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=-15.5 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,NICE_REPLY_A,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED, 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 6639AC433DB for ; Fri, 22 Jan 2021 14:44:27 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 47BE1239D1 for ; Fri, 22 Jan 2021 14:44:27 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728686AbhAVOoU (ORCPT ); Fri, 22 Jan 2021 09:44:20 -0500 Received: from foss.arm.com ([217.140.110.172]:51162 "EHLO foss.arm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728792AbhAVOm4 (ORCPT ); Fri, 22 Jan 2021 09:42:56 -0500 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 DB90D11B3; Fri, 22 Jan 2021 06:42:07 -0800 (PST) Received: from [10.57.39.58] (unknown [10.57.39.58]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 1B9853F66E; Fri, 22 Jan 2021 06:42:05 -0800 (PST) Subject: Re: [PATCH v2] ACPI/IORT: Do not blindly trust DMA masks from firmware To: Moritz Fischer , lorenzo.pieralisi@arm.com Cc: guohanjun@huawei.com, rjw@rjwysocki.net, linux-kernel@vger.kernel.org, linux-acpi@vger.kernel.org, moritzf@google.com, sudeep.holla@arm.com, will@kernel.org, linux-arm-kernel@lists.infradead.org References: <20210122012419.95010-1-mdf@kernel.org> From: Robin Murphy Message-ID: Date: Fri, 22 Jan 2021 14:42:05 +0000 User-Agent: Mozilla/5.0 (Windows NT 10.0; rv:78.0) Gecko/20100101 Thunderbird/78.6.1 MIME-Version: 1.0 In-Reply-To: <20210122012419.95010-1-mdf@kernel.org> Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-GB Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 2021-01-22 01:24, Moritz Fischer wrote: > Address issue observed on real world system with suboptimal IORT table > where DMA masks of PCI devices would get set to 0 as result. > > iort_dma_setup() would query the root complex'/named component IORT > entry for a DMA mask, and use that over the one the device has been > configured with earlier. > > Ideally we want to use the minimum mask of what the IORT contains for > the root complex and what the device was configured with. > > Fixes: 5ac65e8c8941 ("ACPI/IORT: Support address size limit for root complexes") > Signed-off-by: Moritz Fischer > --- > > Changes from v1: > - Changed warning to FW_BUG > - Warn for both Named Component or Root Complex > - Replaced min_not_zero() with min() > > --- > drivers/acpi/arm64/iort.c | 14 ++++++++++++-- > 1 file changed, 12 insertions(+), 2 deletions(-) > > diff --git a/drivers/acpi/arm64/iort.c b/drivers/acpi/arm64/iort.c > index d4eac6d7e9fb..2494138a6905 100644 > --- a/drivers/acpi/arm64/iort.c > +++ b/drivers/acpi/arm64/iort.c > @@ -1107,6 +1107,11 @@ static int nc_dma_get_range(struct device *dev, u64 *size) > > ncomp = (struct acpi_iort_named_component *)node->node_data; > > + if (!ncomp->memory_address_limit) { > + pr_warn(FW_BUG "Named component missing memory address limit\n"); > + return -EINVAL; > + } > + > *size = ncomp->memory_address_limit >= 64 ? U64_MAX : > 1ULL<memory_address_limit; > > @@ -1126,6 +1131,11 @@ static int rc_dma_get_range(struct device *dev, u64 *size) > > rc = (struct acpi_iort_root_complex *)node->node_data; > > + if (!rc->memory_address_limit) { > + pr_warn(FW_BUG "Root complex missing memory address limit\n"); > + return -EINVAL; > + } > + > *size = rc->memory_address_limit >= 64 ? U64_MAX : > 1ULL<memory_address_limit; > > @@ -1173,8 +1183,8 @@ void iort_dma_setup(struct device *dev, u64 *dma_addr, u64 *dma_size) > end = dmaaddr + size - 1; > mask = DMA_BIT_MASK(ilog2(end) + 1); > dev->bus_dma_limit = end; > - dev->coherent_dma_mask = mask; > - *dev->dma_mask = mask; > + dev->coherent_dma_mask = min(dev->coherent_dma_mask, mask); > + *dev->dma_mask = min(*dev->dma_mask, mask); Oops, I got so distracted by the "not_zero" aspect in v1 that I ended up thinking purely about smaller-than-default masks, but of course this *does* matter the other way round. And it is what we've always done on the DT side, so at least it makes us consistent. FWIW I've already started writing up a patch to kill off this bit entirely, but either way we still can't meaningfully interpret a supposed DMA limit of 0 bits in a table describing DMA-capable devices, so for this patch as a fix, Reviewed-by: Robin Murphy Thanks, Robin. > } > > *dma_addr = dmaaddr; >