https://github.com/torvalds/linux
Revision a0be1db4304f51c99af6b6e515549794182a94df authored by Will Deacon on 14 September 2016, 16:33:26 UTC, committed by Michael S. Tsirkin on 30 October 2016, 22:21:39 UTC
Legacy virtio defines the virtqueue base using a 32-bit PFN field, with
a read-only register indicating a fixed page size of 4k.

This can cause problems for DMA allocators that allocate top down from
the DMA mask, which is set to 64 bits. In this case, the addresses are
silently truncated to 44-bit, leading to IOMMU faults, failure to read
from the queue or data corruption.

This patch restricts the coherent DMA mask for legacy PCI virtio devices
to 44 bits, which matches the specification.

Cc: stable@vger.kernel.org
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Michael S. Tsirkin <mst@redhat.com>
Cc: Benjamin Serebrin <serebrin@google.com>
Signed-off-by: Will Deacon <will.deacon@arm.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
1 parent a909d3e
History
Tip revision: a0be1db4304f51c99af6b6e515549794182a94df authored by Will Deacon on 14 September 2016, 16:33:26 UTC
virtio_pci: Limit DMA mask to 44 bits for legacy virtio devices
Tip revision: a0be1db
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