From: Zhenyu Ye <yezhenyu2@huawei.com>
To: Catalin Marinas <catalin.marinas@arm.com>
Cc: <peterz@infradead.org>, <mark.rutland@arm.com>, <will@kernel.org>,
<aneesh.kumar@linux.ibm.com>, <akpm@linux-foundation.org>,
<npiggin@gmail.com>, <arnd@arndb.de>, <rostedt@goodmis.org>,
<maz@kernel.org>, <suzuki.poulose@arm.com>, <tglx@linutronix.de>,
<yuzhao@google.com>, <Dave.Martin@arm.com>,
<steven.price@arm.com>, <broonie@kernel.org>,
<guohanjun@huawei.com>, <linux-arm-kernel@lists.infradead.org>,
<linux-kernel@vger.kernel.org>, <linux-arch@vger.kernel.org>,
<linux-mm@kvack.org>, <arm@kernel.org>, <xiexiangyou@huawei.com>,
<prime.zeng@hisilicon.com>, <zhangshaokun@hisilicon.com>,
<kuhn.chenqun@huawei.com>
Subject: Re: [PATCH v2 5/6] mm: tlb: Provide flush_*_tlb_range wrappers
Date: Sat, 30 May 2020 18:24:21 +0800 [thread overview]
Message-ID: <0c6f79e4-f29a-d373-2e43-c4f87cf78b49@huawei.com> (raw)
In-Reply-To: <20200526145244.GG17051@gaia>
Hi Catalin,
Sorry for taking so long to reply to you.
On 2020/5/26 22:52, Catalin Marinas wrote:
> On Mon, May 25, 2020 at 03:19:42PM +0800, Zhenyu Ye wrote:
>>
>> tlb_flush_##_pxx##_range() is used to set tlb->cleared_*,
>> flush_##_pxx##_tlb_range() will actually flush the TLB entry.
>>
>> In arch64, tlb_flush_p?d_range() is defined as:
>>
>> #define flush_pmd_tlb_range(vma, addr, end) flush_tlb_range(vma, addr, end)
>> #define flush_pud_tlb_range(vma, addr, end) flush_tlb_range(vma, addr, end)
>
> Currently, flush_p??_tlb_range() are generic and defined as above. I
> think in the generic code they can remain an alias for
> flush_tlb_range().
>
> On arm64, we can redefine them as:
>
> #define flush_pte_tlb_range(vma, addr, end) __flush_tlb_range(vma, addr, end, 3)
> #define flush_pmd_tlb_range(vma, addr, end) __flush_tlb_range(vma, addr, end, 2)
> #define flush_pud_tlb_range(vma, addr, end) __flush_tlb_range(vma, addr, end, 1)
> #define flush_p4d_tlb_range(vma, addr, end) __flush_tlb_range(vma, addr, end, 0)
>
> (unless the compiler optimises away all the mmu_gather stuff in your
> macro above but they don't look trivial to me)
>
I changed generic code before considering that other structures may also
use this feature, such as Power9. And Peter may want to replace all
flush_tlb_range() by tlb_flush() in the future, see [1] for details.
If only enable this feature on aarch64, your codes are better.
[1] https://lore.kernel.org/linux-arm-kernel/20200402163849.GM20713@hirez.programming.kicks-ass.net/
> Also, I don't see the new flush_pte_* and flush_p4d_* macros used
> anywhere and I don't think they are needed. The pte equivalent is
> flush_tlb_page() (we need to make sure it's not used on a pmd in the
> hugetlb context).
>
flush_tlb_page() is used to flush only one page. If we add the flush_pte_tlb_range(),
then we can use it to flush a range of pages in the future.
But flush_pte_* and flush_p4d_* macros are really not used anywhere.
I will remove them in next version of series, and add them if someone needs.
>> So even if we know the level here, we can not pass the value to tlbi
>> instructions (flush_tlb_range() is a common kernel interface and retro-fit it
>> needs lots of changes), according to Peter's suggestion, I finally decide to
>> pass the value of TTL by the tlb_gather_* frame.[1]
>
> My comment was about the generic implementation using mmu_gather as you
> are proposing. We don't need to change the flush_tlb_range() interface,
> nor do we need to rewrite flush_p??_tlb_range().
>
Thanks,
Zhenyu
next prev parent reply other threads:[~2020-05-30 10:24 UTC|newest]
Thread overview: 21+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-04-23 13:56 [PATCH v2 0/6] arm64: tlb: add support for TTL feature Zhenyu Ye
2020-04-23 13:56 ` [PATCH v2 1/6] arm64: Detect the ARMv8.4 " Zhenyu Ye
2020-05-22 15:50 ` Catalin Marinas
2020-04-23 13:56 ` [PATCH v2 2/6] arm64: Add level-hinted TLB invalidation helper Zhenyu Ye
2020-05-22 15:50 ` Catalin Marinas
2020-05-25 6:54 ` Zhenyu Ye
2020-04-23 13:56 ` [PATCH v2 3/6] arm64: Add tlbi_user_level " Zhenyu Ye
2020-05-22 15:49 ` Catalin Marinas
2020-05-25 6:57 ` Zhenyu Ye
2020-04-23 13:56 ` [PATCH v2 4/6] tlb: mmu_gather: add tlb_flush_*_range APIs Zhenyu Ye
2020-05-22 15:50 ` Catalin Marinas
2020-04-23 13:56 ` [PATCH v2 5/6] mm: tlb: Provide flush_*_tlb_range wrappers Zhenyu Ye
2020-05-22 15:42 ` Catalin Marinas
2020-05-25 7:19 ` Zhenyu Ye
2020-05-26 14:52 ` Catalin Marinas
2020-05-30 10:24 ` Zhenyu Ye [this message]
2020-06-01 11:56 ` Catalin Marinas
2020-06-01 13:36 ` Zhenyu Ye
2020-04-23 13:56 ` [PATCH v2 6/6] arm64: tlb: Set the TTL field in flush_tlb_range Zhenyu Ye
2020-05-26 14:56 ` Catalin Marinas
2020-05-11 12:41 ` [PATCH v2 0/6] arm64: tlb: add support for TTL feature Zhenyu Ye
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