From mboxrd@z Thu Jan 1 00:00:00 1970 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=-3.5 required=3.0 tests=BAYES_00,DKIM_INVALID, DKIM_SIGNED,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE, SPF_PASS,URIBL_BLOCKED autolearn=no 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 A4C15C433E7 for ; Thu, 8 Oct 2020 08:13:20 +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 3010A21927 for ; Thu, 8 Oct 2020 08:13:20 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=fail reason="signature verification failed" (1024-bit key) header.d=ffwll.ch header.i=@ffwll.ch header.b="hMW7zxgB" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 3010A21927 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=ffwll.ch Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=dri-devel-bounces@lists.freedesktop.org Received: from gabe.freedesktop.org (localhost [127.0.0.1]) by gabe.freedesktop.org (Postfix) with ESMTP id 6A80E6EA46; Thu, 8 Oct 2020 08:13:19 +0000 (UTC) Received: from mail-ot1-x341.google.com (mail-ot1-x341.google.com [IPv6:2607:f8b0:4864:20::341]) by gabe.freedesktop.org (Postfix) with ESMTPS id 5386B6EA46 for ; Thu, 8 Oct 2020 08:13:18 +0000 (UTC) Received: by mail-ot1-x341.google.com with SMTP id l4so4734345ota.7 for ; Thu, 08 Oct 2020 01:13:18 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=ffwll.ch; s=google; h=mime-version:references:in-reply-to:from:date:message-id:subject:to :cc; bh=6GE5pSnNRg0KlyvewB9QKOrrd6/Nut8BwJvyodyZJd4=; b=hMW7zxgBaxDt7Z8CMDWn3cCXSOY5QqOrFQ/uoN1baUlAIhOFYy+4SzujzZvv4Ur9FN onPuYsY03fgo4HL/In06Uiy/3ynGYwzwiQV3wfZ6whnso50XlzhHTRy/QZJCTuip3uEr ueKV+xdznXeh2dJB78HPK0Klt6lkMJnLUSyGA= X-Google-DKIM-Signature: v=1; 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=6GE5pSnNRg0KlyvewB9QKOrrd6/Nut8BwJvyodyZJd4=; b=oW8SWcsSPzAH4vh6d3QnvdVF0y66JIFXEW3dwON3H/Okk7hmPi2HSZHH8/4C7u46ZV vvnyCIb3lB95Op9yAHWy8CzI0vTjfPwx/R3I/DgsnjwRVIkiW3y6LSpuDMLK3cY9Ar8F 8UJsFM1e5+GudzCC1eTzlbeGOYgw1vVMWz9G1Kr3evIag2VhHIIj+Xjds8lXhzjdI24f 6jeOvRlbjwUCn5oAC7sA5sbrBw7eQRC6LI29lq5sgyQnyDCgjgC2qnONojpGfYpnkekv n0XZz3bIfwUOBuL/SfBq3xYj7oGOCSoXUUaMVkPJ8SG6nV6g+5+PuQsF9Y6MhZqITDq9 0u5Q== X-Gm-Message-State: AOAM532s0DSDQZ+SanA76aPwnAy9pb0mjj8hQGRvm9kEuC0JtXM/DAHQ 1B9WXMcM0nTG16Zz5uV5hOESi7BgeGUZsfOdMsRf4A== X-Google-Smtp-Source: ABdhPJzi+1LyDtM+RDWyhibTLQ/9o198dN3ibfXFnaztfI6BQhE6ckMA8Uych0T6Rb8ANf5SnQ1gmeZGjO89xISEbKU= X-Received: by 2002:a05:6830:1647:: with SMTP id h7mr4572127otr.281.1602144797647; Thu, 08 Oct 2020 01:13:17 -0700 (PDT) MIME-Version: 1.0 References: <20201007164426.1812530-1-daniel.vetter@ffwll.ch> <20201007164426.1812530-11-daniel.vetter@ffwll.ch> <20201007232448.GC5177@ziepe.ca> In-Reply-To: From: Daniel Vetter Date: Thu, 8 Oct 2020 10:13:06 +0200 Message-ID: Subject: Re: [PATCH 10/13] PCI: revoke mappings like devmem To: Dan Williams X-BeenThere: dri-devel@lists.freedesktop.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Direct Rendering Infrastructure - Development List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: linux-s390 , linux-samsung-soc , Jan Kara , Kees Cook , KVM list , Jason Gunthorpe , John Hubbard , LKML , DRI Development , Linux MM , =?UTF-8?B?SsOpcsO0bWUgR2xpc3Nl?= , Linux PCI , Bjorn Helgaas , Daniel Vetter , Andrew Morton , Linux ARM , "Linux-media@vger.kernel.org" Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Errors-To: dri-devel-bounces@lists.freedesktop.org Sender: "dri-devel" On Thu, Oct 8, 2020 at 9:50 AM Dan Williams wrote: > > On Wed, Oct 7, 2020 at 4:25 PM Jason Gunthorpe wrote: > > > > On Wed, Oct 07, 2020 at 12:33:06PM -0700, Dan Williams wrote: > > > On Wed, Oct 7, 2020 at 11:11 AM Daniel Vetter wrote: > > > > > > > > Since 3234ac664a87 ("/dev/mem: Revoke mappings when a driver claims > > > > the region") /dev/kmem zaps ptes when the kernel requests exclusive > > > > acccess to an iomem region. And with CONFIG_IO_STRICT_DEVMEM, this is > > > > the default for all driver uses. > > > > > > > > Except there's two more ways to access pci bars: sysfs and proc mmap > > > > support. Let's plug that hole. > > > > > > Ooh, yes, lets. > > > > > > > > > > > For revoke_devmem() to work we need to link our vma into the same > > > > address_space, with consistent vma->vm_pgoff. ->pgoff is already > > > > adjusted, because that's how (io_)remap_pfn_range works, but for the > > > > mapping we need to adjust vma->vm_file->f_mapping. Usually that's done > > > > at ->open time, but that's a bit tricky here with all the entry points > > > > and arch code. So instead create a fake file and adjust vma->vm_file. > > > > > > I don't think you want to share the devmem inode for this, this should > > > be based off the sysfs inode which I believe there is already only one > > > instance per resource. In contrast /dev/mem can have multiple inodes > > > because anyone can just mknod a new character device file, the same > > > problem does not exist for sysfs. > > > > The inode does not come from the filesystem char/mem.c creates a > > singular anon inode in devmem_init_inode() > > That's not quite right, An inode does come from the filesystem I just > arranged for that inode's i_mapping to be set to a common instance. > > > Seems OK to use this more widely, but it feels a bit weird to live in > > char/memory.c. > > Sure, now that more users have arrived it should move somewhere common. > > > This is what got me thinking maybe this needs to be a bit bigger > > generic infrastructure - eg enter this scheme from fops mmap and > > everything else is in mm/user_iomem.c > > It still requires every file that can map physical memory to have its > ->open fop do > > inode->i_mapping = devmem_inode->i_mapping; > filp->f_mapping = inode->i_mapping; > > I don't see how you can centralize that part. btw, why are you setting inode->i_mapping? The inode is already published, changing that looks risky. And I don't think it's needed, vma_link() only looks at filp->f_mapping, and in our drm_open() we only set that one. -Daniel -- Daniel Vetter Software Engineer, Intel Corporation http://blog.ffwll.ch _______________________________________________ dri-devel mailing list dri-devel@lists.freedesktop.org https://lists.freedesktop.org/mailman/listinfo/dri-devel