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

Daniel Vetter
2020-11-27T16:43:55Z

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
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