From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-7.3 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI, NICE_REPLY_A,SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_1 autolearn=no autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 967B2C07E97 for ; Sat, 3 Jul 2021 17:33:02 +0000 (UTC) Received: from lists.xenproject.org (lists.xenproject.org [192.237.175.120]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id 4E413613CD for ; Sat, 3 Jul 2021 17:33:02 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 4E413613CD Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=xen.org Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=xen-devel-bounces@lists.xenproject.org Received: from list by lists.xenproject.org with outflank-mailman.149581.276673 (Exim 4.92) (envelope-from ) id 1lzjVY-00066n-5k; Sat, 03 Jul 2021 17:32:48 +0000 X-Outflank-Mailman: Message body and most headers restored to incoming version Received: by outflank-mailman (output) from mailman id 149581.276673; Sat, 03 Jul 2021 17:32:48 +0000 Received: from localhost ([127.0.0.1] helo=lists.xenproject.org) by lists.xenproject.org with esmtp (Exim 4.92) (envelope-from ) id 1lzjVY-00066g-2j; Sat, 03 Jul 2021 17:32:48 +0000 Received: by outflank-mailman (input) for mailman id 149581; Sat, 03 Jul 2021 17:32:47 +0000 Received: from mail.xenproject.org ([104.130.215.37]) by lists.xenproject.org with esmtp (Exim 4.92) (envelope-from ) id 1lzjVX-00066a-CU for xen-devel@lists.xenproject.org; Sat, 03 Jul 2021 17:32:47 +0000 Received: from xenbits.xenproject.org ([104.239.192.120]) by mail.xenproject.org with esmtp (Exim 4.92) (envelope-from ) id 1lzjVV-00084K-K9; Sat, 03 Jul 2021 17:32:45 +0000 Received: from [54.239.6.185] (helo=a483e7b01a66.ant.amazon.com) by xenbits.xenproject.org with esmtpsa (TLS1.3:ECDHE_RSA_AES_128_GCM_SHA256:128) (Exim 4.92) (envelope-from ) id 1lzjVV-0007Gb-Dx; Sat, 03 Jul 2021 17:32:45 +0000 X-BeenThere: xen-devel@lists.xenproject.org List-Id: Xen developer discussion List-Unsubscribe: , List-Post: List-Help: List-Subscribe: , Errors-To: xen-devel-bounces@lists.xenproject.org Precedence: list Sender: "Xen-devel" DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=xen.org; s=20200302mail; h=Content-Transfer-Encoding:Content-Type:In-Reply-To: MIME-Version:Date:Message-ID:From:References:Cc:To:Subject; bh=3Tza1UvXeufzHbNeU33KlJq7y0V7wQ/yltCLXkHqNMw=; b=zjHKeanavASjFJ6MALVKr2cEwn rXrcD9cn6UiDzTNkCQgBksG8jpDVAtcUV62yxOCOz3HjreoFf80Yo58Tx+9s5Bk9zmLlp65gZULuh hjbgHLcv0h4ZzW2GdFV07KjqtlpE7Bd9fk6anKajX/WYSc+9ECx2DC/1QdBLQmE/GzBE=; Subject: Re: [PATCH RFCv2 02/15] xen/arm: lpae: Use the generic helpers to defined the Xen PT helpers To: Stefano Stabellini Cc: xen-devel@lists.xenproject.org, Wei.Chen@arm.com, Henry.Wang@arm.com, Penny.Zheng@arm.com, Bertrand.Marquis@arm.com, Julien Grall , Volodymyr Babchuk References: <20210425201318.15447-1-julien@xen.org> <20210425201318.15447-3-julien@xen.org> <94e364a7-de40-93ab-6cde-a2f493540439@xen.org> From: Julien Grall Message-ID: <9397d94d-5a22-c026-7c66-400b7397c2fa@xen.org> Date: Sat, 3 Jul 2021 18:32:43 +0100 User-Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.15; rv:78.0) Gecko/20100101 Thunderbird/78.11.0 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-GB Content-Transfer-Encoding: 7bit Hi Stefano, Sorry for the late answer. On 13/05/2021 23:44, Stefano Stabellini wrote: > On Wed, 12 May 2021, Julien Grall wrote: >> Hi Stefano, >> >> On 12/05/2021 22:30, Stefano Stabellini wrote: >>> On Wed, 12 May 2021, Julien Grall wrote: >>>>>> +#define LPAE_SHIFT LPAE_SHIFT_GS(PAGE_SHIFT) >>>>>> +#define LPAE_ENTRIES LPAE_ENTRIES_GS(PAGE_SHIFT) >>>>>> +#define LPAE_ENTRY_MASK LPAE_ENTRY_MASK_GS(PAGE_SHIFT) >>>>>> >>>>>> +#define LEVEL_SHIFT(lvl) LEVEL_SHIFT_GS(PAGE_SHIFT, lvl) >>>>>> +#define LEVEL_ORDER(lvl) LEVEL_ORDER_GS(PAGE_SHIFT, lvl) >>>>>> +#define LEVEL_SIZE(lvl) LEVEL_SIZE_GS(PAGE_SHIFT, lvl) >>>>>> +#define LEVEL_MASK(lvl) (~(LEVEL_SIZE(lvl) - 1)) >>>>> >>>>> I would avoid adding these 4 macros. It would be OK if they were just >>>>> used within this file but lpae.h is a header: they could end up be used >>>>> anywhere in the xen/ code and they have a very generic name. My >>>>> suggestion would be to skip them and just do: >>>> >>>> Those macros will be used in follow-up patches. They are pretty useful to >>>> avoid introduce static array with the different information for each >>>> level. >>>> >>>> Would prefix them with XEN_ be better? >>> >>> Maybe. The concern I have is that there are multiple page granularities >>> (4kb, 16kb, etc) and multiple page sizes (4kb, 2mb, etc). If I just see >>> LEVEL_ORDER it is not immediately obvious what granularity and what size >>> we are talking about. >> >> I am a bit puzzled with your answer. AFAIU, you are happy with the existing >> macros (THIRD_*, SECOND_*) but not with the new macros. >> >> In reality, there is no difference because THIRD_* doesn't tell you the exact >> size but only "this is a level 3 mapping". >> >> So can you clarify what you are after? IOW is it reworking the current naming >> scheme? > > You are right -- there is no real difference between THIRD_*, SECOND_* > and LEVEL_*. > > The original reason for my comments is that I hadn't read the following > patches, and the definition of LEVEL_* macros is simple, they could be > open coded. It looked like they were only going to be used to make the > definition of THIRD_*, SECOND_* a bit easier. So, at first, I was > wondering if they were needed at all. > > Secondly, I realized that they were going to be used in *.c files by > other patches. That's why they are there. But I started thinking whether > we should find a way to make it a bit clearer that they are for Xen > pages, currently at 4KB granularity. THIRD_*, SECOND_*, etc. are already > generic names which don't convey the granularity or whether they are Xen > pages at all. But LEVEL_* seem even more generic. > > As I mentioned, I don't have any good suggestions for changes to make > here, so unless you can come up with a good idea let's keep it as is. I am thinking to use the following naming (diff on top of this patch): -#define LPAE_SHIFT LPAE_SHIFT_GS(PAGE_SHIFT) -#define LPAE_ENTRIES LPAE_ENTRIES_GS(PAGE_SHIFT) -#define LPAE_ENTRY_MASK LPAE_ENTRY_MASK_GS(PAGE_SHIFT) +#define XEN_PT_SHIFT LPAE_SHIFT_GS(PAGE_SHIFT) +#define XEN_PT_ENTRIES LPAE_ENTRIES_GS(PAGE_SHIFT) +#define XEN_PT_ENTRY_MASK LPAE_ENTRY_MASK_GS(PAGE_SHIFT) -#define LEVEL_SHIFT(lvl) LEVEL_SHIFT_GS(PAGE_SHIFT, lvl) -#define LEVEL_ORDER(lvl) LEVEL_ORDER_GS(PAGE_SHIFT, lvl) -#define LEVEL_SIZE(lvl) LEVEL_SIZE_GS(PAGE_SHIFT, lvl) -#define LEVEL_MASK(lvl) (~(LEVEL_SIZE(lvl) - 1)) +#define XEN_PT_LEVEL_SHIFT(lvl) LEVEL_SHIFT_GS(PAGE_SHIFT, lvl) +#define XEN_PT_LEVEL_ORDER(lvl) LEVEL_ORDER_GS(PAGE_SHIFT, lvl) +#define XEN_PT_LEVEL_SIZE(lvl) LEVEL_SIZE_GS(PAGE_SHIFT, lvl) +#define XEN_PT_LEVEL_MASK(lvl) (~(LEVEL_SIZE(lvl) - 1)) /* Convenience aliases */ -#define THIRD_SHIFT LEVEL_SHIFT(3) -#define THIRD_ORDER LEVEL_ORDER(3) -#define THIRD_SIZE LEVEL_SIZE(3) -#define THIRD_MASK LEVEL_MASK(3) - -#define SECOND_SHIFT LEVEL_SHIFT(2) -#define SECOND_ORDER LEVEL_ORDER(2) -#define SECOND_SIZE LEVEL_SIZE(2) -#define SECOND_MASK LEVEL_MASK(2) - -#define FIRST_SHIFT LEVEL_SHIFT(1) -#define FIRST_ORDER LEVEL_ORDER(1) -#define FIRST_SIZE LEVEL_SIZE(1) -#define FIRST_MASK LEVEL_MASK(1) - -#define ZEROETH_SHIFT LEVEL_SHIFT(0) -#define ZEROETH_ORDER LEVEL_ORDER(0) -#define ZEROETH_SIZE LEVEL_SIZE(0) -#define ZEROETH_MASK LEVEL_MASK(0) +#define THIRD_SHIFT XEN_PT_LEVEL_SHIFT(3) +#define THIRD_ORDER XEN_PT_LEVEL_ORDER(3) +#define THIRD_SIZE XEN_PT_LEVEL_SIZE(3) +#define THIRD_MASK XEN_PT_LEVEL_MASK(3) + +#define SECOND_SHIFT XEN_PT_LEVEL_SHIFT(2) +#define SECOND_ORDER XEN_PT_LEVEL_ORDER(2) +#define SECOND_SIZE XEN_PT_LEVEL_SIZE(2) +#define SECOND_MASK XEN_PT_LEVEL_MASK(2) + +#define FIRST_SHIFT XEN_PT_LEVEL_SHIFT(1) +#define FIRST_ORDER XEN_PT_LEVEL_ORDER(1) +#define FIRST_SIZE XEN_PT_LEVEL_SIZE(1) +#define FIRST_MASK XEN_PT_LEVEL_MASK(1) + +#define ZEROETH_SHIFT XEN_PT_LEVEL_SHIFT(0) +#define ZEROETH_ORDER XEN_PT_LEVEL_ORDER(0) +#define ZEROETH_SIZE XEN_PT_LEVEL_SIZE(0) +#define ZEROETH_MASK XEN_PT_LEVEL_MASK(0) I don't plan to modify the nameing for ZEROETH*, FIRST*, SECOND*, THIRD*. Let me know if you prefer it over the currrent naming. Cheers, -- Julien Grall