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=-10.1 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,INCLUDES_PATCH,MAILING_LIST_MULTI, SIGNED_OFF_BY,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 D7353C55178 for ; Tue, 3 Nov 2020 21:30:57 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id A583C22404 for ; Tue, 3 Nov 2020 21:30:57 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1604439057; bh=gFAgHCJWNmyQv8XlwrCh9kp3qGCPYDz+IyZljoQ6Ups=; h=Date:From:To:Cc:Subject:In-Reply-To:List-ID:From; b=PjbWEhkYDRyBGVQ9mJoaPwGRCZYauzwNwT39j6VSNo7GoIjmHbbgDsiDReNSTvhFA 4otiV6CIiPOfXB4eu2dnZy2gaDFk1FOPsy6Sq7O0NIJziBHM5rjyG+5hYQC0mzyezV dPfh7ufQjUrtVXerJx30frU9gU34vvJyx2H91gJM= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1732408AbgKCVaw (ORCPT ); Tue, 3 Nov 2020 16:30:52 -0500 Received: from mail.kernel.org ([198.145.29.99]:49892 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1731546AbgKCVau (ORCPT ); Tue, 3 Nov 2020 16:30:50 -0500 Received: from localhost (230.sub-72-107-127.myvzw.com [72.107.127.230]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 44A0721534; Tue, 3 Nov 2020 21:30:49 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1604439049; bh=gFAgHCJWNmyQv8XlwrCh9kp3qGCPYDz+IyZljoQ6Ups=; h=Date:From:To:Cc:Subject:In-Reply-To:From; b=HPIF3XrIciMDdSu7IGKOJ2VjSvbDSacEXORbsIuVGj6fyf3x9OQrRmMY+UbQhcHod S0PweedIfoil4rWheiyrbxThkEJx6xR3EmK7UER4Lwppn2I8mdb/JZGIaxfx9sH5wo Y1sD3IWMwbGA0osqLFzmB0xss30QQlrpQVsT0BXs= Date: Tue, 3 Nov 2020 15:30:47 -0600 From: Bjorn Helgaas To: Daniel Vetter Cc: DRI Development , LKML , kvm@vger.kernel.org, linux-mm@kvack.org, linux-arm-kernel@lists.infradead.org, linux-samsung-soc@vger.kernel.org, linux-media@vger.kernel.org, Daniel Vetter , Jason Gunthorpe , Kees Cook , Dan Williams , Andrew Morton , John Hubbard , =?iso-8859-1?B?Suly9G1l?= Glisse , Jan Kara , Greg Kroah-Hartman , Bjorn Helgaas , linux-pci@vger.kernel.org Subject: Re: [PATCH v5 15/15] PCI: Revoke mappings like devmem Message-ID: <20201103213047.GA267004@bjorn-Precision-5520> MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <20201030100815.2269-16-daniel.vetter@ffwll.ch> Precedence: bulk List-ID: X-Mailing-List: linux-samsung-soc@vger.kernel.org On Fri, Oct 30, 2020 at 11:08:15AM +0100, 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 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 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 otherwise > 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: generic > 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. > > Signed-off-by: Daniel Vetter > Cc: Jason Gunthorpe > Cc: Kees Cook > Cc: Dan Williams > Cc: Andrew Morton > Cc: John Hubbard > Cc: Jérôme 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 Acked-by: Bjorn Helgaas > -- > 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 = pci_read_legacy_io; > b->legacy_io->write = pci_write_legacy_io; > b->legacy_io->mmap = pci_mmap_legacy_io; > + b->legacy_io->mapping = iomem_get_mapping(); > pci_adjust_legacy_attr(b, pci_mmap_io); > error = 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 = 1024*1024; > b->legacy_mem->attr.mode = 0600; > b->legacy_mem->mmap = pci_mmap_legacy_mem; > + b->legacy_io->mapping = iomem_get_mapping(); > pci_adjust_legacy_attr(b, pci_mmap_mem); > error = device_create_bin_file(&b->dev, b->legacy_mem); > if (error) > @@ -1156,6 +1158,8 @@ static int pci_create_attr(struct pci_dev *pdev, int num, int write_combine) > res_attr->mmap = pci_mmap_resource_uc; > } > } > + if (res_attr->mmap) > + res_attr->mapping = iomem_get_mapping(); > res_attr->attr.name = res_attr_name; > res_attr->attr.mode = 0600; > res_attr->size = pci_resource_len(pdev, num); > diff --git a/drivers/pci/proc.c b/drivers/pci/proc.c > index 3a2f90beb4cb..9bab07302bbf 100644 > --- a/drivers/pci/proc.c > +++ b/drivers/pci/proc.c > @@ -298,6 +298,7 @@ static int proc_bus_pci_open(struct inode *inode, struct file *file) > fpriv->write_combine = 0; > > file->private_data = fpriv; > + file->f_mapping = iomem_get_mapping(); > > return 0; > } > -- > 2.28.0 >