From: Daniel Vetter <daniel.vetter@ffwll.ch>
To: Bjorn Helgaas <helgaas@kernel.org>
Cc: linux-s390@vger.kernel.org,
linux-samsung-soc <linux-samsung-soc@vger.kernel.org>,
"Jan Kara" <jack@suse.cz>, "Kees Cook" <keescook@chromium.org>,
kvm@vger.kernel.org, "Jason Gunthorpe" <jgg@ziepe.ca>,
"John Hubbard" <jhubbard@nvidia.com>,
LKML <linux-kernel@vger.kernel.org>,
"DRI Development" <dri-devel@lists.freedesktop.org>,
"Linux MM" <linux-mm@kvack.org>,
"Jérôme Glisse" <jglisse@redhat.com>,
"Linux PCI" <linux-pci@vger.kernel.org>,
"Bjorn Helgaas" <bhelgaas@google.com>,
"Daniel Vetter" <daniel.vetter@intel.com>,
"Dan Williams" <dan.j.williams@intel.com>,
"Andrew Morton" <akpm@linux-foundation.org>,
"Linux ARM" <linux-arm-kernel@lists.infradead.org>,
"open list:DMA BUFFER SHARING FRAMEWORK"
<linux-media@vger.kernel.org>
Subject: Re: [PATCH 10/13] PCI: revoke mappings like devmem
Date: Wed, 7 Oct 2020 21:24:49 +0200 [thread overview]
Message-ID: <CAKMK7uEi-PaoP2mSgg-aub49gctjTbwW6-X4nuRLnv1uzTh9dQ@mail.gmail.com> (raw)
In-Reply-To: <20201007184131.GA3259154@bjorn-Precision-5520>
On Wed, Oct 7, 2020 at 8:41 PM Bjorn Helgaas <helgaas@kernel.org> wrote:
>
> Capitalize subject, like other patches in this series and previous
> drivers/pci history.
>
> On Wed, Oct 07, 2020 at 06:44:23PM +0200, 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.
>
> s/pci/PCI/ in commit logs and comments.
>
> > 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. Usually that's done
> > at ->open time, but that's a bit tricky here with all the entry points
> > and arch code. So instead create a fake file and adjust vma->vm_file.
> >
> > Note this only works for ARCH_GENERIC_PCI_MMAP_RESOURCE. But that
> > seems to be a subset of architectures support STRICT_DEVMEM, so we
> > should be good.
> >
> > The only difference in access checks left is that sysfs pci mmap does
> > not check for CAP_RAWIO. But I think that makes some sense compared to
> > /dev/mem and proc, where one file gives you access to everything and
> > no ownership applies.
>
> > --- a/drivers/char/mem.c
> > +++ b/drivers/char/mem.c
> > @@ -810,6 +810,7 @@ static loff_t memory_lseek(struct file *file, loff_t offset, int orig)
> > }
> >
> > static struct inode *devmem_inode;
> > +static struct vfsmount *devmem_vfs_mount;
> >
> > #ifdef CONFIG_IO_STRICT_DEVMEM
> > void revoke_devmem(struct resource *res)
> > @@ -843,6 +844,20 @@ void revoke_devmem(struct resource *res)
> >
> > unmap_mapping_range(inode->i_mapping, res->start, resource_size(res), 1);
> > }
> > +
> > +struct file *devmem_getfile(void)
> > +{
> > + struct file *file;
> > +
> > + file = alloc_file_pseudo(devmem_inode, devmem_vfs_mount, "devmem",
> > + O_RDWR, &kmem_fops);
> > + if (IS_ERR(file))
> > + return NULL;
> > +
> > + file->f_mapping = devmem_indoe->i_mapping;
>
> "devmem_indoe"? Obviously not compiled, I guess?
Yeah apologies, I forgot to compile this with CONFIG_IO_STRICT_DEVMEM
set. The entire series is more rfc about the overall problem really, I
need to also figure out how to even this this somehow. I guess there's
nothing really ready made here?
-Daniel
> > --- a/include/linux/ioport.h
> > +++ b/include/linux/ioport.h
> > @@ -304,8 +304,10 @@ struct resource *request_free_mem_region(struct resource *base,
> >
> > #ifdef CONFIG_IO_STRICT_DEVMEM
> > void revoke_devmem(struct resource *res);
> > +struct file *devm_getfile(void);
> > #else
> > static inline void revoke_devmem(struct resource *res) { };
> > +static inline struct file *devmem_getfile(void) { return NULL; };
>
> I guess these names are supposed to match?
>
> > #endif
> >
> > #endif /* __ASSEMBLY__ */
> > --
> > 2.28.0
> >
--
Daniel Vetter
Software Engineer, Intel Corporation
http://blog.ffwll.ch
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next prev parent reply other threads:[~2020-10-07 19:25 UTC|newest]
Thread overview: 55+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-10-07 16:44 [PATCH 00/13] follow_pfn and other iomap races Daniel Vetter
2020-10-07 16:44 ` [PATCH 01/13] drm/exynos: Stop using frame_vector helpers Daniel Vetter
2020-10-07 20:32 ` John Hubbard
2020-10-07 21:32 ` Daniel Vetter
2020-10-07 21:36 ` John Hubbard
2020-10-07 21:50 ` Daniel Vetter
2020-10-07 16:44 ` [PATCH 02/13] drm/exynos: Use FOLL_LONGTERM for g2d cmdlists Daniel Vetter
2020-10-07 20:43 ` John Hubbard
2020-10-07 16:44 ` [PATCH 03/13] misc/habana: Stop using frame_vector helpers Daniel Vetter
2020-10-07 20:38 ` John Hubbard
2020-10-07 16:44 ` [PATCH 04/13] misc/habana: Use FOLL_LONGTERM for userptr Daniel Vetter
2020-10-07 20:46 ` John Hubbard
2020-10-07 16:44 ` [PATCH 05/13] mm/frame-vector: Use FOLL_LONGTERM Daniel Vetter
2020-10-07 16:53 ` Jason Gunthorpe
2020-10-07 17:12 ` Daniel Vetter
2020-10-07 17:33 ` Jason Gunthorpe
2020-10-07 21:13 ` John Hubbard
2020-10-07 21:30 ` Daniel Vetter
2020-10-07 16:44 ` [PATCH 06/13] media: videobuf2: Move frame_vector into media subsystem Daniel Vetter
2020-10-07 22:18 ` John Hubbard
2020-10-07 16:44 ` [PATCH 07/13] mm: close race in generic_access_phys Daniel Vetter
2020-10-07 17:27 ` Jason Gunthorpe
2020-10-07 18:01 ` Daniel Vetter
2020-10-07 23:21 ` Jason Gunthorpe
2020-10-08 0:44 ` John Hubbard
2020-10-08 7:23 ` Daniel Vetter
2020-10-07 16:44 ` [PATCH 08/13] s390/pci: Remove races against pte updates Daniel Vetter
2020-10-08 16:44 ` Gerald Schaefer
2020-10-08 17:16 ` Daniel Vetter
2020-10-07 16:44 ` [PATCH 09/13] PCI: obey iomem restrictions for procfs mmap Daniel Vetter
2020-10-07 18:46 ` Bjorn Helgaas
2020-10-07 16:44 ` [PATCH 10/13] PCI: revoke mappings like devmem Daniel Vetter
2020-10-07 18:41 ` Bjorn Helgaas
2020-10-07 19:24 ` Daniel Vetter [this message]
2020-10-07 19:33 ` Dan Williams
2020-10-07 19:47 ` Daniel Vetter
2020-10-07 22:23 ` Dan Williams
2020-10-07 22:29 ` Dan Williams
2020-10-08 8:09 ` Daniel Vetter
2020-10-07 23:24 ` Jason Gunthorpe
2020-10-08 7:31 ` Daniel Vetter
2020-10-08 7:49 ` Dan Williams
2020-10-08 8:13 ` Daniel Vetter
2020-10-08 8:35 ` Dan Williams
2020-10-08 12:41 ` Jason Gunthorpe
2020-10-07 16:44 ` [PATCH 11/13] mm: add unsafe_follow_pfn Daniel Vetter
2020-10-07 17:36 ` Jason Gunthorpe
2020-10-07 18:10 ` Daniel Vetter
2020-10-07 19:00 ` Jason Gunthorpe
2020-10-07 19:38 ` Daniel Vetter
2020-10-07 16:44 ` [PATCH 12/13] media/videbuf1|2: Mark follow_pfn usage as unsafe Daniel Vetter
2020-10-07 16:44 ` [PATCH 13/13] vfio/type1: Mark follow_pfn " Daniel Vetter
2020-10-07 17:39 ` Jason Gunthorpe
2020-10-07 18:14 ` Daniel Vetter
2020-10-07 18:47 ` Jason Gunthorpe
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