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=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 EC0B3C43381 for ; Tue, 19 Jan 2021 14:35:01 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id 741242072C for ; Tue, 19 Jan 2021 14:35:01 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 741242072C Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=ffwll.ch Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=owner-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix) id B990D8D002E; Tue, 19 Jan 2021 09:35:00 -0500 (EST) Received: by kanga.kvack.org (Postfix, from userid 40) id B48206B00D5; Tue, 19 Jan 2021 09:35:00 -0500 (EST) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id A37048D002E; Tue, 19 Jan 2021 09:35:00 -0500 (EST) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0245.hostedemail.com [216.40.44.245]) by kanga.kvack.org (Postfix) with ESMTP id 8A8EC6B00C2 for ; Tue, 19 Jan 2021 09:35:00 -0500 (EST) Received: from smtpin25.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay01.hostedemail.com (Postfix) with ESMTP id 57FF1180AD83B for ; Tue, 19 Jan 2021 14:35:00 +0000 (UTC) X-FDA: 77722771560.25.baby54_0e05a4727552 Received: from filter.hostedemail.com (10.5.16.251.rfc1918.com [10.5.16.251]) by smtpin25.hostedemail.com (Postfix) with ESMTP id 3E5CD1804E3AD for ; Tue, 19 Jan 2021 14:35:00 +0000 (UTC) X-HE-Tag: baby54_0e05a4727552 X-Filterd-Recvd-Size: 9097 Received: from mail-ot1-f50.google.com (mail-ot1-f50.google.com [209.85.210.50]) by imf47.hostedemail.com (Postfix) with ESMTP for ; Tue, 19 Jan 2021 14:34:59 +0000 (UTC) Received: by mail-ot1-f50.google.com with SMTP id 34so9112146otd.5 for ; Tue, 19 Jan 2021 06:34:58 -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=4e0CGYDHUfu279fyABP5Y+REbie5VpiNs9f4Knw2Cok=; b=VBqn8DUOGeynSeRg3k1zvnxZgxHVN/m4CmDY5MHMndd1hrRsvbsOlsUR+N5zIlZNjv I1JtDyXv8bu7TYIBeBou0qbqzOTX9l2l0clQMWnlaS5BEAD0UdAQ7SGwdm49iZ4AHegS P3+zFz0CEInVbSD6li/gqZsMR+ZONkqJPxGNc= 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=4e0CGYDHUfu279fyABP5Y+REbie5VpiNs9f4Knw2Cok=; b=cXaAEr+PKmp9z6P3t6zQOLEdAZl5f+o2JBsbZArmo2QqCxuK7VOGHrUaOf6l2DT+gH JjdKwrv4Rds49jwbKenF8emSzcJPESYdATakl2B8GVzsd0T9nMVRpmRmVNUAybMOVikI s8D1tJrP7IlH6UvOyR+KGwcAk/1tPgPjXnOL6cRboH6MVCxf+zGzPyrJChRjsGQDhCL9 ChNFb1QoWkqfESg06bQMMj5OIOA4LkdCcebcI8CEPODGpCORtYPbzrrtRt2jjzLL4r/N wI+4Gq1j2Ev7UAR8QnsVSCKHHCz5tqi/UASheOW4jPYTyFuRTPTe/9eWbFHAtLLtwKah 8Y1w== X-Gm-Message-State: AOAM533jG8HmhsPLbtsylWciafEu7GpX+hipafA1b83MS+5k9CskXvs3 tJ5kjvTD26mTY2+9shGqvQD3k8Edyz3ylp+fjSvPKQ== X-Google-Smtp-Source: ABdhPJxNAs6mhMviXMtFn7M206VEX/Eake/mU9seAOwtJ76LA2Emqx8YbNqRC8ThlQu1JNtpKUawwkeGr99A8LNHJEY= X-Received: by 2002:a9d:ea6:: with SMTP id 35mr3626432otj.188.1611066898227; Tue, 19 Jan 2021 06:34:58 -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: Tue, 19 Jan 2021 15:34:47 +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 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 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 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 i= s > > > 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 otherwis= e > > > 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: generi= c > > > 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 tha= t > > > 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? > > 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.vetter@f= fwll.ch/ Cheers, Daniel --=20 Daniel Vetter Software Engineer, Intel Corporation http://blog.ffwll.ch