From patchwork Thu Aug 12 13:14:09 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Patchwork-Submitter: Daniel Vetter X-Patchwork-Id: 76331 Received: from vger.kernel.org ([23.128.96.18]) by www.linuxtv.org with esmtp (Exim 4.92) (envelope-from ) id 1mEAXP-00CiDN-7h; Thu, 12 Aug 2021 13:14:27 +0000 Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S237043AbhHLNOq (ORCPT + 1 other); Thu, 12 Aug 2021 09:14:46 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:59158 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S236439AbhHLNOp (ORCPT ); Thu, 12 Aug 2021 09:14:45 -0400 Received: from mail-wm1-x32b.google.com (mail-wm1-x32b.google.com [IPv6:2a00:1450:4864:20::32b]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 8B16CC061765 for ; Thu, 12 Aug 2021 06:14:20 -0700 (PDT) Received: by mail-wm1-x32b.google.com with SMTP id 203-20020a1c00d40000b02902e6a4e244e4so4537070wma.4 for ; Thu, 12 Aug 2021 06:14:20 -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:mime-version :content-transfer-encoding; bh=dmErGBV7VXck18Gc2qFrnojMPrzyI2EPrDXNv3U1XmY=; b=CYOg+LUjp256t2um90jzwNbIMAWQqkmOEyFN5EaBp2h4O1nKvX8H8o+CpGJVu0cvra Bi59H593zFqTO0Tjipd0y7gxXb6Ue/uv7MOnvMvMSbigvqtdo3oKpION6K2wkaAQM/Ot psaWaQkhb4+YONaercPJtRtGxTcp9kDY4zUv0= 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:mime-version :content-transfer-encoding; bh=dmErGBV7VXck18Gc2qFrnojMPrzyI2EPrDXNv3U1XmY=; b=XMqzgEMniEoNv9yj4TIdtBPZuQooxaQ4GIGs489Y3TAhi/xbzA8MXNrdbBU+4pkI0S qJ1+NORaxLiq7nuCUitQo9w9LueZxKg+jTYYGjY7j2aIbWxe1SIRa5WtfNETD2sJtJr9 Mv6uiO4C4XpOzSDBOd1trUTnFOBxla+c3pyPbdXPeUDd9gAXclJu0xsb8MVj2tld6Y1s 1riib/EW1/ykoiwdv8k3qf0cAUAz6kzSB7JXFLwLQb89rF0U0vX2/QNESjWOnc5JRYfp CM/3311IXU81sxTXyt0OYL2nZOFH433v700aOrkdy8fjKDiBSBi8WlSGOUi4I+PA3Dzz k79A== X-Gm-Message-State: AOAM530RQ7s4EZoq7xDKCilAWN/4xox70mVJWpHRAFV79pahEd7ejdgF AS5v9LcI93zq+bNef/AQ1Eui1A== X-Google-Smtp-Source: ABdhPJwkvxrgUNLDCUG2WS460z2SKSCQl05C+7mRo54qZ58QNtO0XiYEVEgB1vN4eNSqQUwqOsYJGA== X-Received: by 2002:a1c:4e02:: with SMTP id g2mr15899917wmh.150.1628774059127; Thu, 12 Aug 2021 06:14:19 -0700 (PDT) Received: from phenom.ffwll.local ([2a02:168:57f4:0:efd0:b9e5:5ae6:c2fa]) by smtp.gmail.com with ESMTPSA id h4sm2914957wru.2.2021.08.12.06.14.18 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 12 Aug 2021 06:14:18 -0700 (PDT) From: Daniel Vetter To: DRI Development Cc: Intel Graphics Development , Daniel Vetter , =?utf-8?q?Christian_K=C3=B6nig?= , Thomas Zimmermann , 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 1/4] dma-buf: Require VM_PFNMAP vma for mmap Date: Thu, 12 Aug 2021 15:14:09 +0200 Message-Id: <20210812131412.2487363-1-daniel.vetter@ffwll.ch> X-Mailer: git-send-email 2.32.0 MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: linux-media@vger.kernel.org X-LSpam-Score: -3.2 (---) X-LSpam-Report: No, score=-3.2 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_LOW=-0.7 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. v3: Change to WARN_ON_ONCE (Thomas Zimmermann) References: https://lore.kernel.org/lkml/CAKMK7uHi+mG0z0HUmNt13QCCvutuRVjpcR0NjRL12k-WbWzkRg@mail.gmail.com/ Acked-by: Christian König Acked-by: Thomas Zimmermann Cc: Thomas Zimmermann 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 --- Resending this so I can test the next patches for vgem/shmem in intel-gfx-ci. 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 63d32261b63f..d19b1cf6c34f 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_ONCE(!(vma->vm_flags & VM_PFNMAP)); + + return ret; } static loff_t dma_buf_llseek(struct file *file, loff_t offset, int whence) @@ -1260,6 +1265,8 @@ 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; @@ -1280,7 +1287,11 @@ 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_ONCE(!(vma->vm_flags & VM_PFNMAP)); + + return ret; } EXPORT_SYMBOL_GPL(dma_buf_mmap);