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 7F20BC433E0 for ; Tue, 19 Jan 2021 08:19:35 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 2742B2311C for ; Tue, 19 Jan 2021 08:19:35 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729488AbhASIT2 (ORCPT ); Tue, 19 Jan 2021 03:19:28 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:57726 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726601AbhASITU (ORCPT ); Tue, 19 Jan 2021 03:19:20 -0500 Received: from mail-ot1-x335.google.com (mail-ot1-x335.google.com [IPv6:2607:f8b0:4864:20::335]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 57385C0613D3 for ; Tue, 19 Jan 2021 00:18:07 -0800 (PST) Received: by mail-ot1-x335.google.com with SMTP id o11so19009791ote.4 for ; Tue, 19 Jan 2021 00:18:07 -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=WfFJuLm0JWFKIZSr35gVwj0xg2AYZzNEcuLqFUXW2+8=; b=PbkKRo7SNg95R94SiZevOw2BEtiFlTjvdHUYcZPMAnSrGIckYOkeHga/KY6+b/RNEu RQKckLdL5MSMzGFd7lJcRzJqnGxbYjtG1EOrlYplFzb90mxOoz3o6SCb0Xws/78s2/JW OCW0F7fS42A6taX0chOn4gczjDBvyZIQbF25k= 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=WfFJuLm0JWFKIZSr35gVwj0xg2AYZzNEcuLqFUXW2+8=; b=uOSqMGLQwtCSczJ3hhaKTqIuz2RCYZxuxyh9FhwJBFxR+5GytTNOLEMroZyzI84Fbj Le0QBGX2njH5Oe6K3/RSxmd1TvBtm8YcUzU3X/fTZialbQCkNdpkAldmQY6YmsH+9tgN UUD3yXE9BoG43Zn1XvhjSgs0zu3AJLzuAlProzeR4x1eWrMRtaVt72+cDOXmY1pljmck W2QH8nOQ5/9OaBxZXJyyqf6Dlog1HdRWlXhcsYa1SOAsVf4vWq4Aiuzab8woeijkN57z 4GSa/GI9DI2xq12DoK2AHTmbFRiksSkQ4HhewZp7g3Ak5067XJNZuwmuv3Yx2PJBcltN G3aA== X-Gm-Message-State: AOAM532j+jTNSa0C4ocXA9RsuK7zMVPPrOq83CF2S3C5UhlYDNJiDUM3 SZVVzxkiVkTYx2TcRJsVQx/Css5GAaVDIL77SUksoA== X-Google-Smtp-Source: ABdhPJzaeODA4sJQGtFnmlEJhEIejHm5tUfJ6WBUJaaM4JSKW7UsD8q5H1JPOzhq7vW/xPspCH7j/ySdSzg97qcaAUI= X-Received: by 2002:a9d:23ca:: with SMTP id t68mr2659337otb.281.1611044286607; Tue, 19 Jan 2021 00:18:06 -0800 (PST) MIME-Version: 1.0 References: <20201127164131.2244124-1-daniel.vetter@ffwll.ch> <20201127164131.2244124-13-daniel.vetter@ffwll.ch> In-Reply-To: <20201127164131.2244124-13-daniel.vetter@ffwll.ch> From: Daniel Vetter Date: Tue, 19 Jan 2021 09:17:55 +0100 Message-ID: Subject: Re: [PATCH v7 12/17] PCI: Revoke mappings like devmem To: DRI Development , LKML , Stephen Rothwell Cc: 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 , Greg Kroah-Hartman , 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 Fri, Nov 27, 2020 at 5:42 PM Daniel Vetter wrot= e: > > 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. > > 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 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 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? Issuge got reported by Stephen on a powerpc when trying to build linux-next with this patch included. Thanks, Daniel > 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, in= t 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, str= uct file *file) > fpriv->write_combine =3D 0; > > file->private_data =3D fpriv; > + file->f_mapping =3D iomem_get_mapping(); > > return 0; > } > -- > 2.29.2 > --=20 Daniel Vetter Software Engineer, Intel Corporation http://blog.ffwll.ch