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=-6.8 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_PASS,URIBL_BLOCKED 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 09BC4C43382 for ; Thu, 27 Sep 2018 14:58:10 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id AF1FE21582 for ; Thu, 27 Sep 2018 14:58:09 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org AF1FE21582 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=arm.com Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727675AbeI0VQq (ORCPT ); Thu, 27 Sep 2018 17:16:46 -0400 Received: from foss.arm.com ([217.140.101.70]:35922 "EHLO foss.arm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727076AbeI0VQq (ORCPT ); Thu, 27 Sep 2018 17:16:46 -0400 Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.72.51.249]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id 3F36B7A9; Thu, 27 Sep 2018 07:58:07 -0700 (PDT) Received: from [10.4.12.131] (e110467-lin.Emea.Arm.com [10.4.12.131]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id DAB033F5BD; Thu, 27 Sep 2018 07:58:05 -0700 (PDT) Subject: Re: [PATCH 4/5] dma-direct: implement complete bus_dma_mask handling To: Christoph Hellwig , iommu@lists.linux-foundation.org Cc: Marek Szyprowski , Benjamin Herrenschmidt , Greg Kroah-Hartman , linux-kernel@vger.kernel.org, linuxppc-dev@lists.ozlabs.org References: <20180920185247.20037-1-hch@lst.de> <20180920185247.20037-5-hch@lst.de> From: Robin Murphy Message-ID: Date: Thu, 27 Sep 2018 15:58:04 +0100 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:52.0) Gecko/20100101 Thunderbird/52.9.1 MIME-Version: 1.0 In-Reply-To: <20180920185247.20037-5-hch@lst.de> Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-GB Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 20/09/18 19:52, Christoph Hellwig wrote: > Instead of rejecting devices with a too small bus_dma_mask we can handle > by taking the bus dma_mask into account for allocations and bounce > buffering decisions. > > Signed-off-by: Christoph Hellwig > --- > include/linux/dma-direct.h | 3 ++- > kernel/dma/direct.c | 21 +++++++++++---------- > 2 files changed, 13 insertions(+), 11 deletions(-) > > diff --git a/include/linux/dma-direct.h b/include/linux/dma-direct.h > index b79496d8c75b..fbca184ff5a0 100644 > --- a/include/linux/dma-direct.h > +++ b/include/linux/dma-direct.h > @@ -27,7 +27,8 @@ static inline bool dma_capable(struct device *dev, dma_addr_t addr, size_t size) > if (!dev->dma_mask) > return false; > > - return addr + size - 1 <= *dev->dma_mask; > + return addr + size - 1 <= > + min_not_zero(*dev->dma_mask, dev->bus_dma_mask); > } > #endif /* !CONFIG_ARCH_HAS_PHYS_TO_DMA */ > > diff --git a/kernel/dma/direct.c b/kernel/dma/direct.c > index 3c404e33d946..64466b7ef67b 100644 > --- a/kernel/dma/direct.c > +++ b/kernel/dma/direct.c > @@ -43,10 +43,11 @@ check_addr(struct device *dev, dma_addr_t dma_addr, size_t size, > return false; > } > > - if (*dev->dma_mask >= DMA_BIT_MASK(32)) { > + if (*dev->dma_mask >= DMA_BIT_MASK(32) || dev->bus_dma_mask) { Hmm... say *dev->dma_mask is 31 bits and dev->bus_dma_mask is 40 bits due to a global DT property, we'll now scream where we didn't before even though the bus mask is almost certainly irrelevant - is that desirable? > dev_err(dev, > - "%s: overflow %pad+%zu of device mask %llx\n", > - caller, &dma_addr, size, *dev->dma_mask); > + "%s: overflow %pad+%zu of device mask %llx bus mask %llx\n", > + caller, &dma_addr, size, > + *dev->dma_mask, dev->bus_dma_mask); > } > return false; > } > @@ -65,12 +66,18 @@ u64 dma_direct_get_required_mask(struct device *dev) > { > u64 max_dma = phys_to_dma_direct(dev, (max_pfn - 1) << PAGE_SHIFT); > > + if (dev->bus_dma_mask && dev->bus_dma_mask < max_dma) > + max_dma = dev->bus_dma_mask; Again, I think we could just do another min_not_zero() here. A device wired to address only one single page of RAM isn't a realistic prospect (and we could just flip the -1 and the shift in the max_dma calculation if we *really* wanted to support such things). > + > return (1ULL << (fls64(max_dma) - 1)) * 2 - 1; > } > > static gfp_t __dma_direct_optimal_gfp_mask(struct device *dev, u64 dma_mask, > u64 *phys_mask) > { > + if (dev->bus_dma_mask && dev->bus_dma_mask < dma_mask) > + dma_mask = dev->bus_dma_mask; > + Similarly, can't we assume dma_mask to be nonzero here too? It feels like we really shouldn't have managed to get this far without one. Robin. > if (force_dma_unencrypted()) > *phys_mask = __dma_to_phys(dev, dma_mask); > else > @@ -87,7 +94,7 @@ static gfp_t __dma_direct_optimal_gfp_mask(struct device *dev, u64 dma_mask, > static bool dma_coherent_ok(struct device *dev, phys_addr_t phys, size_t size) > { > return phys_to_dma_direct(dev, phys) + size - 1 <= > - dev->coherent_dma_mask; > + min_not_zero(dev->coherent_dma_mask, dev->bus_dma_mask); > } > > void *dma_direct_alloc_pages(struct device *dev, size_t size, > @@ -291,12 +298,6 @@ int dma_direct_supported(struct device *dev, u64 mask) > if (mask < phys_to_dma(dev, DMA_BIT_MASK(32))) > return 0; > #endif > - /* > - * Upstream PCI/PCIe bridges or SoC interconnects may not carry > - * as many DMA address bits as the device itself supports. > - */ > - if (dev->bus_dma_mask && mask > dev->bus_dma_mask) > - return 0; > return 1; > } > >