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 DDB05C04EBE for ; Thu, 8 Oct 2020 07:31:52 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id 292422173E for ; Thu, 8 Oct 2020 07:31:51 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=ffwll.ch header.i=@ffwll.ch header.b="dAa4Urod" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 292422173E Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=ffwll.ch Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=owner-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix) id 3FD716B005C; Thu, 8 Oct 2020 03:31:51 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 3AF016B005D; Thu, 8 Oct 2020 03:31:51 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 2A1266B0062; Thu, 8 Oct 2020 03:31:51 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0160.hostedemail.com [216.40.44.160]) by kanga.kvack.org (Postfix) with ESMTP id F19496B005C for ; Thu, 8 Oct 2020 03:31:50 -0400 (EDT) Received: from smtpin23.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay03.hostedemail.com (Postfix) with ESMTP id 8BEEF8249980 for ; Thu, 8 Oct 2020 07:31:50 +0000 (UTC) X-FDA: 77347938780.23.berry58_6200e29271d6 Received: from filter.hostedemail.com (10.5.16.251.rfc1918.com [10.5.16.251]) by smtpin23.hostedemail.com (Postfix) with ESMTP id 6F3643760C for ; Thu, 8 Oct 2020 07:31:50 +0000 (UTC) X-HE-Tag: berry58_6200e29271d6 X-Filterd-Recvd-Size: 5208 Received: from mail-oi1-f195.google.com (mail-oi1-f195.google.com [209.85.167.195]) by imf49.hostedemail.com (Postfix) with ESMTP for ; Thu, 8 Oct 2020 07:31:49 +0000 (UTC) Received: by mail-oi1-f195.google.com with SMTP id q136so4179097oic.8 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=fJlVQcV2/VM7LFnGi6TafAxgbtIjRxhkaxPPwz5pQQxiEO+Nux/x0cLAIjSHdnenQe 8gtVWL5ewP/3APGpmG0Gsq+AU7DZQJiqRUrS0IR4hYJIPMlJvovfQD8UZGp5QHimOqOx kPcrPvfJ3724j8OmPyIG5elooTR+equ9et2W257qNKL0P/rMYHdY+9fv6kp82+Pycuh0 vdFO9zcml3TcRCnXhlxlcT4Q5QCR/7kKRy27wBYr/ycegio3F+jOq2gRm8VlC3k5KT3C cLO2R4CUOmnzOD53TuMB+hmfEUPC1bEx8t1Jz+MOnazHeGBKiqL3ctpq8X+/qjXHCdDC GR1Q== X-Gm-Message-State: AOAM531INv7RfaV747qPdV9xm2VzCptYPfQA3JwcO/43UMilouK8cf5/ cbWrmrr2mkSeetTOrjADOjVkbtJ9ZMnqRS3TwBHMCA== 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" X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: 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