds
2020-12-16 18:41                     ` Linus Torvalds
2020-12-17 10:54                     ` Kirill A. Shutemov
2020-12-17 10:54                       ` Kirill A. Shutemov
2020-12-17 18:22                       ` Linus Torvalds
2020-12-17 18:22                         ` Linus Torvalds
2020-12-17 18:22                         ` Linus Torvalds
2020-12-18 11:04                         ` Kirill A. Shutemov
2020-12-18 11:04                           ` Kirill A. Shutemov
2020-12-18 18:56                           ` Linus Torvalds
2020-12-18 18:56                             ` Linus Torvalds
2020-12-18 18:56                             ` Linus Torvalds
2020-12-19 12:41                             ` Kirill A. Shutemov
2020-12-19 12:41                               ` Kirill A. Shutemov
2020-12-19 20:08                               ` Linus Torvalds
2020-12-19 20:08                                 ` Linus Torvalds
2020-12-19 20:08                                 ` Linus Torvalds
2020-12-19 20:34                               ` Linus Torvalds
2020-12-19 20:34                                 ` Linus Torvalds
2020-12-19 20:34                                 ` Linus Torvalds
2020-12-22 10:00                                 ` Kirill A. Shutemov
2020-12-22 10:00                                   ` Kirill A. Shutemov
2020-12-24  4:04                                   ` Hugh Dickins
2020-12-24  4:04                                     ` Hugh Dickins
2020-12-24  4:04                                     ` Hugh Dickins
2020-12-25 11:31                                     ` Kirill A. Shutemov
2020-12-25 11:31                                       ` Kirill A. Shutemov
2020-12-26 17:57                                       ` Linus Torvalds
2020-12-26 17:57                                         ` Linus Torvalds
2020-12-26 17:57                                         ` Linus Torvalds
2020-12-26 20:43                                         ` Kirill A. Shutemov
2020-12-26 20:43                                           ` Kirill A. Shutemov
2020-12-26 21:03                                           ` Hugh Dickins
2020-12-26 21:03                                             ` Hugh Dickins
2020-12-26 21:03                                             ` Hugh Dickins
2020-12-26 21:16                                             ` Linus Torvalds
2020-12-26 21:16                                               ` Linus Torvalds
2020-12-26 21:16                                               ` Linus Torvalds
2020-12-26 22:40                                               ` Kirill A. Shutemov
2020-12-26 22:40                                                 ` Kirill A. Shutemov
2020-12-27  0:45                                                 ` Hugh Dickins
2020-12-27  0:45                                                   ` Hugh Dickins
2020-12-27  0:45                                                   ` Hugh Dickins
2020-12-27  2:38                                                   ` Hugh Dickins
2020-12-27  2:38                                                     ` Hugh Dickins
2020-12-27  2:38                                                     ` Hugh Dickins
2020-12-27 19:38                                                     ` Linus Torvalds
2020-12-27 19:38                                                       ` Linus Torvalds
2020-12-27 19:38                                                       ` Linus Torvalds
2020-12-27 20:32                                                       ` Damian Tometzki
2020-12-27 20:32                                                         ` Damian Tometzki
2020-12-27 22:35                                                         ` Hugh Dickins
2020-12-27 22:35                                                           ` Hugh Dickins
2020-12-27 22:35                                                           ` Hugh Dickins
2020-12-27 23:12                                                           ` Linus Torvalds
2020-12-27 23:12                                                             ` Linus Torvalds
2020-12-27 23:12                                                             ` Linus Torvalds
2020-12-27 23:40                                                             ` Linus Torvalds
2020-12-27 23:40                                                               ` Linus Torvalds
2020-12-27 23:40                                                               ` Linus Torvalds
2020-12-27 23:55                                                               ` Kirill A. Shutemov
2020-12-27 23:55                                                                 ` Kirill A. Shutemov
2020-12-27 23:48                                                       ` Kirill A. Shutemov
2020-12-27 23:48                                                         ` Kirill A. Shutemov
2020-12-28  1:54                                                         ` Linus Torvalds
2020-12-28  1:54                                                           ` Linus Torvalds
2020-12-28  1:54                                                           ` Linus Torvalds
2020-12-28  6:43                                                           ` Hugh Dickins
2020-12-28  6:43                                                             ` Hugh Dickins
2020-12-28  6:43                                                             ` Hugh Dickins
2020-12-28 12:53                                                             ` Kirill A. Shutemov
2020-12-28 12:53                                                               ` Kirill A. Shutemov
2020-12-28 18:47                                                               ` Linus Torvalds
2020-12-28 18:47                                                                 ` Linus Torvalds
2020-12-28 18:47                                                                 ` Linus Torvalds
2020-12-28 21:58                                                                 ` Linus Torvalds
2020-12-28 21:58                                                                   ` Linus Torvalds
2020-12-28 21:58                                                                   ` Linus Torvalds
2020-12-29 13:28                                                                   ` Kirill A. Shutemov
2020-12-29 13:28                                                                     ` Kirill A. Shutemov
2020-12-29 15:19                                                                     ` Matthew Wilcox
2020-12-29 15:19                                                                       ` Matthew Wilcox
2020-12-29 20:52                                                                     ` Linus Torvalds
2020-12-29 20:52                                                                       ` Linus Torvalds
2020-12-29 20:52                                                                       ` Linus Torvalds
2020-12-28 22:05                                                                 ` Kirill A. Shutemov
2020-12-28 22:05                                                                   ` Kirill A. Shutemov
2020-12-28 22:12                                                                   ` Kirill A. Shutemov
2020-12-28 22:12                                                                     ` Kirill A. Shutemov
2020-12-29  4:35                                                                     ` Hugh Dickins
2020-12-29  4:35                                                                       ` Hugh Dickins
2020-12-29  4:35                                                                       ` Hugh Dickins
2020-12-28 23:28                                                                   ` Linus Torvalds
2020-12-28 23:28                                                                     ` Linus Torvalds
2020-12-28 23:28                                                                     ` Linus Torvalds
2020-12-26 21:07                                           ` Linus Torvalds
2020-12-26 21:07                                             ` Linus Torvalds
2020-12-26 21:07                                             ` Linus Torvalds
2020-12-26 21:41                                           ` Matthew Wilcox
2020-12-26 21:41                                             ` Matthew Wilcox
2020-12-09 16:39 ` [PATCH 2/2] arm64: mm: Implement arch_wants_old_faultaround_pte() Will Deacon
2020-12-09 16:39   ` Will Deacon
2020-12-09 18:35   ` Catalin Marinas [this message]
2020-12-09 18:35     ` Catalin Marinas
2020-12-09 18:46     ` Will Deacon
2020-12-09 18:46       ` Will Deacon

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