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linux/drivers/vfio
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Alex Williamson 9f43f70dcc vfio/type1: Remove locked page accounting workqueue 
commit 0cfef2b741 upstream.

If the mmap_sem is contented then the vfio type1 IOMMU backend will
defer locked page accounting updates to a workqueue task.  This has a
few problems and depending on which side the user tries to play, they
might be over-penalized for unmaps that haven't yet been accounted or
race the workqueue to enter more mappings than they're allowed.  The
original intent of this workqueue mechanism seems to be focused on
reducing latency through the ioctl, but we cannot do so at the cost
of correctness.  Remove this workqueue mechanism and update the
callers to allow for failure.  We can also now recheck the limit under
write lock to make sure we don't exceed it.

vfio_pin_pages_remote() also now necessarily includes an unwind path
which we can jump to directly if the consecutive page pinning finds
that we're exceeding the user's memory limits.  This avoids the
current lazy approach which does accounting and mapping up to the
fault, only to return an error on the next iteration to unwind the
entire vfio_dma.

Reviewed-by: Peter Xu <peterx@redhat.com>
Reviewed-by: Kirti Wankhede <kwankhede@nvidia.com>
Signed-off-by: Alex Williamson <alex.williamson@redhat.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
History 2017-05-20 14:28:38 +02:00
..
pci vfio/pci: Fix integer overflows, bitmask check 2016-10-26 13:49:29 -06:00
platform vfio: platform: mark symbols static where possible 2016-09-13 16:11:37 -06:00
Kconfig vfio: Include No-IOMMU mode 2015-12-21 15:28:11 -07:00
Makefile vfio: Split virqfd into a separate module for vfio bus drivers 2015-03-17 08:33:38 -06:00
vfio.c vfio: fix possible use after free of vfio group 2016-07-14 14:28:16 -06:00
vfio_iommu_spapr_tce.c vfio/spapr: Postpone default window creation 2017-03-22 12:43:38 +01:00
vfio_iommu_type1.c vfio/type1: Remove locked page accounting workqueue 2017-05-20 14:28:38 +02:00
vfio_spapr_eeh.c drivers/vfio: Support EEH error injection 2015-05-12 20:33:35 +10:00
virqfd.c vfio: Split virqfd into a separate module for vfio bus drivers 2015-03-17 08:33:38 -06:00