linux-kernel - Re: [RFC PATCH v4 2/2] arm64: tlb: Use the TLBI RANGE feature in arm64

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Message-ID: <f362680d-b16f-e713-153d-2e026fa8bfd4@huawei.com>
Date:   Wed, 8 Jul 2020 17:01:08 +0800
From:   Zhenyu Ye <yezhenyu2@...wei.com>
To:     Catalin Marinas <catalin.marinas@....com>
CC:     <will@...nel.org>, <suzuki.poulose@....com>, <maz@...nel.org>,
        <steven.price@....com>, <guohanjun@...wei.com>, <olof@...om.net>,
        <linux-arm-kernel@...ts.infradead.org>,
        <linux-kernel@...r.kernel.org>, <linux-arch@...r.kernel.org>,
        <linux-mm@...ck.org>, <arm@...nel.org>, <xiexiangyou@...wei.com>,
        <prime.zeng@...ilicon.com>, <zhangshaokun@...ilicon.com>,
        <kuhn.chenqun@...wei.com>
Subject: Re: [RFC PATCH v4 2/2] arm64: tlb: Use the TLBI RANGE feature in
 arm64

Hi Catalin,

On 2020/7/8 1:36, Catalin Marinas wrote:
> On Mon, Jun 01, 2020 at 10:47:13PM +0800, Zhenyu Ye wrote:
>> @@ -59,6 +69,47 @@
>>  		__ta;						\
>>  	})
>>  
>> +/*
>> + * __TG defines translation granule of the system, which is decided by
>> + * PAGE_SHIFT.  Used by TTL.
>> + *  - 4KB	: 1
>> + *  - 16KB	: 2
>> + *  - 64KB	: 3
>> + */
>> +#define __TG	((PAGE_SHIFT - 12) / 2 + 1)
> 
> Nitpick: maybe something like __TLBI_TG to avoid clashes in case someone
> else defines a __TG macro.
> 

Thanks for your review. According to Marc and Robin's suggestion, I will remove this
macro.
I'd like implement this in a function beacause it's used in both TTL and TLB RANGE.

>> -	for (addr = start; addr < end; addr += stride) {
>> -		if (last_level) {
>> -			__tlbi(vale1is, addr);
>> -			__tlbi_user(vale1is, addr);
>> -		} else {
>> -			__tlbi(vae1is, addr);
>> -			__tlbi_user(vae1is, addr);
>> +	while (range_pages > 0) {
>> +		if (cpus_have_const_cap(ARM64_HAS_TLBI_RANGE) &&
>> +		    stride == PAGE_SIZE) {
> 
> I think we could have the odd range_pages check here:
> 
> 		if (cpus_have_const_cap(ARM64_HAS_TLBI_RANGE) &&
> 		    stride == PAGE_SIZE && range_pages % 2 == 0) {
> 
> and avoid the one outside the loop.
> 

This may need some other necessary changes to do this. See in next version series.

Thanks,
Zhenyu