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=-12.3 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH, MAILING_LIST_MULTI,NICE_REPLY_A,SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_1 autolearn=ham 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 E285DC47089 for ; Thu, 27 May 2021 13:30:26 +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 A8B196128B for ; Thu, 27 May 2021 13:30:26 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org A8B196128B 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.133420.248710 (Exim 4.92) (envelope-from ) id 1lmG5U-0002zX-Ew; Thu, 27 May 2021 13:30:12 +0000 X-Outflank-Mailman: Message body and most headers restored to incoming version Received: by outflank-mailman (output) from mailman id 133420.248710; Thu, 27 May 2021 13:30:12 +0000 Received: from localhost ([127.0.0.1] helo=lists.xenproject.org) by lists.xenproject.org with esmtp (Exim 4.92) (envelope-from ) id 1lmG5U-0002zQ-Bd; Thu, 27 May 2021 13:30:12 +0000 Received: by outflank-mailman (input) for mailman id 133420; Thu, 27 May 2021 13:30:11 +0000 Received: from mail.xenproject.org ([104.130.215.37]) by lists.xenproject.org with esmtp (Exim 4.92) (envelope-from ) id 1lmG5S-0002zI-Ur for xen-devel@lists.xenproject.org; Thu, 27 May 2021 13:30:10 +0000 Received: from xenbits.xenproject.org ([104.239.192.120]) by mail.xenproject.org with esmtp (Exim 4.92) (envelope-from ) id 1lmG5S-0000FM-R9; Thu, 27 May 2021 13:30:10 +0000 Received: from [54.239.6.188] (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 1lmG5S-0002vw-KM; Thu, 27 May 2021 13:30:10 +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=EX10sFiK/vacdc2TZCENeLUkaSzkI9mwdbhchUhK9h4=; b=40ClmA2MdSyXfB/92gxtvklrho M90uTXRiUnqgGhT8zSV+CLp0+UDlJ7rcx0EDCBqkshtwb6eYuhdiws/WgvsGiLFcKkqua0HDwl80N qpOdIGdS9bU++hKkjuD1hEtkzVntcnwpr95pwgm7rIOF5FuQlfvD1380KW3cvInkpwwU=; Subject: Re: [PATCH v2 01/12] x86: introduce ioremap_wc() To: Jan Beulich Cc: Andrew Cooper , Wei Liu , =?UTF-8?Q?Roger_Pau_Monn=c3=a9?= , "xen-devel@lists.xenproject.org" References: <8f56a8f4-0482-932f-96a9-c791bebb4610@suse.com> <20abac99-609c-f4f6-1242-c79919f4c317@suse.com> From: Julien Grall Message-ID: <7d32ff1c-315c-f2da-bc1b-06fb2233fe55@xen.org> Date: Thu, 27 May 2021 14:30:08 +0100 User-Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.15; rv:78.0) Gecko/20100101 Thunderbird/78.10.2 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 Jan, On 27/05/2021 14:09, Jan Beulich wrote: > On 27.05.2021 14:48, Julien Grall wrote: >> On 27/05/2021 13:30, Jan Beulich wrote: >>> --- a/xen/arch/x86/mm.c >>> +++ b/xen/arch/x86/mm.c >>> @@ -5881,6 +5881,20 @@ void __iomem *ioremap(paddr_t pa, size_t >>> return (void __force __iomem *)va; >>> } >>> >>> +void __iomem *__init ioremap_wc(paddr_t pa, size_t len) >>> +{ >>> + mfn_t mfn = _mfn(PFN_DOWN(pa)); >>> + unsigned int offs = pa & (PAGE_SIZE - 1); >>> + unsigned int nr = PFN_UP(offs + len); >>> + void *va; >>> + >>> + WARN_ON(page_is_ram_type(mfn_x(mfn), RAM_TYPE_CONVENTIONAL)); >>> + >>> + va = __vmap(&mfn, nr, 1, 1, PAGE_HYPERVISOR_WC, VMAP_DEFAULT); >>> + >>> + return (void __force __iomem *)(va + offs); >>> +} >> >> Arm is already providing ioremap_wc() which is a wrapper to >> ioremap_attr(). > > I did notice this, yes. > >> Can this be moved to the common code to avoid duplication? > > If by "this" you mean ioremap_attr(), then I wasn't convinced we want > a function of this name on x86. I am open to other name. > In particular you may note that > x86'es ioremap() is sort of the equivalent of Arm's ioremap_nocache(), > but is different from the new ioremap_wc() by more than just the > different PTE attributes. That's because ioremap() will not vmap() the first MB, am I correct? If so, I am not sure why you want to do that in ioremap() but not ioremap_wc(). Wouldn't this result access the memory with mismatched attributes? > Also I was specifically asked to make ioremap_wc() __init; ioremap() > cannot be, because of at least the use from pci_vtd_quirk(). I am not sure this is relevant to the conversation here. I am sure there are other function that would benefits to be __init in one arch but can't in the other. Yet, common code can be beneficials. > > Plus I'd need to clean up Arm's lack of __iomem if I wanted to fold > things. __iomem is NOP on Xen. So while the annotation may not be consistently used, I don't see the clean-up a requirement to consolidate the code... > Or wait - it's declaration and definition which are out of > sync there, i.e. a pre-existing issue. We don't usually add __init on both the declaration and definition. So why would it be necessary to add __iomem in both cases? Cheers, -- Julien Grall