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=-15.8 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER, INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,URIBL_RED autolearn=unavailable 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 1834BC433E0 for ; Tue, 19 Jan 2021 22:37:14 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id E8A2023104 for ; Tue, 19 Jan 2021 22:37:13 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728640AbhASWhG (ORCPT ); Tue, 19 Jan 2021 17:37:06 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:54298 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2387677AbhASOhg (ORCPT ); Tue, 19 Jan 2021 09:37:36 -0500 Received: from mail-ot1-x333.google.com (mail-ot1-x333.google.com [IPv6:2607:f8b0:4864:20::333]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id DF895C0613ED for ; Tue, 19 Jan 2021 06:34:58 -0800 (PST) Received: by mail-ot1-x333.google.com with SMTP id 36so8416656otp.2 for ; Tue, 19 Jan 2021 06:34:58 -0800 (PST) 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:content-transfer-encoding; bh=4e0CGYDHUfu279fyABP5Y+REbie5VpiNs9f4Knw2Cok=; b=VBqn8DUOGeynSeRg3k1zvnxZgxHVN/m4CmDY5MHMndd1hrRsvbsOlsUR+N5zIlZNjv I1JtDyXv8bu7TYIBeBou0qbqzOTX9l2l0clQMWnlaS5BEAD0UdAQ7SGwdm49iZ4AHegS P3+zFz0CEInVbSD6li/gqZsMR+ZONkqJPxGNc= 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:content-transfer-encoding; bh=4e0CGYDHUfu279fyABP5Y+REbie5VpiNs9f4Knw2Cok=; b=AIW6Dpk4fpoMUfZByfEZw1ge2cB8GganhXqQguOJw1W34sMP9MkY7au2RPsGxUxxaa J/e285lUU8NkhmBdA8rXacXEgRpab1Xgv6t1FXyq86QCg/Qizgb2mOYe1Yhg4yHJDzJN CWQlDefgDgm6tlurUAhl2ZYjjPYw0um8a1AA4E30SiiqIYkAjl/+HR91Xcb8FcGTXR4R 1Yk5vQ2jGKJxG/o+sST5ZKY94h1db16HSmnCAk/eNZ9jd/Nr02+WAWwU3E7cOrmFpgJM W8alXHhO7xGR3EFW3l8qB86R0psnTKDr4hoFM1ruho6WAmGpgkWqd9RsMj1wGpEkXpkn /IMA== X-Gm-Message-State: AOAM533xLZRTZB2E/9EXbMd9CpzbsNIjzvT52z9pbbraqs/4Hyxd+gUv px/YbgDEchTfTqMRSlwG9U4uUOnNz2lKJsFJacYJIQ== X-Google-Smtp-Source: ABdhPJxNAs6mhMviXMtFn7M206VEX/Eake/mU9seAOwtJ76LA2Emqx8YbNqRC8ThlQu1JNtpKUawwkeGr99A8LNHJEY= X-Received: by 2002:a9d:ea6:: with SMTP id 35mr3626432otj.188.1611066898227; Tue, 19 Jan 2021 06:34:58 -0800 (PST) MIME-Version: 1.0 References: <20201127164131.2244124-1-daniel.vetter@ffwll.ch> <20201127164131.2244124-13-daniel.vetter@ffwll.ch> In-Reply-To: From: Daniel Vetter Date: Tue, 19 Jan 2021 15:34:47 +0100 Message-ID: Subject: Re: [PATCH v7 12/17] PCI: Revoke mappings like devmem To: Greg Kroah-Hartman Cc: DRI Development , LKML , Stephen Rothwell , KVM list , Linux MM , Linux ARM , linux-samsung-soc , "open list:DMA BUFFER SHARING FRAMEWORK" , Bjorn Helgaas , Dan Williams , Daniel Vetter , Jason Gunthorpe , Kees Cook , Andrew Morton , John Hubbard , =?UTF-8?B?SsOpcsO0bWUgR2xpc3Nl?= , Jan Kara , Linux PCI Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable Precedence: bulk List-ID: X-Mailing-List: linux-pci@vger.kernel.org On Tue, Jan 19, 2021 at 3:32 PM Greg Kroah-Hartman wrote: > > On Tue, Jan 19, 2021 at 09:17:55AM +0100, Daniel Vetter wrote: > > On Fri, Nov 27, 2020 at 5:42 PM 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. > > > > > > 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. The cleanest way i= s > > > to adjust this at at ->open time: > > > > > > - for sysfs this is easy, now that binary attributes support this. We > > > just set bin_attr->mapping when mmap is supported > > > - for procfs it's a bit more tricky, since procfs pci access has only > > > one file per device, and access to a specific resources first needs > > > to be set up with some ioctl calls. But mmap is only supported for > > > the same resources as sysfs exposes with mmap support, and otherwis= e > > > rejected, so we can set the mapping unconditionally at open time > > > without harm. > > > > > > A special consideration is for arch_can_pci_mmap_io() - we need to > > > make sure that the ->f_mapping doesn't alias between ioport and iomem > > > space. There's only 2 ways in-tree to support mmap of ioports: generi= c > > > pci mmap (ARCH_GENERIC_PCI_MMAP_RESOURCE), and sparc as the single > > > architecture hand-rolling. Both approach support ioport mmap through = a > > > special pfn range and not through magic pte attributes. Aliasing is > > > therefore not a problem. > > > > > > The only difference in access checks left is that sysfs PCI mmap does > > > not check for CAP_RAWIO. I'm not really sure whether that should be > > > added or not. > > > > > > Acked-by: Bjorn Helgaas > > > Reviewed-by: Dan Williams > > > Signed-off-by: Daniel Vetter > > > Cc: Jason Gunthorpe > > > Cc: Kees Cook > > > Cc: Dan Williams > > > Cc: Andrew Morton > > > Cc: John Hubbard > > > Cc: J=C3=A9r=C3=B4me Glisse > > > Cc: Jan Kara > > > Cc: Dan Williams > > > Cc: Greg Kroah-Hartman > > > Cc: linux-mm@kvack.org > > > Cc: linux-arm-kernel@lists.infradead.org > > > Cc: linux-samsung-soc@vger.kernel.org > > > Cc: linux-media@vger.kernel.org > > > Cc: Bjorn Helgaas > > > Cc: linux-pci@vger.kernel.org > > > Signed-off-by: Daniel Vetter > > > -- > > > v2: > > > - Totally new approach: Adjust filp->f_mapping at open time. Note tha= t > > > this now works on all architectures, not just those support > > > ARCH_GENERIC_PCI_MMAP_RESOURCE > > > --- > > > drivers/pci/pci-sysfs.c | 4 ++++ > > > drivers/pci/proc.c | 1 + > > > 2 files changed, 5 insertions(+) > > > > > > diff --git a/drivers/pci/pci-sysfs.c b/drivers/pci/pci-sysfs.c > > > index d15c881e2e7e..3f1c31bc0b7c 100644 > > > --- a/drivers/pci/pci-sysfs.c > > > +++ b/drivers/pci/pci-sysfs.c > > > @@ -929,6 +929,7 @@ void pci_create_legacy_files(struct pci_bus *b) > > > b->legacy_io->read =3D pci_read_legacy_io; > > > b->legacy_io->write =3D pci_write_legacy_io; > > > b->legacy_io->mmap =3D pci_mmap_legacy_io; > > > + b->legacy_io->mapping =3D iomem_get_mapping(); > > > pci_adjust_legacy_attr(b, pci_mmap_io); > > > error =3D device_create_bin_file(&b->dev, b->legacy_io); > > > if (error) > > > @@ -941,6 +942,7 @@ void pci_create_legacy_files(struct pci_bus *b) > > > b->legacy_mem->size =3D 1024*1024; > > > b->legacy_mem->attr.mode =3D 0600; > > > b->legacy_mem->mmap =3D pci_mmap_legacy_mem; > > > + b->legacy_io->mapping =3D iomem_get_mapping(); > > > > Unlike the normal pci stuff below, the legacy files here go boom > > because they're set up much earlier in the boot sequence. This only > > affects HAVE_PCI_LEGACY architectures, which aren't that many. So what > > should we do here now: > > - drop the devmem revoke for these > > - rework the init sequence somehow to set up these files a lot later > > - redo the sysfs patch so that it doesn't take an address_space > > pointer, but instead a callback to get at that (since at open time > > everything is set up). Imo rather ugly > > - ditch this part of the series (since there's not really any takers > > for the latter parts it might just not make sense to push for this) > > - something else? > > > > Bjorn, Greg, thoughts? > > What sysfs patch are you referring to here? Currently in linux-next: commit 74b30195395c406c787280a77ae55aed82dbbfc7 (HEAD -> topic/iomem-mmap-vs-gup, drm/topic/iomem-mmap-vs-gup) Author: Daniel Vetter Date: Fri Nov 27 17:41:25 2020 +0100 sysfs: Support zapping of binary attr mmaps Or the patch right before this one in this submission here: https://lore.kernel.org/dri-devel/20201127164131.2244124-12-daniel.vetter@f= fwll.ch/ Cheers, Daniel --=20 Daniel Vetter Software Engineer, Intel Corporation http://blog.ffwll.ch