linux/drivers/vfio
Dan Williams 94db151dc8 vfio: disable filesystem-dax page pinning
Filesystem-DAX is incompatible with 'longterm' page pinning. Without
page cache indirection a DAX mapping maps filesystem blocks directly.
This means that the filesystem must not modify a file's block map while
any page in a mapping is pinned. In order to prevent the situation of
userspace holding of filesystem operations indefinitely, disallow
'longterm' Filesystem-DAX mappings.

RDMA has the same conflict and the plan there is to add a 'with lease'
mechanism to allow the kernel to notify userspace that the mapping is
being torn down for block-map maintenance. Perhaps something similar can
be put in place for vfio.

Note that xfs and ext4 still report:

   "DAX enabled. Warning: EXPERIMENTAL, use at your own risk"

...at mount time, and resolving the dax-dma-vs-truncate problem is one
of the last hurdles to remove that designation.

Acked-by: Alex Williamson <alex.williamson@redhat.com>
Cc: Michal Hocko <mhocko@suse.com>
Cc: kvm@vger.kernel.org
Cc: <stable@vger.kernel.org>
Reported-by: Haozhong Zhang <haozhong.zhang@intel.com>
Tested-by: Haozhong Zhang <haozhong.zhang@intel.com>
Fixes: d475c6346a ("dax,ext2: replace XIP read and write with DAX I/O")
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
2018-03-02 18:00:04 -08:00
..
mdev vfio: mdev: make a couple of functions and structure vfio_mdev_driver static 2018-01-09 12:13:08 -07:00
pci vfio-pci: Allow mapping MSIX BAR 2017-12-20 10:05:06 -07:00
platform VFIO Updates for Linux v4.15 2017-11-14 16:47:47 -08:00
Kconfig vfio: Fix build break when SPAPR_TCE_IOMMU=n 2017-02-08 13:13:25 -07:00
Makefile License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
vfio.c vfio: Simplify capability helper 2017-12-20 09:53:54 -07:00
vfio_iommu_spapr_tce.c vfio/spapr: Add cond_resched() for huge updates 2017-10-02 12:39:11 -06:00
vfio_iommu_type1.c vfio: disable filesystem-dax page pinning 2018-03-02 18:00:04 -08:00
vfio_spapr_eeh.c drivers/vfio: Support EEH error injection 2015-05-12 20:33:35 +10:00
virqfd.c vfs: do bulk POLL* -> EPOLL* replacement 2018-02-11 14:34:03 -08:00