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=-13.8 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS 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 45EE7C432BE for ; Tue, 31 Aug 2021 23:05:05 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 17EE460200 for ; Tue, 31 Aug 2021 23:05:05 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S240464AbhHaXF7 (ORCPT ); Tue, 31 Aug 2021 19:05:59 -0400 Received: from rosenzweig.io ([138.197.143.207]:44804 "EHLO rosenzweig.io" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S240560AbhHaXF6 (ORCPT ); Tue, 31 Aug 2021 19:05:58 -0400 Date: Tue, 31 Aug 2021 17:30:18 -0400 From: Alyssa Rosenzweig To: Sven Peter Cc: iommu@lists.linux-foundation.org, Joerg Roedel , Will Deacon , Robin Murphy , Arnd Bergmann , Mohamed Mediouni , Alexander Graf , Hector Martin , linux-kernel@vger.kernel.org Subject: Re: [PATCH v2 3/8] iommu/dma: Disable get_sgtable for granule > PAGE_SIZE Message-ID: References: <20210828153642.19396-1-sven@svenpeter.dev> <20210828153642.19396-4-sven@svenpeter.dev> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20210828153642.19396-4-sven@svenpeter.dev> Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org I use this function for cross-device sharing on the M1 display driver. Arguably this is unsafe but it works on 16k kernels and if you want to test the function on 4k, you know where my code is. On Sat, Aug 28, 2021 at 05:36:37PM +0200, Sven Peter wrote: > Pretend that iommu_dma_get_sgtable is not implemented when > granule > PAGE_SIZE since I can neither test this function right now > nor do I fully understand how it is used. > > Signed-off-by: Sven Peter > --- > drivers/iommu/dma-iommu.c | 6 ++++++ > 1 file changed, 6 insertions(+) > > diff --git a/drivers/iommu/dma-iommu.c b/drivers/iommu/dma-iommu.c > index d6e273ec3de6..64fbd9236820 100644 > --- a/drivers/iommu/dma-iommu.c > +++ b/drivers/iommu/dma-iommu.c > @@ -1315,9 +1315,15 @@ static int iommu_dma_get_sgtable(struct device *dev, struct sg_table *sgt, > void *cpu_addr, dma_addr_t dma_addr, size_t size, > unsigned long attrs) > { > + struct iommu_domain *domain = iommu_get_dma_domain(dev); > + struct iommu_dma_cookie *cookie = domain->iova_cookie; > + struct iova_domain *iovad = &cookie->iovad; > struct page *page; > int ret; > > + if (iovad->granule > PAGE_SIZE) > + return -ENXIO; > + > if (IS_ENABLED(CONFIG_DMA_REMAP) && is_vmalloc_addr(cpu_addr)) { > struct page **pages = dma_common_find_pages(cpu_addr); > > -- > 2.25.1 >