From: Christophe Leroy <christophe.leroy@c-s.fr>
To: Russell King - ARM Linux admin <linux@armlinux.org.uk>,
Mike Rapoport <rppt@kernel.org>
Cc: linux-kernel@vger.kernel.org,
Andrew Morton <akpm@linux-foundation.org>,
Arnd Bergmann <arnd@arndb.de>,
Benjamin Herrenschmidt <benh@kernel.crashing.org>,
Brian Cain <bcain@codeaurora.org>,
Catalin Marinas <catalin.marinas@arm.com>,
Fenghua Yu <fenghua.yu@intel.com>,
Geert Uytterhoeven <geert+renesas@glider.be>,
Guan Xuetao <gxt@pku.edu.cn>, James Morse <james.morse@arm.com>,
Jonas Bonn <jonas@southpole.se>,
Julien Thierry <julien.thierry.kdev@gmail.com>,
Ley Foon Tan <ley.foon.tan@intel.com>,
Marc Zyngier <maz@kernel.org>,
Michael Ellerman <mpe@ellerman.id.au>,
Paul Mackerras <paulus@samba.org>, Rich Felker <dalias@libc.org>,
Stafford Horne <shorne@gmail.com>,
Stefan Kristiansson <stefan.kristiansson@saunalahti.fi>,
Suzuki K Poulose <suzuki.poulose@arm.com>,
Tony Luck <tony.luck@intel.com>, Will Deacon <will@kernel.org>,
Yoshinori Sato <ysato@users.sourceforge.jp>,
kvmarm@lists.cs.columbia.edu, kvm-ppc@vger.kernel.org,
linux-arch@vger.kernel.org, linux-arm-kernel@lists.infradead.org,
linux-hexagon@vger.kernel.org, linux-ia64@vger.kernel.org,
linux-mm@kvack.org, linuxppc-dev@lists.ozlabs.org,
linux-sh@vger.kernel.org, nios2-dev@lists.rocketboards.org,
openrisc@lists.librecores.org,
uclinux-h8-devel@lists.sourceforge.jp,
Mike Rapoport <rppt@linux.ibm.com>
Subject: Re: [PATCH v2 00/13] mm: remove __ARCH_HAS_5LEVEL_HACK
Date: Sun, 16 Feb 2020 11:45:59 +0100 [thread overview]
Message-ID: <d6691709-30ce-4d28-0b7b-34f1fa3b4e6f@c-s.fr> (raw)
In-Reply-To: <20200216082230.GV25745@shell.armlinux.org.uk>
Le 16/02/2020 à 09:22, Russell King - ARM Linux admin a écrit :
> On Sun, Feb 16, 2020 at 10:18:30AM +0200, Mike Rapoport wrote:
>> From: Mike Rapoport <rppt@linux.ibm.com>
>>
>> Hi,
>>
>> These patches convert several architectures to use page table folding and
>> remove __ARCH_HAS_5LEVEL_HACK along with include/asm-generic/5level-fixup.h.
>>
>> The changes are mostly about mechanical replacement of pgd accessors with p4d
>> ones and the addition of higher levels to page table traversals.
>>
>> All the patches were sent separately to the respective arch lists and
>> maintainers hence the "v2" prefix.
>
> You fail to explain why this change which adds 488 additional lines of
> code is desirable.
>
The purpose of the series, ie droping a HACK, is worth it.
However looking at the powerpc patch I have the feeling that this series
goes behind its purpose.
The number additional lines could be deeply reduced I think if we limit
the patches to the strict minimum, ie just do things like below instead
of adding lots of handling of useless levels.
Instead of doing things like:
- pud = NULL;
+ p4d = NULL;
if (pgd_present(*pgd))
- pud = pud_offset(pgd, gpa);
+ p4d = p4d_offset(pgd, gpa);
+ else
+ new_p4d = p4d_alloc_one(kvm->mm, gpa);
+
+ pud = NULL;
+ if (p4d_present(*p4d))
+ pud = pud_offset(p4d, gpa);
else
new_pud = pud_alloc_one(kvm->mm, gpa);
It could be limited to:
if (pgd_present(*pgd))
- pud = pud_offset(pgd, gpa);
+ pud = pud_offset(p4d_offset(pgd, gpa), gpa);
else
new_pud = pud_alloc_one(kvm->mm, gpa);
Christophe
next prev parent reply other threads:[~2020-02-16 10:46 UTC|newest]
Thread overview: 25+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-02-16 8:18 [PATCH v2 00/13] mm: remove __ARCH_HAS_5LEVEL_HACK Mike Rapoport
2020-02-16 8:18 ` [PATCH v2 01/13] arm/arm64: add support for folded p4d page tables Mike Rapoport
2020-02-16 8:18 ` [PATCH v2 02/13] h8300: remove usage of __ARCH_USE_5LEVEL_HACK Mike Rapoport
2020-02-16 8:18 ` [PATCH v2 03/13] hexagon: remove __ARCH_USE_5LEVEL_HACK Mike Rapoport
2020-02-16 8:18 ` [PATCH v2 04/13] ia64: add support for folded p4d page tables Mike Rapoport
2020-02-16 8:18 ` [PATCH v2 05/13] nios2: " Mike Rapoport
2020-02-16 8:18 ` [PATCH v2 06/13] openrisc: " Mike Rapoport
2020-02-16 8:18 ` [PATCH v2 07/13] powerpc: " Mike Rapoport
2020-02-16 10:41 ` Christophe Leroy
2020-02-18 10:54 ` Mike Rapoport
2020-02-26 9:13 ` Mike Rapoport
2020-02-26 9:46 ` Christophe Leroy
2020-02-26 10:56 ` Mike Rapoport
2020-02-26 11:20 ` Christophe Leroy
2020-02-19 12:07 ` Christophe Leroy
2020-02-19 13:24 ` Mike Rapoport
2020-02-16 8:18 ` [PATCH v2 08/13] sh: fault: Modernize printing of kernel messages Mike Rapoport
2020-02-16 8:18 ` [PATCH v2 09/13] sh: drop __pXd_offset() macros that duplicate pXd_index() ones Mike Rapoport
2020-02-16 8:18 ` [PATCH v2 10/13] sh: add support for folded p4d page tables Mike Rapoport
2020-02-16 8:18 ` [PATCH v2 11/13] unicore32: remove __ARCH_USE_5LEVEL_HACK Mike Rapoport
2020-02-16 8:18 ` [PATCH v2 12/13] asm-generic: remove pgtable-nop4d-hack.h Mike Rapoport
2020-02-16 8:18 ` [PATCH v2 13/13] mm: remove __ARCH_HAS_5LEVEL_HACK and include/asm-generic/5level-fixup.h Mike Rapoport
2020-02-16 8:22 ` [PATCH v2 00/13] mm: remove __ARCH_HAS_5LEVEL_HACK Russell King - ARM Linux admin
2020-02-16 10:45 ` Christophe Leroy [this message]
2020-02-17 6:23 ` Mike Rapoport
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