linux/drivers/vfio
Alex Williamson bc93b9ae01 vfio-pci: Avoid recursive read-lock usage
A down_read on memory_lock is held when performing read/write accesses
to MMIO BAR space, including across the copy_to/from_user() callouts
which may fault.  If the user buffer for these copies resides in an
mmap of device MMIO space, the mmap fault handler will acquire a
recursive read-lock on memory_lock.  Avoid this by reducing the lock
granularity.  Sequential accesses requiring multiple ioread/iowrite
cycles are expected to be rare, therefore typical accesses should not
see additional overhead.

VGA MMIO accesses are expected to be non-fatal regardless of the PCI
memory enable bit to allow legacy probing, this behavior remains with
a comment added.  ioeventfds are now included in memory access testing,
with writes dropped while memory space is disabled.

Fixes: abafbc551f ("vfio-pci: Invalidate mmaps and block MMIO access on disabled memory")
Reported-by: Zhiyi Guo <zhguo@redhat.com>
Tested-by: Zhiyi Guo <zhguo@redhat.com>
Reviewed-by: Cornelia Huck <cohuck@redhat.com>
Signed-off-by: Alex Williamson <alex.williamson@redhat.com>
2020-08-17 11:08:18 -06:00
..
mdev vfio/mdev: Fix reference count leak in add_mdev_supported_type 2020-05-29 16:07:18 -06:00
pci vfio-pci: Avoid recursive read-lock usage 2020-08-17 11:08:18 -06:00
platform vfio: platform: Switch to platform_get_irq_optional() 2020-03-24 09:26:30 -06:00
Kconfig docs: driver-api: add a series of orphaned documents 2019-07-15 11:03:02 -03:00
Makefile License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
vfio_iommu_spapr_tce.c vfio/spapr_tce: convert get_user_pages() --> pin_user_pages() 2020-07-27 13:43:38 -06:00
vfio_iommu_type1.c VFIO updates for v5.9-rc1 2020-08-12 12:09:36 -07:00
vfio_spapr_eeh.c treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 500 2019-06-19 17:09:55 +02:00
vfio.c vfio: Cleanup allowed driver naming 2020-07-27 13:43:36 -06:00
virqfd.c treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 500 2019-06-19 17:09:55 +02:00