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a67a88b0b8
linux/arch/s390/pci
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Daniel Vetter a67a88b0b8 s390/pci: remove races against pte updates 
Way back it was a reasonable assumptions that iomem mappings never
change the pfn range they point at. But this has changed:

- gpu drivers dynamically manage their memory nowadays, invalidating
ptes with unmap_mapping_range when buffers get moved

- contiguous dma allocations have moved from dedicated carvetouts to
cma regions. This means if we miss the unmap the pfn might contain
pagecache or anon memory (well anything allocated with GFP_MOVEABLE)

- even /dev/mem now invalidates mappings when the kernel requests that
iomem region when CONFIG_IO_STRICT_DEVMEM is set, see
commit 3234ac664a ("/dev/mem: Revoke mappings when a driver claims the
region")

Accessing pfns obtained from ptes without holding all the locks is
therefore no longer a good idea. Fix this.

Since zpci_memcpy_from|toio seems to not do anything nefarious with
locks we just need to open code get_pfn and follow_pfn and make sure
we drop the locks only after we're done. The write function also needs
the copy_from_user move, since we can't take userspace faults while
holding the mmap sem.

Reviewed-by: Gerald Schaefer <gerald.schaefer@linux.ibm.com>
Signed-off-by: Daniel Vetter <daniel.vetter@intel.com>
Cc: Jason Gunthorpe <jgg@ziepe.ca>
Cc: Dan Williams <dan.j.williams@intel.com>
Cc: Kees Cook <keescook@chromium.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: John Hubbard <jhubbard@nvidia.com>
Cc: Jérôme Glisse <jglisse@redhat.com>
Cc: Jan Kara <jack@suse.cz>
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: Gerald Schaefer <gerald.schaefer@linux.ibm.com>
Cc: linux-s390@vger.kernel.org
Cc: Niklas Schnelle <schnelle@linux.ibm.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Signed-off-by: Niklas Schnelle <schnelle@linux.ibm.com>
Signed-off-by: Heiko Carstens <hca@linux.ibm.com>
2020-11-09 11:21:00 +01:00
..
Makefile s390/pci: consolidate SR-IOV specific code 2020-09-14 11:38:34 +02:00
pci_bus.c VFIO updates for v5.10-rc1 2020-10-22 13:00:44 -07:00
pci_bus.h s390: remove orphaned function declarations 2020-09-30 12:09:54 +02:00
pci_clp.c VFIO updates for v5.10-rc1 2020-10-22 13:00:44 -07:00
pci_debug.c locking/atomic, s390/pci: Remove redundant casts 2019-06-03 12:32:57 +02:00
pci_dma.c dma-mapping: split <linux/dma-mapping.h> 2020-10-06 07:07:03 +02:00
pci_event.c s390/pci: fix hot-plug of PCI function missing bus 2020-11-03 15:12:16 +01:00
pci_insn.c s390/pci: provide support for MIO instructions 2019-04-29 10:47:01 +02:00
pci_iov.c s390/pci: add missing pci_iov.h include 2020-09-16 14:08:47 +02:00
pci_iov.h s390/pci: consolidate SR-IOV specific code 2020-09-14 11:38:34 +02:00
pci_irq.c s390/pci: do not set affinity for floating irqs 2020-04-22 16:20:55 +02:00
pci_mmio.c s390/pci: remove races against pte updates 2020-11-09 11:21:00 +01:00
pci_sysfs.c s390/pci: create zPCI bus 2020-04-28 13:49:46 +02:00
pci.c s390 updates for the 5.10 merge window 2020-10-16 12:36:38 -07:00