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From: Steven Price <steven.price@arm.com>
To: "Luck, Tony" <tony.luck@intel.com>
Cc: "Mark Rutland" <Mark.Rutland@arm.com>,
	linux-ia64@vger.kernel.org,
	"Peter Zijlstra" <peterz@infradead.org>,
	"Catalin Marinas" <catalin.marinas@arm.com>,
	"Dave Hansen" <dave.hansen@linux.intel.com>,
	"Will Deacon" <will.deacon@arm.com>,
	linux-mm@kvack.org, "H. Peter Anvin" <hpa@zytor.com>,
	"Liang, Kan" <kan.liang@linux.intel.com>,
	x86@kernel.org, "Ingo Molnar" <mingo@redhat.com>,
	"Fenghua Yu" <fenghua.yu@intel.com>,
	"Arnd Bergmann" <arnd@arndb.de>,
	"Jérôme Glisse" <jglisse@redhat.com>,
	"Borislav Petkov" <bp@alien8.de>,
	"Andy Lutomirski" <luto@kernel.org>,
	"Kirill A. Shutemov" <kirill@shutemov.name>,
	"Thomas Gleixner" <tglx@linutronix.de>,
	linux-arm-kernel@lists.infradead.org,
	"Ard Biesheuvel" <ard.biesheuvel@linaro.org>,
	linux-kernel@vger.kernel.org, "James Morse" <james.morse@arm.com>
Subject: Re: [PATCH v3 08/34] ia64: mm: Add p?d_large() definitions
Date: Wed, 6 Mar 2019 13:45:07 +0000	[thread overview]
Message-ID: <aab0ac18-fe3b-a753-009e-8704edb15623@arm.com> (raw)
In-Reply-To: <20190304190637.GA13947@agluck-desk>

On 04/03/2019 19:06, Luck, Tony wrote:
> On Mon, Mar 04, 2019 at 01:16:47PM +0000, Steven Price wrote:
>> On 01/03/2019 21:57, Kirill A. Shutemov wrote:
>>> On Wed, Feb 27, 2019 at 05:05:42PM +0000, Steven Price wrote:
>>>> walk_page_range() is going to be allowed to walk page tables other than
>>>> those of user space. For this it needs to know when it has reached a
>>>> 'leaf' entry in the page tables. This information is provided by the
>>>> p?d_large() functions/macros.
>>>>
>>>> For ia64 leaf entries are always at the lowest level, so implement
>>>> stubs returning 0.
>>>
>>> Are you sure about this? I see pte_mkhuge defined for ia64 and Kconfig
>>> contains hugetlb references.
>>>
>>
>> I'm not completely familiar with ia64, but my understanding is that it
>> doesn't have the situation where a page table walk ends early - there is
>> always the full depth of entries. The p?d_huge() functions always return 0.
>>
>> However my understanding is that it does support huge TLB entries, so
>> when populating the TLB a region larger than a standard page can be mapped.
>>
>> I'd definitely welcome review by someone more familiar with ia64 to
>> check my assumptions.
> 
> ia64 has several ways to manage page tables. The one
> used by Linux has multi-level table walks like other
> architectures, but we don't allow mixing of different
> page sizes within a "region" (there are eight regions
> selected by the high 3 bits of the virtual address).

I'd gathered ia64 has this "region" concept, from what I can tell the
existing p?d_present() etc macros are assuming a particular
configuration of a region, and so the p?d_large macros would follow that
scheme. This of course does limit any generic page walking code to
dealing only with this one type of region, but that doesn't seem
unreasonable.

> Is the series in some GIT tree that I can pull, rather
> than tracking down all 34 pieces?  I can try it out and
> see if things work/break.

At the moment I don't have a public tree - I'm trying to get that set
up. In the meantime you can download the entire series as a mbox from
patchwork:

https://patchwork.kernel.org/series/85673/mbox/

(it's currently based on v5.0-rc6)

However you won't see anything particularly interesting on ia64 (yet)
because my focus has been converting the PTDUMP implementations that
several architecture have (arm, arm64, powerpc, s390, x86) but not ia64.
For now I've also only done the PTDUMP work for arm64/x86 as a way of
testing out the idea. Ideally the PTDUMP code can be made generic enough
that implementing it for other architecture (including ia64) will be
trivial.

Thanks,

Steve

  reply	other threads:[~2019-03-06 13:45 UTC|newest]

Thread overview: 68+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-02-27 17:05 [PATCH v3 00/34] Convert x86 & arm64 to use generic page walk Steven Price
2019-02-27 17:05 ` [PATCH v3 01/34] alpha: mm: Add p?d_large() definitions Steven Price
2019-02-27 17:05 ` [PATCH v3 02/34] arc: " Steven Price
2019-02-27 18:18   ` Vineet Gupta
2019-02-27 17:05 ` [PATCH v3 03/34] arm: " Steven Price
2019-03-01 21:47   ` Kirill A. Shutemov
2019-03-04 11:56     ` Steven Price
2019-03-04 13:10       ` Kirill A. Shutemov
2019-02-27 17:05 ` [PATCH v3 04/34] arm64: " Steven Price
2019-02-27 17:05 ` [PATCH v3 05/34] c6x: " Steven Price
2019-03-01 21:48   ` Kirill A. Shutemov
2019-03-04 12:01     ` Steven Price
2019-03-04 13:11       ` Kirill A. Shutemov
2019-02-27 17:05 ` [PATCH v3 06/34] csky: " Steven Price
2019-03-01 21:51   ` Kirill A. Shutemov
2019-02-27 17:05 ` [PATCH v3 07/34] hexagon: " Steven Price
2019-02-27 17:05 ` [PATCH v3 08/34] ia64: " Steven Price
2019-03-01 21:57   ` Kirill A. Shutemov
2019-03-04 13:16     ` Steven Price
2019-03-04 19:06       ` Luck, Tony
2019-03-06 13:45         ` Steven Price [this message]
2019-02-27 17:05 ` [PATCH v3 09/34] m68k: " Steven Price
2019-02-27 19:27   ` Geert Uytterhoeven
2019-02-28 11:36     ` Mike Rapoport
2019-02-28 11:53       ` Geert Uytterhoeven
2019-02-28 12:04         ` Steven Price
2019-03-01 11:45           ` Mike Rapoport
2019-02-27 17:05 ` [PATCH v3 10/34] microblaze: " Steven Price
2019-02-27 17:05 ` [PATCH v3 11/34] mips: " Steven Price
2019-02-28  2:15   ` Paul Burton
2019-02-28 12:11     ` Steven Price
2019-02-28 18:55       ` Paul Burton
2019-03-01 11:02         ` Steven Price
2019-02-27 17:05 ` [PATCH v3 12/34] nds32: " Steven Price
2019-02-27 17:05 ` [PATCH v3 13/34] nios2: " Steven Price
2019-02-27 17:05 ` [PATCH v3 14/34] openrisc: " Steven Price
2019-02-27 17:05 ` [PATCH v3 15/34] parisc: " Steven Price
2019-02-27 18:54   ` Helge Deller
2019-03-01 22:12     ` Kirill A. Shutemov
2019-03-05 21:45       ` Helge Deller
2019-02-27 17:05 ` [PATCH v3 16/34] powerpc: " Steven Price
2019-02-27 17:05 ` [PATCH v3 17/34] riscv: " Steven Price
2019-02-27 17:05 ` [PATCH v3 18/34] s390: " Steven Price
2019-02-27 17:40   ` Martin Schwidefsky
2019-02-28 11:43     ` Steven Price
2019-02-27 17:05 ` [PATCH v3 19/34] sh: " Steven Price
2019-02-27 17:05 ` [PATCH v3 20/34] sparc: " Steven Price
2019-02-27 18:38   ` David Miller
2019-02-28 11:49     ` Steven Price
2019-02-27 17:05 ` [PATCH v3 21/34] um: " Steven Price
2019-02-27 17:05 ` [PATCH v3 22/34] unicore32: " Steven Price
2019-02-27 17:05 ` [PATCH v3 23/34] xtensa: " Steven Price
2019-02-27 17:29   ` Max Filippov
2019-02-27 17:05 ` [PATCH v3 24/34] mm: Add generic p?d_large() macros Steven Price
2019-02-27 17:05 ` [PATCH v3 25/34] mm: pagewalk: Add p4d_entry() and pgd_entry() Steven Price
2019-02-27 17:06 ` [PATCH v3 26/34] mm: pagewalk: Allow walking without vma Steven Price
2019-02-27 17:06 ` [PATCH v3 27/34] mm: pagewalk: Add 'depth' parameter to pte_hole Steven Price
2019-02-27 17:38   ` Dave Hansen
2019-02-28 11:28     ` Steven Price
2019-02-28 19:00       ` Dave Hansen
2019-03-01 11:24         ` Steven Price
2019-02-27 17:06 ` [PATCH v3 28/34] mm: pagewalk: Add test_p?d callbacks Steven Price
2019-02-27 17:06 ` [PATCH v3 29/34] arm64: mm: Convert mm/dump.c to use walk_page_range() Steven Price
2019-02-27 17:06 ` [PATCH v3 30/34] x86/mm: Point to struct seq_file from struct pg_state Steven Price
2019-02-27 17:06 ` [PATCH v3 31/34] x86/mm+efi: Convert ptdump_walk_pgd_level() to take a mm_struct Steven Price
2019-02-27 17:06 ` [PATCH v3 32/34] x86/mm: Convert ptdump_walk_pgd_level_debugfs() to take an mm_struct Steven Price
2019-02-27 17:06 ` [PATCH v3 33/34] x86/mm: Convert ptdump_walk_pgd_level_core() " Steven Price
2019-02-27 17:06 ` [PATCH v3 34/34] x86: mm: Convert dump_pagetables to use walk_page_range Steven Price

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