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=-15.2 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,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 3303BC48BE6 for ; Mon, 14 Jun 2021 06:25:57 +0000 (UTC) Received: from lists.ozlabs.org (lists.ozlabs.org [112.213.38.117]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id CDD8E6120E for ; Mon, 14 Jun 2021 06:25:56 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org CDD8E6120E Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=lst.de Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=linuxppc-dev-bounces+linuxppc-dev=archiver.kernel.org@lists.ozlabs.org Received: from boromir.ozlabs.org (localhost [IPv6:::1]) by lists.ozlabs.org (Postfix) with ESMTP id 4G3M040Flhz309y for ; Mon, 14 Jun 2021 16:25:56 +1000 (AEST) Authentication-Results: lists.ozlabs.org; spf=none (no SPF record) smtp.mailfrom=lst.de (client-ip=213.95.11.211; helo=verein.lst.de; envelope-from=hch@lst.de; receiver=) Received: from verein.lst.de (verein.lst.de [213.95.11.211]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by lists.ozlabs.org (Postfix) with ESMTPS id 4G3Lzg2g1Dz2xgN for ; Mon, 14 Jun 2021 16:25:35 +1000 (AEST) Received: by verein.lst.de (Postfix, from userid 2407) id BF02567373; Mon, 14 Jun 2021 08:25:30 +0200 (CEST) Date: Mon, 14 Jun 2021 08:25:30 +0200 From: Christoph Hellwig To: Claire Chang Subject: Re: [PATCH v9 07/14] swiotlb: Bounce data from/to restricted DMA pool if available Message-ID: <20210614062530.GG28343@lst.de> References: <20210611152659.2142983-1-tientzu@chromium.org> <20210611152659.2142983-8-tientzu@chromium.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20210611152659.2142983-8-tientzu@chromium.org> User-Agent: Mutt/1.5.17 (2007-11-01) X-BeenThere: linuxppc-dev@lists.ozlabs.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: heikki.krogerus@linux.intel.com, thomas.hellstrom@linux.intel.com, peterz@infradead.org, joonas.lahtinen@linux.intel.com, dri-devel@lists.freedesktop.org, chris@chris-wilson.co.uk, grant.likely@arm.com, paulus@samba.org, Frank Rowand , mingo@kernel.org, Marek Szyprowski , sstabellini@kernel.org, Saravana Kannan , Joerg Roedel , "Rafael J . Wysocki" , Christoph Hellwig , Bartosz Golaszewski , bskeggs@redhat.com, linux-pci@vger.kernel.org, xen-devel@lists.xenproject.org, Thierry Reding , intel-gfx@lists.freedesktop.org, matthew.auld@intel.com, linux-devicetree , jxgao@google.com, daniel@ffwll.ch, Will Deacon , Konrad Rzeszutek Wilk , maarten.lankhorst@linux.intel.com, airlied@linux.ie, Dan Williams , linuxppc-dev@lists.ozlabs.org, jani.nikula@linux.intel.com, Rob Herring , rodrigo.vivi@intel.com, bhelgaas@google.com, boris.ostrovsky@oracle.com, Andy Shevchenko , jgross@suse.com, Nicolas Boichat , Greg KH , Randy Dunlap , lkml , tfiga@chromium.org, "list@263.net:IOMMU DRIVERS" , Jim Quinlan , xypron.glpk@gmx.de, Robin Murphy , bauerman@linux.ibm.com Errors-To: linuxppc-dev-bounces+linuxppc-dev=archiver.kernel.org@lists.ozlabs.org Sender: "Linuxppc-dev" On Fri, Jun 11, 2021 at 11:26:52PM +0800, Claire Chang wrote: > Regardless of swiotlb setting, the restricted DMA pool is preferred if > available. > > The restricted DMA pools provide a basic level of protection against the > DMA overwriting buffer contents at unexpected times. However, to protect > against general data leakage and system memory corruption, the system > needs to provide a way to lock down the memory access, e.g., MPU. > > Note that is_dev_swiotlb_force doesn't check if > swiotlb_force == SWIOTLB_FORCE. Otherwise the memory allocation behavior > with default swiotlb will be changed by the following patche > ("dma-direct: Allocate memory from restricted DMA pool if available"). > > Signed-off-by: Claire Chang > --- > include/linux/swiotlb.h | 10 +++++++++- > kernel/dma/direct.c | 3 ++- > kernel/dma/direct.h | 3 ++- > kernel/dma/swiotlb.c | 1 + > 4 files changed, 14 insertions(+), 3 deletions(-) > > diff --git a/include/linux/swiotlb.h b/include/linux/swiotlb.h > index 06cf17a80f5c..8200c100fe10 100644 > --- a/include/linux/swiotlb.h > +++ b/include/linux/swiotlb.h > @@ -85,6 +85,7 @@ extern enum swiotlb_force swiotlb_force; > * unmap calls. > * @debugfs: The dentry to debugfs. > * @late_alloc: %true if allocated using the page allocator > + * @force_swiotlb: %true if swiotlb is forced > */ > struct io_tlb_mem { > phys_addr_t start; > @@ -95,6 +96,7 @@ struct io_tlb_mem { > spinlock_t lock; > struct dentry *debugfs; > bool late_alloc; > + bool force_swiotlb; > struct io_tlb_slot { > phys_addr_t orig_addr; > size_t alloc_size; > @@ -115,6 +117,11 @@ static inline void swiotlb_set_io_tlb_default_mem(struct device *dev) > dev->dma_io_tlb_mem = io_tlb_default_mem; > } > > +static inline bool is_dev_swiotlb_force(struct device *dev) > +{ > + return dev->dma_io_tlb_mem->force_swiotlb; > +} > + > void __init swiotlb_exit(void); > unsigned int swiotlb_max_segment(void); > size_t swiotlb_max_mapping_size(struct device *dev); > @@ -126,8 +133,9 @@ static inline bool is_swiotlb_buffer(struct device *dev, phys_addr_t paddr) > { > return false; > } > -static inline void swiotlb_set_io_tlb_default_mem(struct device *dev) > +static inline bool is_dev_swiotlb_force(struct device *dev) > { > + return false; > } > static inline void swiotlb_exit(void) > { > diff --git a/kernel/dma/direct.c b/kernel/dma/direct.c > index 7a88c34d0867..078f7087e466 100644 > --- a/kernel/dma/direct.c > +++ b/kernel/dma/direct.c > @@ -496,7 +496,8 @@ size_t dma_direct_max_mapping_size(struct device *dev) > { > /* If SWIOTLB is active, use its maximum mapping size */ > if (is_swiotlb_active(dev) && > - (dma_addressing_limited(dev) || swiotlb_force == SWIOTLB_FORCE)) > + (dma_addressing_limited(dev) || swiotlb_force == SWIOTLB_FORCE || > + is_dev_swiotlb_force(dev))) I think we can remove the extra swiotlb_force check here if the swiotlb_force setting is propagated into io_tlb_default_mem->force when that is initialized. This avoids an extra check in the fast path. > - if (unlikely(swiotlb_force == SWIOTLB_FORCE)) > + if (unlikely(swiotlb_force == SWIOTLB_FORCE) || > + is_dev_swiotlb_force(dev)) Same here.