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Wed, 13 May 2020 13:33:23 +0000 (GMT) From: Marek Szyprowski To: dri-devel@lists.freedesktop.org, iommu@lists.linux-foundation.org, linaro-mm-sig@lists.linaro.org, linux-kernel@vger.kernel.org Subject: [PATCH v5 36/38] samples: vfio-mdev/mbochs: fix common struct sg_table related issues Date: Wed, 13 May 2020 15:32:43 +0200 Message-Id: <20200513133245.6408-36-m.szyprowski@samsung.com> X-Mailer: git-send-email 2.17.1 In-Reply-To: <20200513133245.6408-1-m.szyprowski@samsung.com> X-Brightmail-Tracker: H4sIAAAAAAAAA0WSa0hTYRzGeXcuOy5Pnabgi0XS0MgolxR6RMtCPxxSog+BEKWuPKjpvOw4 TSFamRVTlyahmZqYoum8tmZoeSudpZmpmddqaBcFzbxikbbtaH37vc//eXj+78tLIGIdZk+E R8WxiihZpAQXofqO1Z4DjiuNgQfrnwnp9J5XAro2pxqj1/WZCD2w9AOnH1W0C+jCZk86724s revKB/TigFFA100MYnR/Qx5OV74cF9Ktc5PYMZLRFmgB83y5EGXqlz9jzKdUg4B5XHyFGV2b QJisoVLANA6rcCY9eRZnNLpywCzU7Tq15YzIK4SNDI9nFdKjwaKwOVUHHmMUX2pSr2AqMLRN DawISB2GbzsaUDUQEWKqDEDN12HAHxYBbJyoxs0uMbUA4Id7bpuJd92ZQt5UCuCgdgHhTaZE WruPmXHKFapn1JawLZUCYGe6tTmAUIMCOPNnFjMPbKhg2F3ZLjQzSjlBo0FrYZI6Aq+maIR8 mwOsqGmxFFiZ9OmxZpTXm4Sw8D7Jsy+8XXsT49kGTht0G9mdsCsrzXI3SCUDaOypFPKHNAD7 r+UA3uUJx3p+mVYlTOs5w+oGKS8fh9/XZ1GzDKmtcGhmu1lGTHhHn43wMglv3RDz7j0w11D1 r7a1tw/hmYFF+qmNx3oBYElOAZIBHHL/lxUCUA7sWCUnD2U51yg2wYWTyTllVKjLhWh5HTD9 pa41w/xTsNR3vg1QBJBYk/RIY6AYk8VzifI2AAlEYkuerDZJZIgsMYlVRAcplJEs1wZ2EKjE jjxUNHVOTIXK4tgIlo1hFZtTAWFlrwJ2MSspfWpdgPe2Ip94Zzf6Y2cpuBjB/Xbxl/bimQEt vW7eSbspqV/o5GvdqKEk/qej/k1lnWeNJtVPOuK/JBStFjx0yC/2SKqNPZu57p4aNMoNP/AY VZ52KXNwytqvRqtOXM4p8bV9r1//In8yn6Fq+TaeUER2el3P7l1yd98rQbkwmes+RMHJ/gIq KpNhRwMAAA== X-Brightmail-Tracker: H4sIAAAAAAAAA+NgFprOIsWRmVeSWpSXmKPExsVy+t/xu7rK33fHGUyYq2fRe+4kk8XGGetZ Lf5vm8hsceXrezaLlauPMlks2G9tMWdqocWW03MZLb5cechksenxNVaLy7vmsFmsPXKX3eLg hyesDrwea+atYfTY+20Bi8f2bw9YPe53H2fy2Lyk3uP2v8fMHpNvLGf02H2zgc2jt/kdm0ff llWMHp83yQVwR+nZFOWXlqQqZOQXl9gqRRtaGOkZWlroGZlY6hkam8daGZkq6dvZpKTmZJal FunbJehlfGg4xlbwUKhiX9d31gbGG/xdjJwcEgImEhfPTGTvYuTiEBJYyihxas4EVoiEjMTJ aQ1QtrDEn2tdbBBFnxglNp1+xQ6SYBMwlOh6C5EQEehklJjW/REswSxwj0li7zo/EFtYIE7i 0K0+JhCbRUBV4uHxNWA1vAK2Eo2tfewQG+QlVm84wAxicwLFX93ZzwJiCwnkS+xdvI9tAiPf AkaGVYwiqaXFuem5xUZ6xYm5xaV56XrJ+bmbGIGRsu3Yzy07GLveBR9iFOBgVOLhtbi1O06I NbGsuDL3EKMEB7OSCK/feqAQb0piZVVqUX58UWlOavEhRlOgoyYyS4km5wOjOK8k3tDU0NzC 0tDc2NzYzEJJnLdD4GCMkEB6YklqdmpqQWoRTB8TB6dUA+M0pa8bnhzbMbOm4AFTgdZ+9dam VLsem4M/q0U/OCiZTbbPm3K+yuCF3cyoZqFv/b//PK3LcP6hlGVSHplUPnFPgwOv6pK9KYIv WPWyLmU4ikxd6vRWQSE2mvWbWmLkhLhb+2xkA1+mrcuTYxXZzJ+1VPbT4mUtL47FSu85cUho WcNFjktNXkosxRmJhlrMRcWJAIhhNxSqAgAA X-CMS-MailID: 20200513133323eucas1p1519f5901d2a4ee85b781fcc36e9601f7 X-Msg-Generator: CA X-RootMTR: 20200513133323eucas1p1519f5901d2a4ee85b781fcc36e9601f7 X-EPHeader: CA CMS-TYPE: 201P X-CMS-RootMailID: 20200513133323eucas1p1519f5901d2a4ee85b781fcc36e9601f7 References: <20200513132114.6046-1-m.szyprowski@samsung.com> <20200513133245.6408-1-m.szyprowski@samsung.com> X-BeenThere: dri-devel@lists.freedesktop.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Direct Rendering Infrastructure - Development List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: kvm@vger.kernel.org, Bartlomiej Zolnierkiewicz , David Airlie , Kirti Wankhede , Robin Murphy , Christoph Hellwig , linux-arm-kernel@lists.infradead.org, Marek Szyprowski MIME-Version: 1.0 Errors-To: dri-devel-bounces@lists.freedesktop.org Sender: "dri-devel" The Documentation/DMA-API-HOWTO.txt states that the dma_map_sg() function returns the number of the created entries in the DMA address space. However the subsequent calls to the dma_sync_sg_for_{device,cpu}() and dma_unmap_sg must be called with the original number of the entries passed to the dma_map_sg(). struct sg_table is a common structure used for describing a non-contiguous memory buffer, used commonly in the DRM and graphics subsystems. It consists of a scatterlist with memory pages and DMA addresses (sgl entry), as well as the number of scatterlist entries: CPU pages (orig_nents entry) and DMA mapped pages (nents entry). It turned out that it was a common mistake to misuse nents and orig_nents entries, calling DMA-mapping functions with a wrong number of entries or ignoring the number of mapped entries returned by the dma_map_sg() function. To avoid such issues, lets use a common dma-mapping wrappers operating directly on the struct sg_table objects and use scatterlist page iterators where possible. This, almost always, hides references to the nents and orig_nents entries, making the code robust, easier to follow and copy/paste safe. While touching this code, also add missing call to dma_unmap_sgtable. Signed-off-by: Marek Szyprowski --- For more information, see '[PATCH v5 00/38] DRM: fix struct sg_table nents vs. orig_nents misuse' thread: https://lore.kernel.org/linux-iommu/20200513132114.6046-1-m.szyprowski@samsung.com/T/ --- samples/vfio-mdev/mbochs.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) -- 1.9.1 _______________________________________________ dri-devel mailing list dri-devel@lists.freedesktop.org https://lists.freedesktop.org/mailman/listinfo/dri-devel diff --git a/samples/vfio-mdev/mbochs.c b/samples/vfio-mdev/mbochs.c index 3cc5e59..e030689 100644 --- a/samples/vfio-mdev/mbochs.c +++ b/samples/vfio-mdev/mbochs.c @@ -846,7 +846,7 @@ static struct sg_table *mbochs_map_dmabuf(struct dma_buf_attachment *at, if (sg_alloc_table_from_pages(sg, dmabuf->pages, dmabuf->pagecount, 0, dmabuf->mode.size, GFP_KERNEL) < 0) goto err2; - if (!dma_map_sg(at->dev, sg->sgl, sg->nents, direction)) + if (dma_map_sgtable(at->dev, sg, direction, 0)) goto err3; return sg; @@ -868,6 +868,7 @@ static void mbochs_unmap_dmabuf(struct dma_buf_attachment *at, dev_dbg(dev, "%s: %d\n", __func__, dmabuf->id); + dma_unmap_sgtable(at->dev, sg, direction, 0); sg_free_table(sg); kfree(sg); }