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=-13.6 required=3.0 tests=BAYES_00,DKIM_INVALID, DKIM_SIGNED,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,URIBL_RED autolearn=ham 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 802D7C433E0 for ; Tue, 19 Jan 2021 15:20:48 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id F0E5A22D2A for ; Tue, 19 Jan 2021 15:20:47 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org F0E5A22D2A Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=linuxfoundation.org Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=owner-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix) id 0F4C86B0006; Tue, 19 Jan 2021 10:20:47 -0500 (EST) Received: by kanga.kvack.org (Postfix, from userid 40) id 0A5146B0007; Tue, 19 Jan 2021 10:20:47 -0500 (EST) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id EB09E6B0008; Tue, 19 Jan 2021 10:20:46 -0500 (EST) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0110.hostedemail.com [216.40.44.110]) by kanga.kvack.org (Postfix) with ESMTP id D50396B0006 for ; Tue, 19 Jan 2021 10:20:46 -0500 (EST) Received: from smtpin03.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay02.hostedemail.com (Postfix) with ESMTP id F07EC3628 for ; Tue, 19 Jan 2021 15:20:45 +0000 (UTC) X-FDA: 77722886892.03.cup80_620136a27552 Received: from filter.hostedemail.com (10.5.16.251.rfc1918.com [10.5.16.251]) by smtpin03.hostedemail.com (Postfix) with ESMTP id C601E28A4E8 for ; Tue, 19 Jan 2021 15:20:45 +0000 (UTC) X-HE-Tag: cup80_620136a27552 X-Filterd-Recvd-Size: 8352 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by imf05.hostedemail.com (Postfix) with ESMTP for ; Tue, 19 Jan 2021 15:20:45 +0000 (UTC) Received: by mail.kernel.org (Postfix) with ESMTPSA id 01D6B23110; Tue, 19 Jan 2021 15:20:42 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1611069643; bh=yf0s5Hnc71ZDmBnzFPUIWJfODcCah0cMw3TOXpxitO8=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=OPWVYTJT0MTCcxZuwblNq7+3b1gj+nFAHJTjvYu2HvxCc6I0hXTJ1f99Hx6kObw9S 3T2zTE+1KLE5UAjzDJOua6M3j09lPQu2AAaG1L6v07ro43OEJU5gr+mMkZZEm9L8xP K02wA0GlOA5PZ2VRAsLSociEkRhvBkyr0kwkafUk= Date: Tue, 19 Jan 2021 16:20:40 +0100 From: Greg Kroah-Hartman To: Daniel Vetter 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 , =?iso-8859-1?B?Suly9G1l?= Glisse , Jan Kara , Linux PCI Subject: Re: [PATCH v7 12/17] PCI: Revoke mappings like devmem Message-ID: References: <20201127164131.2244124-1-daniel.vetter@ffwll.ch> <20201127164131.2244124-13-daniel.vetter@ffwll.ch> MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Disposition: inline In-Reply-To: Content-Transfer-Encoding: quoted-printable 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 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 clai= ms > > > > the region") /dev/kmem zaps ptes when the kernel requests exclusi= ve > > > > acccess to an iomem region. And with CONFIG_IO_STRICT_DEVMEM, thi= s is > > > > the default for all driver uses. > > > > > > > > Except there's two more ways to access PCI BARs: sysfs and proc m= map > > > > 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 w= ay is > > > > 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 n= eeds > > > > to be set up with some ioctl calls. But mmap is only supported = for > > > > the same resources as sysfs exposes with mmap support, and othe= rwise > > > > rejected, so we can set the mapping unconditionally at open tim= e > > > > without harm. > > > > > > > > A special consideration is for arch_can_pci_mmap_io() - we need t= o > > > > make sure that the ->f_mapping doesn't alias between ioport and i= omem > > > > space. There's only 2 ways in-tree to support mmap of ioports: ge= neric > > > > pci mmap (ARCH_GENERIC_PCI_MMAP_RESOURCE), and sparc as the singl= e > > > > architecture hand-rolling. Both approach support ioport mmap thro= ugh 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=E9r=F4me 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= 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 only > > > affects HAVE_PCI_LEGACY architectures, which aren't that many. So w= hat > > > should we do here now: > > > - drop the devmem revoke for these > > > - rework the init sequence somehow to set up these files a lot late= r > > > - 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 taker= s > > > 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? >=20 > Currently in linux-next: >=20 > 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 >=20 > sysfs: Support zapping of binary attr mmaps >=20 > Or the patch right before this one in this submission here: >=20 > https://lore.kernel.org/dri-devel/20201127164131.2244124-12-daniel.vett= er@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? thanks, greg k-h