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linux/drivers/vfio
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Niklas Schnelle 4ba7d17f2b vfio/type1: Respect IOMMU reserved regions in vfio_test_domain_fgsp() 
[ Upstream commit 895c0747f7 ]

Since commit cbf7827bc5 ("iommu/s390: Fix potential s390_domain
aperture shrinking") the s390 IOMMU driver uses reserved regions for the
system provided DMA ranges of PCI devices. Previously it reduced the
size of the IOMMU aperture and checked it on each mapping operation.
On current machines the system denies use of DMA addresses below 2^32 for
all PCI devices.

Usually mapping IOVAs in a reserved regions is harmless until a DMA
actually tries to utilize the mapping. However on s390 there is
a virtual PCI device called ISM which is implemented in firmware and
used for cross LPAR communication. Unlike real PCI devices this device
does not use the hardware IOMMU but inspects IOMMU translation tables
directly on IOTLB flush (s390 RPCIT instruction). If it detects IOVA
mappings outside the allowed ranges it goes into an error state. This
error state then causes the device to be unavailable to the KVM guest.

Analysing this we found that vfio_test_domain_fgsp() maps 2 pages at DMA
address 0 irrespective of the IOMMUs reserved regions. Even if usually
harmless this seems wrong in the general case so instead go through the
freshly updated IOVA list and try to find a range that isn't reserved,
and fits 2 pages, is PAGE_SIZE * 2 aligned. If found use that for
testing for fine grained super pages.

Fixes: af029169b8 ("vfio/type1: Check reserved region conflict and update iova list")
Signed-off-by: Niklas Schnelle <schnelle@linux.ibm.com>
Reviewed-by: Matthew Rosato <mjrosato@linux.ibm.com>
Reviewed-by: Jason Gunthorpe <jgg@nvidia.com>
Link: https://lore.kernel.org/r/20230110164427.4051938-2-schnelle@linux.ibm.com
Signed-off-by: Alex Williamson <alex.williamson@redhat.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
History 2023-02-01 08:34:36 +01:00
..
fsl-mc vfio/fsl-mc: Use the new device life cycle helpers 2022-09-21 14:15:11 -06:00
mdev vfio/mdev: add mdev available instance checking to the core 2022-10-04 12:06:58 -06:00
pci vfio/pci: Check the device set open count on reset 2022-11-10 12:03:36 -07:00
platform vfio: platform: Do not pass return buffer to ACPI _RST method 2022-12-31 13:32:38 +01:00
container.c vfio: Change vfio_group->group_rwsem to a mutex 2022-10-04 12:06:58 -06:00
iova_bitmap.c vfio/iova_bitmap: refactor iova_bitmap_set() to better handle page boundaries 2022-12-31 13:32:41 +01:00
Kconfig vfio: Introduce the DMA logging feature support 2022-09-08 12:59:00 -06:00
Makefile vfio: Move container code into drivers/vfio/container.c 2022-09-22 15:46:06 -06:00
vfio.h vfio: Make the group FD disassociate from the iommu_group 2022-10-07 08:10:52 -06:00
vfio_iommu_spapr_tce.c vfio/spapr_tce: Fix the comment 2022-07-22 16:24:47 -06:00
vfio_iommu_type1.c vfio/type1: Respect IOMMU reserved regions in vfio_test_domain_fgsp() 2023-02-01 08:34:36 +01:00
vfio_main.c vfio: Export the device set open count 2022-11-10 12:03:36 -07:00
vfio_spapr_eeh.c treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 500 2019-06-19 17:09:55 +02:00
virqfd.c vfio/virqfd: Drain events from eventfd in virqfd_wakeup() 2020-11-15 09:49:10 -05:00