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 5A45BC43382 for ; Thu, 27 Sep 2018 14:30:26 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 02EA62159D for ; Thu, 27 Sep 2018 14:30:26 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 02EA62159D 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 S1727599AbeI0Us4 (ORCPT ); Thu, 27 Sep 2018 16:48:56 -0400 Received: from foss.arm.com ([217.140.101.70]:35568 "EHLO foss.arm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727280AbeI0Us4 (ORCPT ); Thu, 27 Sep 2018 16:48:56 -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 28E737A9; Thu, 27 Sep 2018 07:30:23 -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 BEA6E3F5BD; Thu, 27 Sep 2018 07:30:21 -0700 (PDT) Subject: Re: [PATCH 3/5] dma-direct: refine dma_direct_alloc zone selection 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> <20180920185247.20037-4-hch@lst.de> From: Robin Murphy Message-ID: Date: Thu, 27 Sep 2018 15:30:20 +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: <20180920185247.20037-4-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: > We need to take the DMA offset and encryption bit into account when > selecting a zone. User the opportunity to factor out the zone > selection into a helper for reuse. > > Signed-off-by: Christoph Hellwig > --- > kernel/dma/direct.c | 31 +++++++++++++++++++++---------- > 1 file changed, 21 insertions(+), 10 deletions(-) > > diff --git a/kernel/dma/direct.c b/kernel/dma/direct.c > index 81b73a5bba54..3c404e33d946 100644 > --- a/kernel/dma/direct.c > +++ b/kernel/dma/direct.c > @@ -68,6 +68,22 @@ u64 dma_direct_get_required_mask(struct device *dev) > 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 (force_dma_unencrypted()) > + *phys_mask = __dma_to_phys(dev, dma_mask); > + else > + *phys_mask = dma_to_phys(dev, dma_mask); Maybe make phys_to_dma_direct() take u64 instead of phys_addr_t so we can reuse it here? > + /* GFP_DMA32 and GFP_DMA are no ops without the corresponding zones: */ > + if (*phys_mask <= DMA_BIT_MASK(ARCH_ZONE_DMA_BITS)) > + return GFP_DMA; If we don't have ZONE_DMA it would in theory be a tiny bit better to fall back to GFP_DMA32 instead of returning 0 here, but I'm not sure it's worth the bother. > + if (*phys_mask <= DMA_BIT_MASK(32)) > + return GFP_DMA32; > + return 0; > +} > + > static bool dma_coherent_ok(struct device *dev, phys_addr_t phys, size_t size) > { > return phys_to_dma_direct(dev, phys) + size - 1 <= > @@ -80,17 +96,13 @@ void *dma_direct_alloc_pages(struct device *dev, size_t size, > unsigned int count = PAGE_ALIGN(size) >> PAGE_SHIFT; > int page_order = get_order(size); > struct page *page = NULL; > + u64 phys_mask; > void *ret; > > /* we always manually zero the memory once we are done: */ > gfp &= ~__GFP_ZERO; > - > - /* GFP_DMA32 and GFP_DMA are no ops without the corresponding zones: */ > - if (dev->coherent_dma_mask <= DMA_BIT_MASK(ARCH_ZONE_DMA_BITS)) > - gfp |= GFP_DMA; > - if (dev->coherent_dma_mask <= DMA_BIT_MASK(32) && !(gfp & GFP_DMA)) > - gfp |= GFP_DMA32; > - > + gfp |= __dma_direct_optimal_gfp_mask(dev, dev->coherent_dma_mask, > + &phys_mask); > again: > /* CMA can be used only in the context which permits sleeping */ > if (gfpflags_allow_blocking(gfp)) { > @@ -109,15 +121,14 @@ void *dma_direct_alloc_pages(struct device *dev, size_t size, > page = NULL; > > if (IS_ENABLED(CONFIG_ZONE_DMA32) && > - dev->coherent_dma_mask < DMA_BIT_MASK(64) && > + phys_mask < DMA_BIT_MASK(64) && > !(gfp & (GFP_DMA32 | GFP_DMA))) { > gfp |= GFP_DMA32; > goto again; Ah right, in that situation we should probably end up here anyway, so that's good enough - definitely not worth any more #ifdeffery above. Nits aside, Reviewed-by: Robin Murphy > } > > if (IS_ENABLED(CONFIG_ZONE_DMA) && > - dev->coherent_dma_mask < DMA_BIT_MASK(32) && > - !(gfp & GFP_DMA)) { > + phys_mask < DMA_BIT_MASK(32) && !(gfp & GFP_DMA)) { > gfp = (gfp & ~GFP_DMA32) | GFP_DMA; > goto again; > } >