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_BLOCKED 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 467BEC433E9 for ; Wed, 3 Feb 2021 16:16:12 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id F3DBC64E31 for ; Wed, 3 Feb 2021 16:16:11 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S235015AbhBCQPx (ORCPT ); Wed, 3 Feb 2021 11:15:53 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:49900 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S234773AbhBCQPV (ORCPT ); Wed, 3 Feb 2021 11:15:21 -0500 Received: from mail-oi1-x231.google.com (mail-oi1-x231.google.com [IPv6:2607:f8b0:4864:20::231]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id C0FC3C061573 for ; Wed, 3 Feb 2021 08:14:40 -0800 (PST) Received: by mail-oi1-x231.google.com with SMTP id k142so397359oib.7 for ; Wed, 03 Feb 2021 08:14:40 -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=bCfZ/a/6NOr6nE7maD0+c3yfEPShyNSVY7EhDvteykY=; b=F30Nrt9vPiAB/zyqMpbpGMCX5+9GbissyHIBmWRmyMfHwYjqRyqHPvGGNSQswndDl8 ueuYjPhiYQRYrUuuoE2fCSgdN6wSgEVa4WV8ZAaC0Pdwh0MqPavWRi9wHjisevfaVscM tKXh1rpbVgrfZgdHoSxmfIAY/17F42+Ith6ME= 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=bCfZ/a/6NOr6nE7maD0+c3yfEPShyNSVY7EhDvteykY=; b=pZWicmGXDXaXfLQ2YAmTUgmg7N/yrVeYlAfZaku3GuAfoJnfvyOwtKdX/oArDE8QuW f6wdICv2UD/ntCIeKptAv4ywH6ry4AiYEZoQvys8C0knA5KmMwrDYBp4HXUjiQA3u24h wSzIwjbyNXOWVsPr7w5X1oeN47DbfuqfYoywYCfhzbFXjYPXOwmtjOnjAjmBZjon7QWM O3L0U0KmtBtgoZLRA1C/P6umNUeT6Z3svOC7ruyej8sZ60MCwYPcdTUKuC/9Z+z9klnJ aegK/+L/f65Mlr5n5CxwbjyrHdyT9tV120GNlDOd11+kaNymTn7Afv0u9/I6BrnY6fQz cKTA== X-Gm-Message-State: AOAM531eNq1N5jOqV8Cjbt9w/TlV1p8BDsWXx9y6HmDL4+UzrF/QO4/m SUbB5DPVbXrG/g7KrYLjTbPsudqn0b8coohsujBO+A== X-Google-Smtp-Source: ABdhPJxC2Hr09yAlU46Rq8Zw9mzo14g2j/8RncSJTzh5gFRD/Uq7tpWlsM64N23HZFbUWxoY/ZCynmvy0uA3EPvqdek= X-Received: by 2002:aca:1906:: with SMTP id l6mr2422037oii.101.1612368880228; Wed, 03 Feb 2021 08:14:40 -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: Wed, 3 Feb 2021 17:14:29 +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: kvm@vger.kernel.org On Tue, Jan 19, 2021 at 5:03 PM Daniel Vetter wrot= e: > > On Tue, Jan 19, 2021 at 4:20 PM Greg Kroah-Hartman > wrote: > > > > On Tue, Jan 19, 2021 at 03:34:47PM +0100, Daniel Vetter wrote: > > > 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 cl= aims > > > > > > the region") /dev/kmem zaps ptes when the kernel requests exclu= sive > > > > > > acccess to an iomem region. And with CONFIG_IO_STRICT_DEVMEM, t= his 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 sa= me > > > > > > address_space, with consistent vma->vm_pgoff. ->pgoff is alread= y > > > > > > adjusted, because that's how (io_)remap_pfn_range works, but fo= r the > > > > > > mapping we need to adjust vma->vm_file->f_mapping. The cleanest= way is > > > > > > to adjust this at at ->open time: > > > > > > > > > > > > - for sysfs this is easy, now that binary attributes support th= is. We > > > > > > just set bin_attr->mapping when mmap is supported > > > > > > - for procfs it's a bit more tricky, since procfs pci access ha= s 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 supporte= d for > > > > > > the same resources as sysfs exposes with mmap support, and ot= herwise > > > > > > rejected, so we can set the mapping unconditionally at open t= ime > > > > > > 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: = generic > > > > > > pci mmap (ARCH_GENERIC_PCI_MMAP_RESOURCE), and sparc as the sin= gle > > > > > > architecture hand-rolling. Both approach support ioport mmap th= rough a > > > > > > special pfn range and not through magic pte attributes. Aliasin= g is > > > > > > therefore not a problem. > > > > > > > > > > > > The only difference in access checks left is that sysfs PCI mma= p does > > > > > > not check for CAP_RAWIO. I'm not really sure whether that shoul= d 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. No= te that > > > > > > 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 on= ly > > > > > 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 la= ter > > > > > - 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 tim= e > > > > > everything is set up). Imo rather ugly > > > > > - ditch this part of the series (since there's not really any tak= ers > > > > > for the latter parts it might just not make sense to push for thi= s) > > > > > - 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.ve= tter@ffwll.ch/ > > > > Ah. Hm, a callback in the sysfs file logic seems really hairy, so I > > would prefer that not happen. If no one really needs this stuff, why > > not just drop it like you mention? > > Well it is needed, but just on architectures I don't care about much. > Most relevant is perhaps powerpc (that's where Stephen hit the issue). > I do wonder whether we could move the legacy pci files setup to where > the modern stuff is set up from pci_create_resource_files() or maybe > pci_create_sysfs_dev_files() even for HAVE_PCI_LEGACY. I think that > might work, but since it's legacy flow on some funny architectures > (alpha, itanium, that kind of stuff) I have no idea what kind of > monsters I'm going to anger :-) Back from a week of vacation, I looked at this again and I think shouldn't be hard to fix this with the sam trick pci_create_sysfs_dev_files() uses: As long as sysfs_initialized isn't set we skip, and then later on when the vfs is up&running we can initialize everything. To be able to apply the same thing to pci_create_legacy_files() I think all I need is to iterate overa all struct pci_bus in pci_sysfs_init() and we're good. Unfortunately I didn't find any for_each_pci_bus(), so how do I do that? Thanks, Daniel --=20 Daniel Vetter Software Engineer, Intel Corporation http://blog.ffwll.ch