From patchwork Fri Feb 5 13:41:13 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Patchwork-Submitter: Daniel Vetter X-Patchwork-Id: 12070143 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=-16.5 required=3.0 tests=BAYES_00,DKIM_INVALID, DKIM_SIGNED,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,USER_AGENT_GIT 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 51383C433DB for ; Fri, 5 Feb 2021 13:41:26 +0000 (UTC) Received: from gabe.freedesktop.org (gabe.freedesktop.org [131.252.210.177]) (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 E9EBC64DA8 for ; Fri, 5 Feb 2021 13:41:25 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org E9EBC64DA8 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=ffwll.ch Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=intel-gfx-bounces@lists.freedesktop.org Received: from gabe.freedesktop.org (localhost [127.0.0.1]) by gabe.freedesktop.org (Postfix) with ESMTP id 1D67D6F41D; Fri, 5 Feb 2021 13:41:21 +0000 (UTC) Received: from mail-wm1-x336.google.com (mail-wm1-x336.google.com [IPv6:2a00:1450:4864:20::336]) by gabe.freedesktop.org (Postfix) with ESMTPS id 449106F41D for ; Fri, 5 Feb 2021 13:41:20 +0000 (UTC) Received: by mail-wm1-x336.google.com with SMTP id c127so5926613wmf.5 for ; Fri, 05 Feb 2021 05:41:20 -0800 (PST) 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=GCaPcXl/zVoyH5ug7imo/Ptsoxk4zPxmqCZda8+3vCk=; b=Lg5I//U+jhljDep/tZbtlTBpL5Gqws3LZ1vaFmypVkTv0Zi1lCd9nNxhtmfF2IqrE1 AQoLvMyrj7A6O41YXJiLwrrXzI1tgbvquIvcCydeB8vwCbH1Zfs/jKFez7Su+Qmo+EKL oFVBD8wgDQ3lhywMaJ/EF47zwno3jVpfMEiOg= 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=GCaPcXl/zVoyH5ug7imo/Ptsoxk4zPxmqCZda8+3vCk=; b=QPivwRIUi8JhoFxWYSBAVFnRxx6coBZryCldDS6eV/xO6gzj7lyrfL1gLFG9xo5W3n KMLSjCzWZ8qvbUcVAQHAAO5wUIT8V1c/6y+KkDXciDvQAvUk0f9Ius+KVddObegnE+E+ tT/UNe0tC9be9IvCL/3x/15MMEnv4ZmxWfoMqS8hIpnY4KB/MmQyFZvr7MtfUzdt0YV6 dhNzZkg88Ug5K1SJxLk4Ws8Lwh6YAXFFFhgoEpEWGO9ngPVbxpfV4IFkZgnCLYniX9/b a9LlA4BjlxUCfZ/ghdOvoeoVbxQYSqAcfPR0err0PtYRSuj5dK5bLRg1qdr/kwCZm7MV Bbeg== X-Gm-Message-State: AOAM533BhqsMp6qcGrXw0Z5kaRpTLR8dElTafN344e79KjTyPRG4OEc4 gdReQCaDFVWrmj10wK73OITiIw== X-Google-Smtp-Source: ABdhPJxrEXwkznYjeTT/T1bKOmAFxHx1aF6QSVq23Pt2SeXnxTFe4vLc0aqZqhVVuO6mujFzLCYWAA== X-Received: by 2002:a1c:2783:: with SMTP id n125mr3673907wmn.74.1612532478791; Fri, 05 Feb 2021 05:41:18 -0800 (PST) Received: from phenom.ffwll.local ([2a02:168:57f4:0:efd0:b9e5:5ae6:c2fa]) by smtp.gmail.com with ESMTPSA id b19sm8620382wmj.22.2021.02.05.05.41.17 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Fri, 05 Feb 2021 05:41:18 -0800 (PST) From: Daniel Vetter To: DRI Development Date: Fri, 5 Feb 2021 14:41:13 +0100 Message-Id: <20210205134113.2834980-1-daniel.vetter@ffwll.ch> X-Mailer: git-send-email 2.30.0 In-Reply-To: <20210203211948.2529297-1-daniel.vetter@ffwll.ch> References: <20210203211948.2529297-1-daniel.vetter@ffwll.ch> MIME-Version: 1.0 Subject: [Intel-gfx] [PATCH] RFC: dma-buf: Require VM_PFNMAP vma for mmap X-BeenThere: intel-gfx@lists.freedesktop.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Intel graphics driver community testing & development List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Daniel Vetter , Intel Graphics Development , Matthew Wilcox , =?utf-8?q?Christian_K=C3=B6nig?= , linaro-mm-sig@lists.linaro.org, Jason Gunthorpe , John Stultz , Daniel Vetter , Suren Baghdasaryan , Sumit Semwal , linux-media@vger.kernel.org Errors-To: intel-gfx-bounces@lists.freedesktop.org Sender: "Intel-gfx" 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/ 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: Christian König --- 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 f264b70c383e..06cb1d2e9fdc 100644 --- a/drivers/dma-buf/dma-buf.c +++ b/drivers/dma-buf/dma-buf.c @@ -127,6 +127,7 @@ 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; @@ -142,7 +143,11 @@ 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) @@ -1244,6 +1249,8 @@ 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; @@ -1264,7 +1271,11 @@ 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);