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=-9.8 required=3.0 tests=BAYES_00,DKIM_INVALID, DKIM_SIGNED,INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE, SPF_PASS,URIBL_BLOCKED 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 1A879C388F7 for ; Tue, 3 Nov 2020 21:30:53 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id 946C2223C7 for ; Tue, 3 Nov 2020 21:30:52 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=fail reason="signature verification failed" (1024-bit key) header.d=kernel.org header.i=@kernel.org header.b="HPIF3XrI" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 946C2223C7 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=kernel.org Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=owner-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix) id 2BA436B0068; Tue, 3 Nov 2020 16:30:52 -0500 (EST) Received: by kanga.kvack.org (Postfix, from userid 40) id 2430F6B006C; Tue, 3 Nov 2020 16:30:52 -0500 (EST) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 0E4EF6B006E; Tue, 3 Nov 2020 16:30:52 -0500 (EST) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0201.hostedemail.com [216.40.44.201]) by kanga.kvack.org (Postfix) with ESMTP id BC4236B0068 for ; Tue, 3 Nov 2020 16:30:51 -0500 (EST) Received: from smtpin02.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay02.hostedemail.com (Postfix) with ESMTP id 606553625 for ; Tue, 3 Nov 2020 21:30:51 +0000 (UTC) X-FDA: 77444401902.02.stone87_2f0f67e272bb Received: from filter.hostedemail.com (10.5.16.251.rfc1918.com [10.5.16.251]) by smtpin02.hostedemail.com (Postfix) with ESMTP id 3CB8210097AA2 for ; Tue, 3 Nov 2020 21:30:51 +0000 (UTC) X-HE-Tag: stone87_2f0f67e272bb X-Filterd-Recvd-Size: 6633 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by imf09.hostedemail.com (Postfix) with ESMTP for ; Tue, 3 Nov 2020 21:30:50 +0000 (UTC) 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 In-Reply-To: <20201030100815.2269-16-daniel.vetter@ffwll.ch> 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 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. >=20 > Except there's two more ways to access PCI BARs: sysfs and proc mmap > support. Let's plug that hole. >=20 > 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: >=20 > - 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. >=20 > 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. >=20 > 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. >=20 > 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 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(+) >=20 > 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(); > pci_adjust_legacy_attr(b, pci_mmap_mem); > error =3D 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 =3D pci_mmap_resource_uc; > } > } > + if (res_attr->mmap) > + res_attr->mapping =3D iomem_get_mapping(); > res_attr->attr.name =3D res_attr_name; > res_attr->attr.mode =3D 0600; > res_attr->size =3D 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, s= truct file *file) > fpriv->write_combine =3D 0; > =20 > file->private_data =3D fpriv; > + file->f_mapping =3D iomem_get_mapping(); > =20 > return 0; > } > --=20 > 2.28.0 >=20