From patchwork Tue Jul 13 20:51:50 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Patchwork-Submitter: Daniel Vetter X-Patchwork-Id: 75752 Received: from vger.kernel.org ([23.128.96.18]) by www.linuxtv.org with esmtp (Exim 4.92) (envelope-from ) id 1m3PNs-0068Cs-9c; Tue, 13 Jul 2021 20:52:06 +0000 Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S235460AbhGMUyw (ORCPT + 1 other); Tue, 13 Jul 2021 16:54:52 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:47358 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S235529AbhGMUyw (ORCPT ); Tue, 13 Jul 2021 16:54:52 -0400 Received: from mail-wr1-x42a.google.com (mail-wr1-x42a.google.com [IPv6:2a00:1450:4864:20::42a]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 8EE32C0613EE for ; Tue, 13 Jul 2021 13:52:01 -0700 (PDT) Received: by mail-wr1-x42a.google.com with SMTP id d12so336726wre.13 for ; Tue, 13 Jul 2021 13:52:01 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=ffwll.ch; s=google; h=from:to:cc:subject:date:message-id:in-reply-to:references :mime-version:content-transfer-encoding; bh=tb13L7U9dTCD6g70T53HTt4Zdsesm4ZnXBpaSFPW13w=; b=ZE05Y12a7V5jfYf3M4rfGrmXtIbZkpaEOKqRwBvqpdF6WVgvHYgmOlxZb0TrIWbDJg zJtba0xVTVEKWit7yauEX7Ll2j35Ys5tdQJsIFxi9ZsZiEHk2Byz55TIwiePzaPcddw0 2Q5Tyc2jB7dne2ntzJAvdaLzFnvt6NyLoLavw= X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:from:to:cc:subject:date:message-id:in-reply-to :references:mime-version:content-transfer-encoding; bh=tb13L7U9dTCD6g70T53HTt4Zdsesm4ZnXBpaSFPW13w=; b=AkHSKV1MjwVTHjtuB1bdjCiHAglZ2U7HgFfQVpoUJCOTib+VjziY7iP8FoDf3tJfrd Sh+DMoLFlK7QQTlaHcQvmTidkg59vnPKLw45pQYOFWKtDeaq+wcZzTEWfaIyis8QqeB6 QPrm3Ff4Ag1dnsH092s8/SGmEML3ogUKk2WFao2bYKmRH85pKknujw5NjIfXC3NTK5H4 703ea85Ys+3lshMtPx7NK9YyiGCc1O27JyBcua0aZiOIv8o3dZyGygWYK9dupTLZBc6F 7q8Lv+qVS6qHXNon6b35fm82ceBXZ9E3UGJBMllqJAzmFsys+04n4+BaLryxIOlVlk0R jz4w== X-Gm-Message-State: AOAM530OcldzDw5LgzjOngeAo1WCuj6hmMubxgcl/RYlm2H608KDD0d4 9OgMocBhwSgzzHeq2dtdJuHwyw== X-Google-Smtp-Source: ABdhPJxGX+4VmTvtDaSQVeWu7iGnr3LK8JR8WmSYlC0KYNHOE/Vk7imGwykovjH8SkAWboZLaVyy7Q== X-Received: by 2002:a5d:4e43:: with SMTP id r3mr8165252wrt.132.1626209520157; Tue, 13 Jul 2021 13:52:00 -0700 (PDT) Received: from phenom.ffwll.local ([2a02:168:57f4:0:efd0:b9e5:5ae6:c2fa]) by smtp.gmail.com with ESMTPSA id j10sm18642249wrt.35.2021.07.13.13.51.59 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 13 Jul 2021 13:51:59 -0700 (PDT) From: Daniel Vetter To: Intel Graphics Development Cc: DRI Development , Daniel Vetter , =?utf-8?q?Christian_K=C3=B6nig?= , Jason Gunthorpe , Suren Baghdasaryan , Matthew Wilcox , John Stultz , Daniel Vetter , Sumit Semwal , linux-media@vger.kernel.org, linaro-mm-sig@lists.linaro.org Subject: [PATCH v4 1/4] dma-buf: Require VM_PFNMAP vma for mmap Date: Tue, 13 Jul 2021 22:51:50 +0200 Message-Id: <20210713205153.1896059-2-daniel.vetter@ffwll.ch> X-Mailer: git-send-email 2.32.0 In-Reply-To: <20210713205153.1896059-1-daniel.vetter@ffwll.ch> References: <20210713205153.1896059-1-daniel.vetter@ffwll.ch> MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: linux-media@vger.kernel.org X-LSpam-Score: -2.5 (--) X-LSpam-Report: No, score=-2.5 required=5.0 tests=BAYES_00=-1.9,DKIM_SIGNED=0.1,DKIM_VALID=-0.1,DKIM_VALID_AU=-0.1,HEADER_FROM_DIFFERENT_DOMAINS=0.5,MAILING_LIST_MULTI=-1,RCVD_IN_DNSWL_NONE=-0.0001 autolearn=ham autolearn_force=no tldr; DMA buffers aren't normal memory, expecting that you can use them like that (like calling get_user_pages works, or that they're accounting like any other normal memory) cannot be guaranteed. Since some userspace only runs on integrated devices, where all buffers are actually all resident system memory, there's a huge temptation to assume that a struct page is always present and useable like for any more pagecache backed mmap. This has the potential to result in a uapi nightmare. To stop this gap require that DMA buffer mmaps are VM_PFNMAP, which blocks get_user_pages and all the other struct page based infrastructure for everyone. In spirit this is the uapi counterpart to the kernel-internal CONFIG_DMABUF_DEBUG. Motivated by a recent patch which wanted to swich the system dma-buf heap to vm_insert_page instead of vm_insert_pfn. v2: Jason brought up that we also want to guarantee that all ptes have the pte_special flag set, to catch fast get_user_pages (on architectures that support this). Allowing VM_MIXEDMAP (like VM_SPECIAL does) would still allow vm_insert_page, but limiting to VM_PFNMAP will catch that. From auditing the various functions to insert pfn pte entires (vm_insert_pfn_prot, remap_pfn_range and all it's callers like dma_mmap_wc) it looks like VM_PFNMAP is already required anyway, so this should be the correct flag to check for. References: https://lore.kernel.org/lkml/CAKMK7uHi+mG0z0HUmNt13QCCvutuRVjpcR0NjRL12k-WbWzkRg@mail.gmail.com/ Acked-by: Christian König Cc: Jason Gunthorpe Cc: Suren Baghdasaryan Cc: Matthew Wilcox Cc: John Stultz Signed-off-by: Daniel Vetter Cc: Sumit Semwal Cc: "Christian König" Cc: linux-media@vger.kernel.org Cc: linaro-mm-sig@lists.linaro.org Acked-by: Thomas Zimmermann --- Resending this so I can test the next two patches for vgem/shmem in intel-gfx-ci. Last round failed somehow, but I can't repro that at all locally here. No immediate plans to merge this patch here since ttm isn't addressed yet (and there we have the hugepte issue, for which I don't think we have a clear consensus yet). -Daniel --- drivers/dma-buf/dma-buf.c | 15 +++++++++++++-- 1 file changed, 13 insertions(+), 2 deletions(-) diff --git a/drivers/dma-buf/dma-buf.c b/drivers/dma-buf/dma-buf.c index 510b42771974..65cbd7f0f16a 100644 --- a/drivers/dma-buf/dma-buf.c +++ b/drivers/dma-buf/dma-buf.c @@ -130,6 +130,7 @@ static struct file_system_type dma_buf_fs_type = { static int dma_buf_mmap_internal(struct file *file, struct vm_area_struct *vma) { struct dma_buf *dmabuf; + int ret; if (!is_dma_buf_file(file)) return -EINVAL; @@ -145,7 +146,11 @@ static int dma_buf_mmap_internal(struct file *file, struct vm_area_struct *vma) dmabuf->size >> PAGE_SHIFT) return -EINVAL; - return dmabuf->ops->mmap(dmabuf, vma); + ret = dmabuf->ops->mmap(dmabuf, vma); + + WARN_ON(!(vma->vm_flags & VM_PFNMAP)); + + return ret; } static loff_t dma_buf_llseek(struct file *file, loff_t offset, int whence) @@ -1276,6 +1281,8 @@ EXPORT_SYMBOL_GPL(dma_buf_end_cpu_access); int dma_buf_mmap(struct dma_buf *dmabuf, struct vm_area_struct *vma, unsigned long pgoff) { + int ret; + if (WARN_ON(!dmabuf || !vma)) return -EINVAL; @@ -1296,7 +1303,11 @@ int dma_buf_mmap(struct dma_buf *dmabuf, struct vm_area_struct *vma, vma_set_file(vma, dmabuf->file); vma->vm_pgoff = pgoff; - return dmabuf->ops->mmap(dmabuf, vma); + ret = dmabuf->ops->mmap(dmabuf, vma); + + WARN_ON(!(vma->vm_flags & VM_PFNMAP)); + + return ret; } EXPORT_SYMBOL_GPL(dma_buf_mmap);