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 57BA0C48BE6 for ; Mon, 14 Jun 2021 06:25:40 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 37DB36120E for ; Mon, 14 Jun 2021 06:25:40 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S232469AbhFNG1k (ORCPT ); Mon, 14 Jun 2021 02:27:40 -0400 Received: from verein.lst.de ([213.95.11.211]:42794 "EHLO verein.lst.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S232134AbhFNG1f (ORCPT ); Mon, 14 Jun 2021 02:27:35 -0400 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 Cc: Rob Herring , mpe@ellerman.id.au, Joerg Roedel , Will Deacon , Frank Rowand , Konrad Rzeszutek Wilk , boris.ostrovsky@oracle.com, jgross@suse.com, Christoph Hellwig , Marek Szyprowski , benh@kernel.crashing.org, paulus@samba.org, "list@263.net:IOMMU DRIVERS" , sstabellini@kernel.org, Robin Murphy , grant.likely@arm.com, xypron.glpk@gmx.de, Thierry Reding , mingo@kernel.org, bauerman@linux.ibm.com, peterz@infradead.org, Greg KH , Saravana Kannan , "Rafael J . Wysocki" , heikki.krogerus@linux.intel.com, Andy Shevchenko , Randy Dunlap , Dan Williams , Bartosz Golaszewski , linux-devicetree , lkml , linuxppc-dev@lists.ozlabs.org, xen-devel@lists.xenproject.org, Nicolas Boichat , Jim Quinlan , tfiga@chromium.org, bskeggs@redhat.com, bhelgaas@google.com, chris@chris-wilson.co.uk, daniel@ffwll.ch, airlied@linux.ie, dri-devel@lists.freedesktop.org, intel-gfx@lists.freedesktop.org, jani.nikula@linux.intel.com, jxgao@google.com, joonas.lahtinen@linux.intel.com, linux-pci@vger.kernel.org, maarten.lankhorst@linux.intel.com, matthew.auld@intel.com, rodrigo.vivi@intel.com, thomas.hellstrom@linux.intel.com 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) Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 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.