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=-10.3 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,MAILING_LIST_MULTI, NICE_REPLY_A,SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_1 autolearn=unavailable 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 42BD9C433DB for ; Thu, 18 Mar 2021 19:54:53 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 1337264F04 for ; Thu, 18 Mar 2021 19:54:53 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S232786AbhCRTyX (ORCPT ); Thu, 18 Mar 2021 15:54:23 -0400 Received: from foss.arm.com ([217.140.110.172]:47794 "EHLO foss.arm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230008AbhCRTxr (ORCPT ); Thu, 18 Mar 2021 15:53:47 -0400 Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.121.207.14]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id A8D4031B; Thu, 18 Mar 2021 12:53:46 -0700 (PDT) Received: from [10.57.50.37] (unknown [10.57.50.37]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 005C33F792; Thu, 18 Mar 2021 12:53:43 -0700 (PDT) Subject: Re: [PATCH] swiotlb: Add swiotlb=off to disable SWIOTLB To: Florian Fainelli , linux-kernel@vger.kernel.org, Christoph Hellwig Cc: Jonathan Corbet , opendmb@gmail.com, "Paul E. McKenney" , Konrad Rzeszutek Wilk , Mauro Carvalho Chehab , Viresh Kumar , Randy Dunlap , "open list:DOCUMENTATION" , Peter Zijlstra , "open list:SWIOTLB SUBSYSTEM" , Andrew Morton , Mike Kravetz , Thomas Gleixner References: <20210318191816.4185226-1-f.fainelli@gmail.com> From: Robin Murphy Message-ID: <16d1c66f-5451-2515-af73-a6b44d996e92@arm.com> Date: Thu, 18 Mar 2021 19:53:37 +0000 User-Agent: Mozilla/5.0 (Windows NT 10.0; rv:78.0) Gecko/20100101 Thunderbird/78.8.1 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-GB Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 2021-03-18 19:43, Florian Fainelli wrote: > > > On 3/18/2021 12:34 PM, Robin Murphy wrote: >> On 2021-03-18 19:22, Florian Fainelli wrote: >>> >>> >>> On 3/18/2021 12:18 PM, Florian Fainelli wrote: >>>> It may be useful to disable the SWIOTLB completely for testing or when a >>>> platform is known not to have any DRAM addressing limitations what so >>>> ever. >> >> Isn't that what "swiotlb=noforce" is for? If you're confident that we've >> really ironed out *all* the awkward corners that used to blow up if >> various internal bits were left uninitialised, then it would make sense >> to just tweak the implementation of what we already have. > > swiotlb=noforce does prevent dma_direct_map_page() from resorting to the > swiotlb, however what I am also after is reclaiming these 64MB of > default SWIOTLB bounce buffering memory because my systems run with > large amounts of reserved memory into ZONE_MOVABLE and everything in > ZONE_NORMAL is precious at that point. It also forces io_tlb_nslabs to the minimum, so it should be claiming considerably less than 64MB. IIRC the original proposal *did* skip initialisation completely, but that turned up the aforementioned issues. >> I wouldn't necessarily disagree with adding "off" as an additional alias >> for "noforce", though, since it does come across as a bit wacky for >> general use. >> >>>> Signed-off-by: Florian Fainelli >>> >>> Christoph, in addition to this change, how would you feel if we >>> qualified the swiotlb_init() in arch/arm/mm/init.c with a: >>> >>> >>> if (memblock_end_of_DRAM() >= SZ_4G) >>>     swiotlb_init(1) >> >> Modulo "swiotlb=force", of course ;) > > Indeed, we would need to handle that case as well. Does it sound > reasonable to do that to you as well? I wouldn't like it done to me personally, but for arm64, observe what mem_init() in arch/arm64/mm/init.c already does. Robin. 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=-10.3 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,MAILING_LIST_MULTI, NICE_REPLY_A,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,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 367BAC433DB for ; Thu, 18 Mar 2021 19:53:51 +0000 (UTC) Received: from smtp4.osuosl.org (smtp4.osuosl.org [140.211.166.137]) (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 C1DE764F10 for ; Thu, 18 Mar 2021 19:53:50 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org C1DE764F10 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=arm.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=iommu-bounces@lists.linux-foundation.org Received: from localhost (localhost [127.0.0.1]) by smtp4.osuosl.org (Postfix) with ESMTP id 8B6004E22C; Thu, 18 Mar 2021 19:53:50 +0000 (UTC) X-Virus-Scanned: amavisd-new at osuosl.org Received: from smtp4.osuosl.org ([127.0.0.1]) by localhost (smtp4.osuosl.org [127.0.0.1]) (amavisd-new, port 10024) with ESMTP id nHYuA73G2wk1; Thu, 18 Mar 2021 19:53:49 +0000 (UTC) Received: from lists.linuxfoundation.org (lf-lists.osuosl.org [140.211.9.56]) by smtp4.osuosl.org (Postfix) with ESMTP id 394524DDE7; Thu, 18 Mar 2021 19:53:49 +0000 (UTC) Received: from lf-lists.osuosl.org (localhost [127.0.0.1]) by lists.linuxfoundation.org (Postfix) with ESMTP id 1F39DC000B; Thu, 18 Mar 2021 19:53:49 +0000 (UTC) Received: from smtp1.osuosl.org (smtp1.osuosl.org [IPv6:2605:bc80:3010::138]) by lists.linuxfoundation.org (Postfix) with ESMTP id 58FB4C0001 for ; Thu, 18 Mar 2021 19:53:48 +0000 (UTC) Received: from localhost (localhost [127.0.0.1]) by smtp1.osuosl.org (Postfix) with ESMTP id 54863842C4 for ; Thu, 18 Mar 2021 19:53:48 +0000 (UTC) X-Virus-Scanned: amavisd-new at osuosl.org Received: from smtp1.osuosl.org ([127.0.0.1]) by localhost (smtp1.osuosl.org [127.0.0.1]) (amavisd-new, port 10024) with ESMTP id Ks486EjivL6L for ; Thu, 18 Mar 2021 19:53:47 +0000 (UTC) X-Greylist: domain auto-whitelisted by SQLgrey-1.8.0 Received: from foss.arm.com (foss.arm.com [217.140.110.172]) by smtp1.osuosl.org (Postfix) with ESMTP id 69482842C3 for ; Thu, 18 Mar 2021 19:53:47 +0000 (UTC) Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.121.207.14]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id A8D4031B; Thu, 18 Mar 2021 12:53:46 -0700 (PDT) Received: from [10.57.50.37] (unknown [10.57.50.37]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 005C33F792; Thu, 18 Mar 2021 12:53:43 -0700 (PDT) Subject: Re: [PATCH] swiotlb: Add swiotlb=off to disable SWIOTLB To: Florian Fainelli , linux-kernel@vger.kernel.org, Christoph Hellwig References: <20210318191816.4185226-1-f.fainelli@gmail.com> From: Robin Murphy Message-ID: <16d1c66f-5451-2515-af73-a6b44d996e92@arm.com> Date: Thu, 18 Mar 2021 19:53:37 +0000 User-Agent: Mozilla/5.0 (Windows NT 10.0; rv:78.0) Gecko/20100101 Thunderbird/78.8.1 MIME-Version: 1.0 In-Reply-To: Content-Language: en-GB Cc: opendmb@gmail.com, "Paul E. McKenney" , Konrad Rzeszutek Wilk , Mauro Carvalho Chehab , Viresh Kumar , Jonathan Corbet , "open list:DOCUMENTATION" , Peter Zijlstra , "open list:SWIOTLB SUBSYSTEM" , Randy Dunlap , Andrew Morton , Thomas Gleixner , Mike Kravetz X-BeenThere: iommu@lists.linux-foundation.org X-Mailman-Version: 2.1.15 Precedence: list List-Id: Development issues for Linux IOMMU support List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Transfer-Encoding: base64 Content-Type: text/plain; charset="utf-8"; Format="flowed" Errors-To: iommu-bounces@lists.linux-foundation.org Sender: "iommu" T24gMjAyMS0wMy0xOCAxOTo0MywgRmxvcmlhbiBGYWluZWxsaSB3cm90ZToKPiAKPiAKPiBPbiAz LzE4LzIwMjEgMTI6MzQgUE0sIFJvYmluIE11cnBoeSB3cm90ZToKPj4gT24gMjAyMS0wMy0xOCAx OToyMiwgRmxvcmlhbiBGYWluZWxsaSB3cm90ZToKPj4+Cj4+Pgo+Pj4gT24gMy8xOC8yMDIxIDEy OjE4IFBNLCBGbG9yaWFuIEZhaW5lbGxpIHdyb3RlOgo+Pj4+IEl0IG1heSBiZSB1c2VmdWwgdG8g ZGlzYWJsZSB0aGUgU1dJT1RMQiBjb21wbGV0ZWx5IGZvciB0ZXN0aW5nIG9yIHdoZW4gYQo+Pj4+ IHBsYXRmb3JtIGlzIGtub3duIG5vdCB0byBoYXZlIGFueSBEUkFNIGFkZHJlc3NpbmcgbGltaXRh dGlvbnMgd2hhdCBzbwo+Pj4+IGV2ZXIuCj4+Cj4+IElzbid0IHRoYXQgd2hhdCAic3dpb3RsYj1u b2ZvcmNlIiBpcyBmb3I/IElmIHlvdSdyZSBjb25maWRlbnQgdGhhdCB3ZSd2ZQo+PiByZWFsbHkg aXJvbmVkIG91dCAqYWxsKiB0aGUgYXdrd2FyZCBjb3JuZXJzIHRoYXQgdXNlZCB0byBibG93IHVw IGlmCj4+IHZhcmlvdXMgaW50ZXJuYWwgYml0cyB3ZXJlIGxlZnQgdW5pbml0aWFsaXNlZCwgdGhl biBpdCB3b3VsZCBtYWtlIHNlbnNlCj4+IHRvIGp1c3QgdHdlYWsgdGhlIGltcGxlbWVudGF0aW9u IG9mIHdoYXQgd2UgYWxyZWFkeSBoYXZlLgo+IAo+IHN3aW90bGI9bm9mb3JjZSBkb2VzIHByZXZl bnQgZG1hX2RpcmVjdF9tYXBfcGFnZSgpIGZyb20gcmVzb3J0aW5nIHRvIHRoZQo+IHN3aW90bGIs IGhvd2V2ZXIgd2hhdCBJIGFtIGFsc28gYWZ0ZXIgaXMgcmVjbGFpbWluZyB0aGVzZSA2NE1CIG9m Cj4gZGVmYXVsdCBTV0lPVExCIGJvdW5jZSBidWZmZXJpbmcgbWVtb3J5IGJlY2F1c2UgbXkgc3lz dGVtcyBydW4gd2l0aAo+IGxhcmdlIGFtb3VudHMgb2YgcmVzZXJ2ZWQgbWVtb3J5IGludG8gWk9O RV9NT1ZBQkxFIGFuZCBldmVyeXRoaW5nIGluCj4gWk9ORV9OT1JNQUwgaXMgcHJlY2lvdXMgYXQg dGhhdCBwb2ludC4KCkl0IGFsc28gZm9yY2VzIGlvX3RsYl9uc2xhYnMgdG8gdGhlIG1pbmltdW0s IHNvIGl0IHNob3VsZCBiZSBjbGFpbWluZyAKY29uc2lkZXJhYmx5IGxlc3MgdGhhbiA2NE1CLiBJ SVJDIHRoZSBvcmlnaW5hbCBwcm9wb3NhbCAqZGlkKiBza2lwIAppbml0aWFsaXNhdGlvbiBjb21w bGV0ZWx5LCBidXQgdGhhdCB0dXJuZWQgdXAgdGhlIGFmb3JlbWVudGlvbmVkIGlzc3Vlcy4KCj4+ IEkgd291bGRuJ3QgbmVjZXNzYXJpbHkgZGlzYWdyZWUgd2l0aCBhZGRpbmcgIm9mZiIgYXMgYW4g YWRkaXRpb25hbCBhbGlhcwo+PiBmb3IgIm5vZm9yY2UiLCB0aG91Z2gsIHNpbmNlIGl0IGRvZXMg Y29tZSBhY3Jvc3MgYXMgYSBiaXQgd2Fja3kgZm9yCj4+IGdlbmVyYWwgdXNlLgo+Pgo+Pj4+IFNp Z25lZC1vZmYtYnk6IEZsb3JpYW4gRmFpbmVsbGkgPGYuZmFpbmVsbGlAZ21haWwuY29tPgo+Pj4K Pj4+IENocmlzdG9waCwgaW4gYWRkaXRpb24gdG8gdGhpcyBjaGFuZ2UsIGhvdyB3b3VsZCB5b3Ug ZmVlbCBpZiB3ZQo+Pj4gcXVhbGlmaWVkIHRoZSBzd2lvdGxiX2luaXQoKSBpbiBhcmNoL2FybS9t bS9pbml0LmMgd2l0aCBhOgo+Pj4KPj4+Cj4+PiBpZiAobWVtYmxvY2tfZW5kX29mX0RSQU0oKSA+ PSBTWl80RykKPj4+ICDCoMKgwqDCoHN3aW90bGJfaW5pdCgxKQo+Pgo+PiBNb2R1bG8gInN3aW90 bGI9Zm9yY2UiLCBvZiBjb3Vyc2UgOykKPiAKPiBJbmRlZWQsIHdlIHdvdWxkIG5lZWQgdG8gaGFu ZGxlIHRoYXQgY2FzZSBhcyB3ZWxsLiBEb2VzIGl0IHNvdW5kCj4gcmVhc29uYWJsZSB0byBkbyB0 aGF0IHRvIHlvdSBhcyB3ZWxsPwoKSSB3b3VsZG4ndCBsaWtlIGl0IGRvbmUgdG8gbWUgcGVyc29u YWxseSwgYnV0IGZvciBhcm02NCwgb2JzZXJ2ZSB3aGF0IAptZW1faW5pdCgpIGluIGFyY2gvYXJt NjQvbW0vaW5pdC5jIGFscmVhZHkgZG9lcy4KClJvYmluLgpfX19fX19fX19fX19fX19fX19fX19f X19fX19fX19fX19fX19fX19fX19fX19fXwppb21tdSBtYWlsaW5nIGxpc3QKaW9tbXVAbGlzdHMu bGludXgtZm91bmRhdGlvbi5vcmcKaHR0cHM6Ly9saXN0cy5saW51eGZvdW5kYXRpb24ub3JnL21h aWxtYW4vbGlzdGluZm8vaW9tbXU=