From patchwork Thu Jun 3 16:41:10 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Patchwork-Submitter: Daniel Vetter X-Patchwork-Id: 74777 Received: from vger.kernel.org ([23.128.96.18]) by www.linuxtv.org with esmtp (Exim 4.92) (envelope-from ) id 1loqQJ-000U84-2i; Thu, 03 Jun 2021 16:42:25 +0000 Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229812AbhFCQoF (ORCPT + 1 other); Thu, 3 Jun 2021 12:44:05 -0400 Received: from mail-wr1-f49.google.com ([209.85.221.49]:43569 "EHLO mail-wr1-f49.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229719AbhFCQoF (ORCPT ); Thu, 3 Jun 2021 12:44:05 -0400 Received: by mail-wr1-f49.google.com with SMTP id u7so1073895wrs.10 for ; Thu, 03 Jun 2021 09:42:20 -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:in-reply-to:references :mime-version:content-transfer-encoding; bh=2pe98/RoIUXzCDVRxl/xmCe1bCIiBUSFO5AAZsF4X4c=; b=W/cifPT7EZpt/9vHjGmYsuK0ro0zZT5FXpJklAznprHaeGKtvd6DvYDbQyzXHbdN3f p59wmn8/1vb+mfedSCf/Bryu9KWJcYmBZY4voTMuw55dIiic7YOsv2Grycgo6Ts8ggUx ZHAb0SaYd0CS0dvzPGL5P+J66BP4M0pYsm4bs= 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=2pe98/RoIUXzCDVRxl/xmCe1bCIiBUSFO5AAZsF4X4c=; b=PYkxlxF1WzwrtQcBqWFjVivmOmuXHsvULJ4irnUqKbMAssis4a//CUdvVv0RZO+xy3 szMdef6q3ms88kI0TpO3negNNNFDVi2lD7jQFiF0/JjiEBQ10cFhV0dBOpzcK1EB5Wbf O69cvFZIefPJeDZeWen9jOBqyDeoW/stSg8U5QM+qV1NURbz0dF+zSXCOos80BqKNXI6 1g9+SNIBIPb3+iqMQwhcpzGsXbZ4kUHu19IXLgZ7HNzNZEFIB5hp/Fj3Ege+J+9v2HSN outdv+3lH4d1nVt6+8UvpYbhGZnpow3zKY8zWQ7kMacFfF2fDAlTaT7TpcxyNgLfwkPP LyRA== X-Gm-Message-State: AOAM530EeJZyvidWZMxUdzRdBS2/IM+eMdiv0qjWH+eNEsOzIyUf295i 4VPmUhqMM1juR0QGf+OM9zuxrA== X-Google-Smtp-Source: ABdhPJzD/tlT71a+Zy3mCWcZmzUDwV8s7qYZLAtIZrQu7z9kQ184iUhM7haFAqZ1h4a5geonxQ7OFg== X-Received: by 2002:adf:ee50:: with SMTP id w16mr816579wro.187.1622738479941; Thu, 03 Jun 2021 09:41:19 -0700 (PDT) Received: from phenom.ffwll.local ([2a02:168:57f4:0:efd0:b9e5:5ae6:c2fa]) by smtp.gmail.com with ESMTPSA id s28sm4992683wra.54.2021.06.03.09.41.19 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 03 Jun 2021 09:41:19 -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 v3 1/4] dma-buf: Require VM_PFNMAP vma for mmap Date: Thu, 3 Jun 2021 18:41:10 +0200 Message-Id: <20210603164113.1433476-2-daniel.vetter@ffwll.ch> X-Mailer: git-send-email 2.31.0 In-Reply-To: <20210603164113.1433476-1-daniel.vetter@ffwll.ch> References: <20210603164113.1433476-1-daniel.vetter@ffwll.ch> 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. 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 --- 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 eadd1eaa2fb5..dda583fb1f03 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);