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Tue, 20 Nov 2018 14:49:46 +0000 Received: from userv0122.oracle.com (userv0122.oracle.com [156.151.31.75]) by aserv0021.oracle.com (8.14.4/8.14.4) with ESMTP id wAKEnjrN010619 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK); Tue, 20 Nov 2018 14:49:45 GMT Received: from abhmp0017.oracle.com (abhmp0017.oracle.com [141.146.116.23]) by userv0122.oracle.com (8.14.4/8.14.4) with ESMTP id wAKEniPr005325; Tue, 20 Nov 2018 14:49:44 GMT Received: from char.us.oracle.com (/10.152.32.25) by default (Oracle Beehive Gateway v4.0) with ESMTP ; Tue, 20 Nov 2018 06:49:44 -0800 Received: by char.us.oracle.com (Postfix, from userid 1000) id 38D206A00D4; Tue, 20 Nov 2018 09:49:43 -0500 (EST) Date: Tue, 20 Nov 2018 09:49:43 -0500 From: Konrad Rzeszutek Wilk To: Robin Murphy , sstabellini@kernel.org Cc: hch@lst.de, m.szyprowski@samsung.com, john.stultz@linaro.org, iommu@lists.linux-foundation.org, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH 2/2] swiotlb: Skip cache maintenance on map error Message-ID: <20181120144943.GI10917@char.us.oracle.com> References: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.8.3 (2017-05-23) X-Proofpoint-Virus-Version: vendor=nai engine=5900 definitions=9082 signatures=668683 X-Proofpoint-Spam-Details: rule=notspam policy=default score=0 suspectscore=0 malwarescore=0 phishscore=0 bulkscore=0 spamscore=0 mlxscore=0 mlxlogscore=999 adultscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.0.1-1810050000 definitions=main-1811200133 Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, Nov 20, 2018 at 02:09:53PM +0000, Robin Murphy wrote: > If swiotlb_bounce_page() failed, calling arch_sync_dma_for_device() may > lead to such delights as performing cache maintenance on whatever > address phys_to_virt(SWIOTLB_MAP_ERROR) looks like, which is typically > outside the kernel memory map and goes about as well as expected. > > Don't do that. +Stefano > > Fixes: a4a4330db46a ("swiotlb: add support for non-coherent DMA") > Signed-off-by: Robin Murphy > --- > kernel/dma/swiotlb.c | 3 ++- > 1 file changed, 2 insertions(+), 1 deletion(-) > > diff --git a/kernel/dma/swiotlb.c b/kernel/dma/swiotlb.c > index 5731daa09a32..045930e32c0e 100644 > --- a/kernel/dma/swiotlb.c > +++ b/kernel/dma/swiotlb.c > @@ -679,7 +679,8 @@ dma_addr_t swiotlb_map_page(struct device *dev, struct page *page, > } > > if (!dev_is_dma_coherent(dev) && > - (attrs & DMA_ATTR_SKIP_CPU_SYNC) == 0) > + (attrs & DMA_ATTR_SKIP_CPU_SYNC) == 0 && > + dev_addr != DIRECT_MAPPING_ERROR) > arch_sync_dma_for_device(dev, phys, size, dir); > > return dev_addr; > -- > 2.19.1.dirty >