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=-3.8 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,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 9ABD6C43467 for ; Thu, 8 Oct 2020 07:31:55 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 36F7C21897 for ; Thu, 8 Oct 2020 07:31:55 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=ffwll.ch header.i=@ffwll.ch header.b="dAa4Urod" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727190AbgJHHbv (ORCPT ); Thu, 8 Oct 2020 03:31:51 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:48402 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725849AbgJHHbv (ORCPT ); Thu, 8 Oct 2020 03:31:51 -0400 Received: from mail-oi1-x244.google.com (mail-oi1-x244.google.com [IPv6:2607:f8b0:4864:20::244]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id C06EEC0613D3 for ; Thu, 8 Oct 2020 00:31:49 -0700 (PDT) Received: by mail-oi1-x244.google.com with SMTP id l85so5322303oih.10 for ; Thu, 08 Oct 2020 00:31:49 -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=ogkw1NmOSWleETzvxYwVZZIizSINMS0qQkiw0aowwRQ=; b=dAa4UrodoeKqvvGBic2n/ikfUtGXIrA84JDvhHoeTG0wQyvzwM6zRb58ASAp90bOAP Z0Gq9W2/rAIbo9tt/Rdw3PX+Bn1vOefBbbpajIIFIeMsYr0JsELM1frkf/Q6RzY+4q6w KwDjwJvmHbSV+DyPoGD+FRH2axWgRzr70NSco= 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=ogkw1NmOSWleETzvxYwVZZIizSINMS0qQkiw0aowwRQ=; b=fUD9KvH9FrsXSJTrS417RK1oV+vl95MA6C4xXMoaSNm2BMsDPyKqtCfo590eOzmTbm 9bOd/1LQWYsbHN25rsgu20BcGOXCPliMP+Vn6ktNpj7POo3fyLDVUj4sLQaUjl7DxugK k3S9FkY3PWgAlH7sH28UNfMPFXjLa+VUe5kEsWaGhmb+9zEx3Tu/2Dopay23ze8Wj5hy hD4EuaWge3ZODE3d1HG2rDa5TGEYJNM9pTnklZMo/JkSny5lUBXQN8s9dAuxwf7P4Vcr wpxAsjHEf/BDHH17YtsP/ufn1dIaX6DTW2qyC653GFSdZv9req/U3N0R2SBAFlVGJlJA HkuQ== X-Gm-Message-State: AOAM533clXvLC5qFdbc6paB+P2M4vu8IHT/XTF5OB5KfHw1O7lSm8DOC +DO+XcIM5qT4cKLK0iaBlN5V6kvtY4oSbUSWwBQb4A== X-Google-Smtp-Source: ABdhPJx491RwkFJI9puzs4morldhkHhy8TQN885mw0wtSqvJNbvAlJbcViFwT+IWX3hheU/oD67HmER0Hab3kMQkGCo= X-Received: by 2002:aca:6083:: with SMTP id u125mr4379406oib.14.1602142309051; Thu, 08 Oct 2020 00:31:49 -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: <20201007232448.GC5177@ziepe.ca> From: Daniel Vetter Date: Thu, 8 Oct 2020 09:31:37 +0200 Message-ID: Subject: Re: [PATCH 10/13] PCI: revoke mappings like devmem To: Jason Gunthorpe Cc: Dan Williams , DRI Development , LKML , KVM list , Linux MM , Linux ARM , linux-samsung-soc , "Linux-media@vger.kernel.org" , linux-s390 , Daniel Vetter , Kees Cook , Andrew Morton , John Hubbard , =?UTF-8?B?SsOpcsO0bWUgR2xpc3Nl?= , Jan Kara , Bjorn Helgaas , Linux PCI Content-Type: text/plain; charset="UTF-8" Precedence: bulk List-ID: X-Mailing-List: kvm@vger.kernel.org On Thu, Oct 8, 2020 at 1:24 AM 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() > > Seems OK to use this more widely, but it feels a bit weird to live in > char/memory.c. > > 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 Yeah moving it to iomem and renaming it to have an iomem_prefix instead of devmem sounds like a good idea. -Daniel -- Daniel Vetter Software Engineer, Intel Corporation http://blog.ffwll.ch