Re: [PATCH v7 00/17] follow_pfn and other iomap races

Daniel Vetter
2021-01-12T13:29:58Z

On Tue, Jan 12, 2021 at 2:24 PM Daniel Vetter <daniel@ffwll.ch> wrote:
>
> On Fri, Nov 27, 2020 at 05:41:14PM +0100, Daniel Vetter wrote:
> > Hi all
> >
> > Another update of my patch series to clamp down a bunch of races and gaps
> > around follow_pfn and other access to iomem mmaps. Previous version:
> >
> > v1: https://lore.kernel.org/dri-devel/20201007164426.1812530-1-daniel.vetter@ffwll.ch/
> > v2: https://lore.kernel.org/dri-devel/20201009075934.3509076-1-daniel.vetter@ffwll.ch
> > v3: https://lore.kernel.org/dri-devel/20201021085655.1192025-1-daniel.vetter@ffwll.ch/
> > v4: https://lore.kernel.org/dri-devel/20201026105818.2585306-1-daniel.vetter@ffwll.ch/
> > v5: https://lore.kernel.org/dri-devel/20201030100815.2269-1-daniel.vetter@ffwll.ch/
> > v6: https://lore.kernel.org/dri-devel/20201119144146.1045202-1-daniel.vetter@ffwll.ch/
> >
> > And the discussion that sparked this journey:
> >
> > https://lore.kernel.org/dri-devel/20201007164426.1812530-1-daniel.vetter@ffwll.ch/
> >
> > I think the first 12 patches are ready for landing. The parts starting
> > with "mm: Add unsafe_follow_pfn" probably need more baking time.
> >
> > Andrew, can you please pick these up, or do you prefer I do a topic branch
> > and send them to Linus directly in the next merge window?
> >
> > Changes in v7:
> > - more acks/reviews
> > - reordered with the ready pieces at the front
> > - simplified the new follow_pfn function as Jason suggested
> >
> > Changes in v6:
> > - Tested v4l userptr as Tomasz suggested. No boom observed
> > - Added RFC for locking down follow_pfn, per discussion with Christoph and
> > Jason.
> > - Explain why pup_fast is safe in relevant patches, there was a bit a
> > confusion when discussing v5.
> > - Fix up the resource patch, with CONFIG_IO_STRICT_DEVMEM it crashed on
> > boot due to an unintended change (reported by John)
> >
> > Changes in v5:
> > - Tomasz found some issues in the media patches
> > - Polish suggested by Christoph for the unsafe_follow_pfn patch
> >
> > Changes in v4:
> > - Drop the s390 patch, that was very stand-alone and now queued up to land
> > through s390 trees.
> > - Comment polish per Dan's review.
> >
> > Changes in v3:
> > - Bunch of polish all over, no functional changes aside from one barrier
> > in the resource code, for consistency.
> > - A few more r-b tags.
> >
> > Changes in v2:
> > - tons of small polish&fixes all over, thanks to all the reviewers who
> > spotted issues
> > - I managed to test at least the generic_access_phys and pci mmap revoke
> > stuff with a few gdb sessions using our i915 debug tools (hence now also
> > the drm/i915 patch to properly request all the pci bar regions)
> > - reworked approach for the pci mmap revoke: Infrastructure moved into
> > kernel/resource.c, address_space mapping is now set up at open time for
> > everyone (which required some sysfs changes). Does indeed look a lot
> > cleaner and a lot less invasive than I feared at first.
> >
> > Coments and review on the remaining bits very much welcome, especially
> > from the kvm and vfio side.
> >
> > Cheers, Daniel
> >
> > Daniel Vetter (17):
> > drm/exynos: Stop using frame_vector helpers
> > drm/exynos: Use FOLL_LONGTERM for g2d cmdlists
> > misc/habana: Stop using frame_vector helpers
> > misc/habana: Use FOLL_LONGTERM for userptr
> > mm/frame-vector: Use FOLL_LONGTERM
> > media: videobuf2: Move frame_vector into media subsystem
> > mm: Close race in generic_access_phys
> > PCI: Obey iomem restrictions for procfs mmap
> > /dev/mem: Only set filp->f_mapping
> > resource: Move devmem revoke code to resource framework
> > sysfs: Support zapping of binary attr mmaps
> > PCI: Revoke mappings like devmem
>
> As Jason suggested, I've pulled the first 1 patches into a topic branch.

Uh this was meant to read "first _12_ patches" ofc.
-Daniel

>
> Stephen, can you please add the below to linux-next for the 5.12 merge
> window?
>
> git://anongit.freedesktop.org/drm/drm topic/iomem-mmap-vs-gup
>
> Once this part has landed I'll see what to do with the below part.
>
> Thanks, Daniel
>
> > mm: Add unsafe_follow_pfn
> > media/videobuf1|2: Mark follow_pfn usage as unsafe
> > vfio/type1: Mark follow_pfn as unsafe
> > kvm: pass kvm argument to follow_pfn callsites
> > mm: add mmu_notifier argument to follow_pfn
> >
> > arch/powerpc/kvm/book3s_64_mmu_hv.c | 2 +-
> > arch/powerpc/kvm/book3s_64_mmu_radix.c | 2 +-
> > arch/powerpc/kvm/e500_mmu_host.c | 2 +-
> > arch/x86/kvm/mmu/mmu.c | 8 +-
> > drivers/char/mem.c | 86 +-------------
> > drivers/gpu/drm/exynos/Kconfig | 1 -
> > drivers/gpu/drm/exynos/exynos_drm_g2d.c | 48 ++++----
> > drivers/media/common/videobuf2/Kconfig | 1 -
> > drivers/media/common/videobuf2/Makefile | 1 +
> > .../media/common/videobuf2}/frame_vector.c | 57 ++++-----
> > .../media/common/videobuf2/videobuf2-memops.c | 3 +-
> > drivers/media/platform/omap/Kconfig | 1 -
> > drivers/media/v4l2-core/videobuf-dma-contig.c | 2 +-
> > drivers/misc/habanalabs/Kconfig | 1 -
> > drivers/misc/habanalabs/common/habanalabs.h | 6 +-
> > drivers/misc/habanalabs/common/memory.c | 52 +++-----
> > drivers/pci/pci-sysfs.c | 4 +
> > drivers/pci/proc.c | 6 +
> > drivers/vfio/vfio_iommu_type1.c | 4 +-
> > fs/sysfs/file.c | 11 ++
> > include/linux/ioport.h | 6 +-
> > include/linux/kvm_host.h | 9 +-
> > include/linux/mm.h | 50 +-------
> > include/linux/sysfs.h | 2 +
> > include/media/frame_vector.h | 47 ++++++++
> > include/media/videobuf2-core.h | 1 +
> > kernel/resource.c | 98 ++++++++++++++-
> > mm/Kconfig | 3 -
> > mm/Makefile | 1 -
> > mm/memory.c | 112 +++++++++++++++---
> > mm/nommu.c | 16 ++-
> > security/Kconfig | 13 ++
> > virt/kvm/kvm_main.c | 56 +++++----
> > 33 files changed, 413 insertions(+), 299 deletions(-)
> > rename {mm => drivers/media/common/videobuf2}/frame_vector.c (84%)
> > create mode 100644 include/media/frame_vector.h
> >
> > --
> > 2.29.2
> >
> > _______________________________________________
> > dri-devel mailing list
> > dri-devel@lists.freedesktop.org
> > https://lists.freedesktop.org/mailman/listinfo/dri-devel
>
> --
> Daniel Vetter
> Software Engineer, Intel Corporation
> http://blog.ffwll.ch

--
Daniel Vetter
Software Engineer, Intel Corporation