From: Ryan Roberts <ryan.roberts@arm.com>
To: David Hildenbrand <david@redhat.com>,
Catalin Marinas <catalin.marinas@arm.com>,
Will Deacon <will@kernel.org>, Ard Biesheuvel <ardb@kernel.org>,
Marc Zyngier <maz@kernel.org>, James Morse <james.morse@arm.com>,
Andrey Ryabinin <ryabinin.a.a@gmail.com>,
Andrew Morton <akpm@linux-foundation.org>,
Matthew Wilcox <willy@infradead.org>,
Mark Rutland <mark.rutland@arm.com>,
Kefeng Wang <wangkefeng.wang@huawei.com>,
John Hubbard <jhubbard@nvidia.com>, Zi Yan <ziy@nvidia.com>,
Barry Song <21cnbao@gmail.com>,
Alistair Popple <apopple@nvidia.com>,
Yang Shi <shy828301@gmail.com>,
Nicholas Piggin <npiggin@gmail.com>,
Christophe Leroy <christophe.leroy@csgroup.eu>,
"Aneesh Kumar K.V" <aneesh.kumar@kernel.org>,
"Naveen N. Rao" <naveen.n.rao@linux.ibm.com>,
Thomas Gleixner <tglx@linutronix.de>,
Ingo Molnar <mingo@redhat.com>, Borislav Petkov <bp@alien8.de>,
Dave Hansen <dave.hansen@linux.intel.com>,
"H. Peter Anvin" <hpa@zytor.com>
Cc: linux-arm-kernel@lists.infradead.org, x86@kernel.org,
linuxppc-dev@lists.ozlabs.org, linux-mm@kvack.org,
linux-kernel@vger.kernel.org
Subject: Re: [PATCH v5 03/25] mm: Make pte_next_pfn() a wrapper around pte_advance_pfn()
Date: Mon, 12 Feb 2024 14:10:55 +0000 [thread overview]
Message-ID: <cdf4e537-5b0d-45ba-8094-527127c791a6@arm.com> (raw)
In-Reply-To: <c269c2e0-afca-4ff0-8ffd-9049fb52c905@redhat.com>
On 12/02/2024 12:14, David Hildenbrand wrote:
> On 02.02.24 09:07, Ryan Roberts wrote:
>> The goal is to be able to advance a PTE by an arbitrary number of PFNs.
>> So introduce a new API that takes a nr param.
>>
>> We are going to remove pte_next_pfn() and replace it with
>> pte_advance_pfn(). As a first step, implement pte_next_pfn() as a
>> wrapper around pte_advance_pfn() so that we can incrementally switch the
>> architectures over. Once all arches are moved over, we will change all
>> the core-mm callers to call pte_advance_pfn() directly and remove the
>> wrapper.
>>
>> Signed-off-by: Ryan Roberts <ryan.roberts@arm.com>
>> ---
>> include/linux/pgtable.h | 8 +++++++-
>> 1 file changed, 7 insertions(+), 1 deletion(-)
>>
>> diff --git a/include/linux/pgtable.h b/include/linux/pgtable.h
>> index 5e7eaf8f2b97..815d92dcb96b 100644
>> --- a/include/linux/pgtable.h
>> +++ b/include/linux/pgtable.h
>> @@ -214,9 +214,15 @@ static inline int pmd_dirty(pmd_t pmd)
>> #ifndef pte_next_pfn
>> +#ifndef pte_advance_pfn
>> +static inline pte_t pte_advance_pfn(pte_t pte, unsigned long nr)
>> +{
>> + return __pte(pte_val(pte) + (nr << PFN_PTE_SHIFT));
>> +}
>> +#endif
>> static inline pte_t pte_next_pfn(pte_t pte)
>> {
>> - return __pte(pte_val(pte) + (1UL << PFN_PTE_SHIFT));
>> + return pte_advance_pfn(pte, 1);
>> }
>> #endif
>>
>
> I do wonder if we simply want to leave pte_next_pfn() around? Especially patch
> #4, #6 don't really benefit from the change? So are the other set_ptes()
> implementations.
>
> That is, only convert all pte_next_pfn()->pte_advance_pfn(), and leave a
> pte_next_pfn() macro in place.
>
> Any downsides to that?
The downside is just having multiple functions that effectively do the same
thing. Personally I think its cleaner and easier to understand the code with
just one generic function which we pass 1 to it where we only want to advance by
1. In the end, there are only a couple of places where pte_advance_pfn(1) is
used, so doesn't really seem valuable to me to maintain a specialization.
Unless you feel strongly that we need to keep pte_next_pfn() then I'd prefer to
leave it as I've done in this series.
> This patch here would become:
>
> #ifndef pte_advance_pfn
> static inline pte_t pte_advance_pfn(pte_t pte, unsigned long nr)
> {
> return __pte(pte_val(pte) + (nr << PFN_PTE_SHIFT));
> }
> #endif
>
> #ifndef pte_next_pfn
> #define pte_next_pfn(pte) pte_advance_pfn(pte, 1)
> #endif
>
> As you convert the three arches, make them define pte_advance_pfn and udnefine
> pte_next_pfn. in the end, you can drop the #ifdef around pte_next_pfn here.
>
next prev parent reply other threads:[~2024-02-12 14:11 UTC|newest]
Thread overview: 80+ messages / expand[flat|nested] mbox.gz Atom feed top
2024-02-02 8:07 [PATCH v5 00/25] Transparent Contiguous PTEs for User Mappings Ryan Roberts
2024-02-02 8:07 ` [PATCH v5 01/25] mm: Clarify the spec for set_ptes() Ryan Roberts
2024-02-12 12:03 ` David Hildenbrand
2024-02-02 8:07 ` [PATCH v5 02/25] mm: thp: Batch-collapse PMD with set_ptes() Ryan Roberts
2024-02-02 8:07 ` [PATCH v5 03/25] mm: Make pte_next_pfn() a wrapper around pte_advance_pfn() Ryan Roberts
2024-02-12 12:14 ` David Hildenbrand
2024-02-12 14:10 ` Ryan Roberts [this message]
2024-02-12 14:29 ` David Hildenbrand
2024-02-12 21:34 ` Ryan Roberts
2024-02-13 9:54 ` David Hildenbrand
2024-02-02 8:07 ` [PATCH v5 04/25] arm/mm: Convert pte_next_pfn() to pte_advance_pfn() Ryan Roberts
2024-02-02 8:07 ` [PATCH v5 05/25] arm64/mm: " Ryan Roberts
2024-02-02 8:07 ` [PATCH v5 06/25] powerpc/mm: " Ryan Roberts
2024-02-02 8:07 ` [PATCH v5 07/25] x86/mm: " Ryan Roberts
2024-02-02 8:07 ` [PATCH v5 08/25] mm: Remove pte_next_pfn() and replace with pte_advance_pfn() Ryan Roberts
2024-02-02 8:07 ` [PATCH v5 09/25] arm64/mm: set_pte(): New layer to manage contig bit Ryan Roberts
2024-02-02 8:07 ` [PATCH v5 10/25] arm64/mm: set_ptes()/set_pte_at(): " Ryan Roberts
2024-02-02 8:07 ` [PATCH v5 11/25] arm64/mm: pte_clear(): " Ryan Roberts
2024-02-02 8:07 ` [PATCH v5 12/25] arm64/mm: ptep_get_and_clear(): " Ryan Roberts
2024-02-02 8:07 ` [PATCH v5 13/25] arm64/mm: ptep_test_and_clear_young(): " Ryan Roberts
2024-02-02 8:07 ` [PATCH v5 14/25] arm64/mm: ptep_clear_flush_young(): " Ryan Roberts
2024-02-02 8:07 ` [PATCH v5 15/25] arm64/mm: ptep_set_wrprotect(): " Ryan Roberts
2024-02-02 8:07 ` [PATCH v5 16/25] arm64/mm: ptep_set_access_flags(): " Ryan Roberts
2024-02-02 8:07 ` [PATCH v5 17/25] arm64/mm: ptep_get(): " Ryan Roberts
2024-02-02 8:07 ` [PATCH v5 18/25] arm64/mm: Split __flush_tlb_range() to elide trailing DSB Ryan Roberts
2024-02-12 12:44 ` David Hildenbrand
2024-02-12 13:05 ` Ryan Roberts
2024-02-12 13:15 ` David Hildenbrand
2024-02-12 13:27 ` Ryan Roberts
2024-02-02 8:07 ` [PATCH v5 19/25] arm64/mm: Wire up PTE_CONT for user mappings Ryan Roberts
2024-02-12 12:00 ` Mark Rutland
2024-02-12 12:59 ` Ryan Roberts
2024-02-12 13:54 ` David Hildenbrand
2024-02-12 14:45 ` Ryan Roberts
2024-02-12 15:26 ` David Hildenbrand
2024-02-12 15:34 ` Ryan Roberts
2024-02-12 16:24 ` David Hildenbrand
2024-02-13 15:29 ` Ryan Roberts
2024-02-12 15:30 ` Ryan Roberts
2024-02-12 20:38 ` Ryan Roberts
2024-02-13 10:01 ` David Hildenbrand
2024-02-13 12:06 ` Ryan Roberts
2024-02-13 12:19 ` David Hildenbrand
2024-02-13 13:06 ` Ryan Roberts
2024-02-13 13:13 ` David Hildenbrand
2024-02-13 13:20 ` Ryan Roberts
2024-02-13 13:22 ` David Hildenbrand
2024-02-13 13:24 ` Ryan Roberts
2024-02-13 13:33 ` Ard Biesheuvel
2024-02-13 13:45 ` David Hildenbrand
2024-02-13 14:02 ` Ryan Roberts
2024-02-13 14:05 ` David Hildenbrand
2024-02-13 14:08 ` Ard Biesheuvel
2024-02-13 14:21 ` Ryan Roberts
2024-02-13 12:02 ` Mark Rutland
2024-02-13 13:03 ` Ryan Roberts
2024-02-02 8:07 ` [PATCH v5 20/25] arm64/mm: Implement new wrprotect_ptes() batch API Ryan Roberts
2024-02-13 16:31 ` Mark Rutland
2024-02-13 16:36 ` Ryan Roberts
2024-02-02 8:07 ` [PATCH v5 21/25] arm64/mm: Implement new [get_and_]clear_full_ptes() batch APIs Ryan Roberts
2024-02-13 16:43 ` Mark Rutland
2024-02-13 16:48 ` Ryan Roberts
2024-02-13 16:53 ` Mark Rutland
2024-02-02 8:07 ` [PATCH v5 22/25] mm: Add pte_batch_hint() to reduce scanning in folio_pte_batch() Ryan Roberts
2024-02-12 13:43 ` David Hildenbrand
2024-02-12 15:00 ` Ryan Roberts
2024-02-12 15:47 ` Ryan Roberts
2024-02-12 16:27 ` David Hildenbrand
2024-02-02 8:07 ` [PATCH v5 23/25] arm64/mm: Implement pte_batch_hint() Ryan Roberts
2024-02-12 13:46 ` David Hildenbrand
2024-02-13 16:54 ` Mark Rutland
2024-02-02 8:07 ` [PATCH v5 24/25] arm64/mm: __always_inline to improve fork() perf Ryan Roberts
2024-02-13 16:55 ` Mark Rutland
2024-02-02 8:07 ` [PATCH v5 25/25] arm64/mm: Automatically fold contpte mappings Ryan Roberts
2024-02-13 17:44 ` Mark Rutland
2024-02-13 18:05 ` Ryan Roberts
2024-02-08 17:34 ` [PATCH v5 00/25] Transparent Contiguous PTEs for User Mappings Mark Rutland
2024-02-09 8:54 ` Ryan Roberts
2024-02-09 22:16 ` David Hildenbrand
2024-02-09 23:52 ` Ryan Roberts
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