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a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:mime-version:references:in-reply-to:from:date :message-id:subject:to:cc; bh=n3TBE7tx6S7GnpZVCrwlr/3N+oOzUPGbvusmUOmG/T0=; b=luneZbfF0Ieeiv3yoJQdxdMHLlpsFflbQJxkq02LUiNEMop2AqdwpffXOp17melaIJ cRKI1L2oHpLocEIcqcyhZjNAT6b206TcUl4z7m4fU3QnZoReJ5fWD90RYY45eREKTFGU yvwT43d2MUR4HFJ2Jcr6e5CW1sWoU9lLdSNxig4KfQDQKJjw7PU/PNrl1FYT4dFYvjE0 id+eOHO+f1NifjIBHnDZX44/IjcYYfYOvMmlCGLPASAgRgQWMIODCJ+dk8++e61Wxg/r rsyBdKWMES2Iv+b5Sf45c2GN7GQ82XxesnGBjrU74cbkYsxfCIJdO8IXE0A6dTD5r02Y zrKw== X-Gm-Message-State: AOAM532pdhSae7o11ZjJAxCE8jv+SSPfmHCciaLO9EPW0KWcfljZPeRa 62qb3QH6GPlOr9D/tRIYzmevQK/4AcZFdF6XnaeP+B6d X-Google-Smtp-Source: ABdhPJyrHWOsI7xCVBWiV5yZaFNfurId9widfkp7/AgosrKLWEbgVSdn17jhr9iXO5CndhUq8INILlVyez+GNc7k8GQ= X-Received: by 2002:aa7:da14:: with SMTP id r20mr3712651eds.7.1592577904398; Fri, 19 Jun 2020 07:45:04 -0700 (PDT) MIME-Version: 1.0 References: <20200619103636.11974-1-m.szyprowski@samsung.com> <20200619103636.11974-14-m.szyprowski@samsung.com> In-Reply-To: <20200619103636.11974-14-m.szyprowski@samsung.com> From: Rob Clark Date: Fri, 19 Jun 2020 07:45:32 -0700 Message-ID: Subject: Re: [PATCH v7 13/36] drm: msm: fix common struct sg_table related issues To: Marek Szyprowski Cc: freedreno , Bartlomiej Zolnierkiewicz , David Airlie , Sean Paul , Linux Kernel Mailing List , dri-devel , linaro-mm-sig@lists.linaro.org, "list@263.net:IOMMU DRIVERS , Joerg Roedel , " , Daniel Vetter , linux-arm-msm , Robin Murphy , Christoph Hellwig , "moderated list:ARM/FREESCALE IMX / MXC ARM ARCHITECTURE" X-BeenThere: iommu@lists.linux-foundation.org X-Mailman-Version: 2.1.15 Precedence: list List-Id: Development issues for Linux IOMMU support List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Errors-To: iommu-bounces@lists.linux-foundation.org Sender: "iommu" On Fri, Jun 19, 2020 at 3:37 AM Marek Szyprowski wrote: > > 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. > > Signed-off-by: Marek Szyprowski Acked-by: Rob Clark (let me know if you want me to take this one in via msm-next or if the plan is to take the series via drm-misc) > --- > drivers/gpu/drm/msm/msm_gem.c | 13 +++++-------- > drivers/gpu/drm/msm/msm_gpummu.c | 14 ++++++-------- > drivers/gpu/drm/msm/msm_iommu.c | 2 +- > 3 files changed, 12 insertions(+), 17 deletions(-) > > diff --git a/drivers/gpu/drm/msm/msm_gem.c b/drivers/gpu/drm/msm/msm_gem.c > index 38b0c0e1f83e..e0d5fd36ea8f 100644 > --- a/drivers/gpu/drm/msm/msm_gem.c > +++ b/drivers/gpu/drm/msm/msm_gem.c > @@ -53,11 +53,10 @@ static void sync_for_device(struct msm_gem_object *msm_obj) > struct device *dev = msm_obj->base.dev->dev; > > if (get_dma_ops(dev) && IS_ENABLED(CONFIG_ARM64)) { > - dma_sync_sg_for_device(dev, msm_obj->sgt->sgl, > - msm_obj->sgt->nents, DMA_BIDIRECTIONAL); > + dma_sync_sgtable_for_device(dev, msm_obj->sgt, > + DMA_BIDIRECTIONAL); > } else { > - dma_map_sg(dev, msm_obj->sgt->sgl, > - msm_obj->sgt->nents, DMA_BIDIRECTIONAL); > + dma_map_sgtable(dev, msm_obj->sgt, DMA_BIDIRECTIONAL, 0); > } > } > > @@ -66,11 +65,9 @@ static void sync_for_cpu(struct msm_gem_object *msm_obj) > struct device *dev = msm_obj->base.dev->dev; > > if (get_dma_ops(dev) && IS_ENABLED(CONFIG_ARM64)) { > - dma_sync_sg_for_cpu(dev, msm_obj->sgt->sgl, > - msm_obj->sgt->nents, DMA_BIDIRECTIONAL); > + dma_sync_sgtable_for_cpu(dev, msm_obj->sgt, DMA_BIDIRECTIONAL); > } else { > - dma_unmap_sg(dev, msm_obj->sgt->sgl, > - msm_obj->sgt->nents, DMA_BIDIRECTIONAL); > + dma_unmap_sgtable(dev, msm_obj->sgt, DMA_BIDIRECTIONAL, 0); > } > } > > diff --git a/drivers/gpu/drm/msm/msm_gpummu.c b/drivers/gpu/drm/msm/msm_gpummu.c > index 310a31b05faa..319f06c28235 100644 > --- a/drivers/gpu/drm/msm/msm_gpummu.c > +++ b/drivers/gpu/drm/msm/msm_gpummu.c > @@ -30,21 +30,19 @@ static int msm_gpummu_map(struct msm_mmu *mmu, uint64_t iova, > { > struct msm_gpummu *gpummu = to_msm_gpummu(mmu); > unsigned idx = (iova - GPUMMU_VA_START) / GPUMMU_PAGE_SIZE; > - struct scatterlist *sg; > + struct sg_dma_page_iter dma_iter; > unsigned prot_bits = 0; > - unsigned i, j; > > if (prot & IOMMU_WRITE) > prot_bits |= 1; > if (prot & IOMMU_READ) > prot_bits |= 2; > > - for_each_sg(sgt->sgl, sg, sgt->nents, i) { > - dma_addr_t addr = sg->dma_address; > - for (j = 0; j < sg->length / GPUMMU_PAGE_SIZE; j++, idx++) { > - gpummu->table[idx] = addr | prot_bits; > - addr += GPUMMU_PAGE_SIZE; > - } > + for_each_sgtable_dma_page(sgt, &dma_iter, 0) { > + dma_addr_t addr = sg_page_iter_dma_address(&dma_iter); > + > + BUILD_BUG_ON(GPUMMU_PAGE_SIZE != PAGE_SIZE); > + gpummu->table[idx++] = addr | prot_bits; > } > > /* we can improve by deferring flush for multiple map() */ > diff --git a/drivers/gpu/drm/msm/msm_iommu.c b/drivers/gpu/drm/msm/msm_iommu.c > index 3a381a9674c9..6c31e65834c6 100644 > --- a/drivers/gpu/drm/msm/msm_iommu.c > +++ b/drivers/gpu/drm/msm/msm_iommu.c > @@ -36,7 +36,7 @@ static int msm_iommu_map(struct msm_mmu *mmu, uint64_t iova, > struct msm_iommu *iommu = to_msm_iommu(mmu); > size_t ret; > > - ret = iommu_map_sg(iommu->domain, iova, sgt->sgl, sgt->nents, prot); > + ret = iommu_map_sgtable(iommu->domain, iova, sgt, prot); > WARN_ON(!ret); > > return (ret == len) ? 0 : -EINVAL; > -- > 2.17.1 > _______________________________________________ iommu mailing list iommu@lists.linux-foundation.org https://lists.linuxfoundation.org/mailman/listinfo/iommu