IOMMU Fixes for v5.15-rc1
Including:
- Intel VT-d:
- PASID leakage in intel_svm_unbind_mm();
- Deadlock in intel_svm_drain_prq().
- AMD IOMMU: Fixes for an unhandled page-fault bug when AVIC is used
for a KVM guest.
- Make CONFIG_IOMMU_DEFAULT_DMA_LAZY architecture instead of IOMMU
driver dependent
iommu: Clarify default domain Kconfig
Although strictly it is the AMD and Intel drivers which have an existing
expectation of lazy behaviour by default, it ends up being rather
unintuitive to describe this literally in Kconfig. Express it instead as
an architecture dependency, to clarify that it is a valid config-time
decision. The end result is the same since virtio-iommu doesn't support
lazy mode and thus falls back to strict at runtime regardless.
The per-architecture disparity is a matter of historical expectations:
the AMD and Intel drivers have been lazy by default since 2008, and
changing that gets noticed by people asking where their I/O throughput
has gone. Conversely, Arm-based systems with their wider assortment of
IOMMU drivers mostly only support strict mode anyway; only the Arm SMMU
drivers have later grown support for passthrough and lazy mode, for
users who wanted to explicitly trade off isolation for performance.
These days, reducing the default level of isolation in a way which may
go unnoticed by users who expect otherwise hardly seems worth risking
for the sake of one line of Kconfig, so here's where we are.
Reported-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Robin Murphy <robin.murphy@arm.com>
Link: https://lore.kernel.org/r/69a0c6f17b000b54b8333ee42b3124c1d5a869e2.1631105737.git.robin.murphy@arm.com
Signed-off-by: Joerg Roedel <jroedel@suse.de>
1 file changed
