linux-kernel - Re: Re: [RFC PATCH v4 0/6] arm64: tlb: add support for TTL feature

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Message-ID: <fb06ba92-a3ce-6925-e914-167a85837f27@huawei.com>
Date:   Wed, 25 Mar 2020 12:49:45 +0800
From:   Zhenyu Ye <yezhenyu2@...wei.com>
To:     Peter Zijlstra <peterz@...radead.org>
CC:     <mark.rutland@....com>, <catalin.marinas@....com>,
        <linux-mm@...ck.org>, <guohanjun@...wei.com>, <will@...nel.org>,
        <linux-arch@...r.kernel.org>, <yuzhao@...gle.com>,
        <maz@...nel.org>, <steven.price@....com>, <arm@...nel.org>,
        <Dave.Martin@....com>, <arnd@...db.de>, <suzuki.poulose@....com>,
        <npiggin@...il.com>, <zhangshaokun@...ilicon.com>,
        <broonie@...nel.org>, <rostedt@...dmis.org>,
        <prime.zeng@...ilicon.com>, <tglx@...utronix.de>,
        <linux-arm-kernel@...ts.infradead.org>, <xiexiangyou@...wei.com>,
        <linux-kernel@...r.kernel.org>, <aneesh.kumar@...ux.ibm.com>,
        <akpm@...ux-foundation.org>
Subject: Re: Re: [RFC PATCH v4 0/6] arm64: tlb: add support for TTL feature

Hi Peter,

On 2020/3/24 23:01, Peter Zijlstra wrote:
> On Tue, Mar 24, 2020 at 09:45:28PM +0800, Zhenyu Ye wrote:
>> In order to reduce the cost of TLB invalidation, the ARMv8.4 TTL
>> feature allows TLBs to be issued with a level allowing for quicker
>> invalidation.  This series provide support for this feature. 
>>
>> Patch 1 and Patch 2 was provided by Marc on his NV series[1] patches,
>> which detect the TTL feature and add __tlbi_level interface.
> 
> I realy hate how it makes vma->vm_flags more important for tlbi.
> 

Thanks for your review.

The tlbi interfaces only have two parameters: vma and addr. If we
try to not use vma->vm_flags, we may should have to add a parameter
to some of these interfaces(such as flush_tlb_range), which are
common to all architectures.

I'm not sure if this is feasible, because this feature is only
supported by ARM64 currently.


Thanks,
Zhenyu