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From: Catalin Marinas <catalin.marinas@arm.com>
To: Anshuman Khandual <anshuman.khandual@arm.com>
Cc: linux-arm-kernel@lists.infradead.org,
	linux-kernel@vger.kernel.org, linux-mm@kvack.org,
	akpm@linux-foundation.org, suzuki.poulose@arm.com,
	mark.rutland@arm.com, will@kernel.org, maz@kernel.org,
	james.morse@arm.com, steven.price@arm.com
Subject: Re: [RFC V2 05/10] arm64/mm: Add CONFIG_ARM64_PA_BITS_52_[LPA|LPA2]
Date: Thu, 5 Aug 2021 18:25:50 +0100	[thread overview]
Message-ID: <20210805172550.GG6719@arm.com> (raw)
In-Reply-To: <1627281445-12445-6-git-send-email-anshuman.khandual@arm.com>

On Mon, Jul 26, 2021 at 12:07:20PM +0530, Anshuman Khandual wrote:
> diff --git a/arch/arm64/Kconfig b/arch/arm64/Kconfig
> index b5b13a9..1999ac6 100644
> --- a/arch/arm64/Kconfig
> +++ b/arch/arm64/Kconfig
> @@ -934,6 +934,12 @@ config ARM64_VA_BITS
>  	default 48 if ARM64_VA_BITS_48
>  	default 52 if ARM64_VA_BITS_52
>  
> +config ARM64_PA_BITS_52_LPA
> +	bool
> +
> +config ARM64_PA_BITS_52_LPA2
> +	bool
> +
>  choice
>  	prompt "Physical address space size"
>  	default ARM64_PA_BITS_48
> @@ -948,6 +954,7 @@ config ARM64_PA_BITS_52
>  	bool "52-bit (ARMv8.2)"
>  	depends on ARM64_64K_PAGES
>  	depends on ARM64_PAN || !ARM64_SW_TTBR0_PAN
> +	select ARM64_PA_BITS_52_LPA if ARM64_64K_PAGES
>  	help
>  	  Enable support for a 52-bit physical address space, introduced as
>  	  part of the ARMv8.2-LPA extension.

Do we actually need to bother with LPA, LPA2 options? We could just add
an extra defined(ARM64_64K_PAGES) in places, it may be easier to follow
in a few years time when we won't remember what LPA or LPA2 was. I
haven't got to the rest of the patches but it may just be simpler to
define the shifts separately for 52-bit based on 4K/16K/64K and ignore
the LPA/LPA2 distinction altogether (we'll still keep it for CPUID
checking though).

-- 
Catalin

WARNING: multiple messages have this Message-ID (diff)
From: Catalin Marinas <catalin.marinas@arm.com>
To: Anshuman Khandual <anshuman.khandual@arm.com>
Cc: linux-arm-kernel@lists.infradead.org,
	linux-kernel@vger.kernel.org, linux-mm@kvack.org,
	akpm@linux-foundation.org, suzuki.poulose@arm.com,
	mark.rutland@arm.com, will@kernel.org, maz@kernel.org,
	james.morse@arm.com, steven.price@arm.com
Subject: Re: [RFC V2 05/10] arm64/mm: Add CONFIG_ARM64_PA_BITS_52_[LPA|LPA2]
Date: Thu, 5 Aug 2021 18:25:50 +0100	[thread overview]
Message-ID: <20210805172550.GG6719@arm.com> (raw)
In-Reply-To: <1627281445-12445-6-git-send-email-anshuman.khandual@arm.com>

On Mon, Jul 26, 2021 at 12:07:20PM +0530, Anshuman Khandual wrote:
> diff --git a/arch/arm64/Kconfig b/arch/arm64/Kconfig
> index b5b13a9..1999ac6 100644
> --- a/arch/arm64/Kconfig
> +++ b/arch/arm64/Kconfig
> @@ -934,6 +934,12 @@ config ARM64_VA_BITS
>  	default 48 if ARM64_VA_BITS_48
>  	default 52 if ARM64_VA_BITS_52
>  
> +config ARM64_PA_BITS_52_LPA
> +	bool
> +
> +config ARM64_PA_BITS_52_LPA2
> +	bool
> +
>  choice
>  	prompt "Physical address space size"
>  	default ARM64_PA_BITS_48
> @@ -948,6 +954,7 @@ config ARM64_PA_BITS_52
>  	bool "52-bit (ARMv8.2)"
>  	depends on ARM64_64K_PAGES
>  	depends on ARM64_PAN || !ARM64_SW_TTBR0_PAN
> +	select ARM64_PA_BITS_52_LPA if ARM64_64K_PAGES
>  	help
>  	  Enable support for a 52-bit physical address space, introduced as
>  	  part of the ARMv8.2-LPA extension.

Do we actually need to bother with LPA, LPA2 options? We could just add
an extra defined(ARM64_64K_PAGES) in places, it may be easier to follow
in a few years time when we won't remember what LPA or LPA2 was. I
haven't got to the rest of the patches but it may just be simpler to
define the shifts separately for 52-bit based on 4K/16K/64K and ignore
the LPA/LPA2 distinction altogether (we'll still keep it for CPUID
checking though).

-- 
Catalin

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  reply	other threads:[~2021-08-05 17:26 UTC|newest]

Thread overview: 42+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-07-26  6:37 [RFC V2 00/10] arm64/mm: Enable FEAT_LPA2 (52 bits PA support on 4K|16K pages) Anshuman Khandual
2021-07-26  6:37 ` Anshuman Khandual
2021-07-26  6:37 ` [RFC V2 01/10] mm/mmap: Dynamically initialize protection_map[] Anshuman Khandual
2021-07-26  6:37   ` Anshuman Khandual
2021-08-05 17:03   ` Catalin Marinas
2021-08-05 17:03     ` Catalin Marinas
2021-08-12  9:15     ` Anshuman Khandual
2021-08-12  9:15       ` Anshuman Khandual
2021-08-13  7:16       ` Anshuman Khandual
2021-08-13  7:16         ` Anshuman Khandual
2021-07-26  6:37 ` [RFC V2 02/10] arm64/mm: Consolidate TCR_EL1 fields Anshuman Khandual
2021-07-26  6:37   ` Anshuman Khandual
2021-08-05 17:05   ` Catalin Marinas
2021-08-05 17:05     ` Catalin Marinas
2021-07-26  6:37 ` [RFC V2 03/10] arm64/mm: Add FEAT_LPA2 specific TCR_EL1.DS field Anshuman Khandual
2021-07-26  6:37   ` Anshuman Khandual
2021-08-05 17:06   ` Catalin Marinas
2021-08-05 17:06     ` Catalin Marinas
2021-07-26  6:37 ` [RFC V2 04/10] arm64/mm: Add FEAT_LPA2 specific ID_AA64MMFR0.TGRAN[2] Anshuman Khandual
2021-07-26  6:37   ` Anshuman Khandual
2021-08-05 17:06   ` Catalin Marinas
2021-08-05 17:06     ` Catalin Marinas
2021-07-26  6:37 ` [RFC V2 05/10] arm64/mm: Add CONFIG_ARM64_PA_BITS_52_[LPA|LPA2] Anshuman Khandual
2021-07-26  6:37   ` Anshuman Khandual
2021-08-05 17:25   ` Catalin Marinas [this message]
2021-08-05 17:25     ` Catalin Marinas
2021-08-12 10:09     ` Anshuman Khandual
2021-08-12 10:09       ` Anshuman Khandual
2021-07-26  6:37 ` [RFC V2 06/10] arm64/mm: Add FEAT_LPA2 specific encoding Anshuman Khandual
2021-07-26  6:37   ` Anshuman Khandual
2021-07-26  6:37 ` [RFC V2 07/10] arm64/mm: Detect and enable FEAT_LPA2 Anshuman Khandual
2021-07-26  6:37   ` Anshuman Khandual
2021-07-26  6:37 ` [RFC V2 08/10] arm64/mm: Add FEAT_LPA2 specific PTE_SHARED and PMD_SECT_S Anshuman Khandual
2021-07-26  6:37   ` Anshuman Khandual
2021-07-26  6:37 ` [RFC V2 09/10] arm64/mm: Add FEAT_LPA2 specific fallback (48 bits PA) when not implemented Anshuman Khandual
2021-07-26  6:37   ` Anshuman Khandual
2021-07-26  6:37 ` [RFC V2 10/10] arm64/mm: Enable CONFIG_ARM64_PA_BITS_52 on CONFIG_ARM64_[4K|16K]_PAGES Anshuman Khandual
2021-07-26  6:37   ` Anshuman Khandual
2021-08-05 17:23   ` Catalin Marinas
2021-08-05 17:23     ` Catalin Marinas
2021-08-12  9:13     ` Anshuman Khandual
2021-08-12  9:13       ` Anshuman Khandual

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