Will Deacon c7070619f3 vring: Force use of DMA API for ARM-based systems with legacy devices ... Booting Linux on an ARM fastmodel containing an SMMU emulation results in an unexpected I/O page fault from the legacy virtio-blk PCI device: [ 1.211721] arm-smmu-v3 2b400000.smmu: event 0x10 received: [ 1.211800] arm-smmu-v3 2b400000.smmu: 0x00000000fffff010 [ 1.211880] arm-smmu-v3 2b400000.smmu: 0x0000020800000000 [ 1.211959] arm-smmu-v3 2b400000.smmu: 0x00000008fa081002 [ 1.212075] arm-smmu-v3 2b400000.smmu: 0x0000000000000000 [ 1.212155] arm-smmu-v3 2b400000.smmu: event 0x10 received: [ 1.212234] arm-smmu-v3 2b400000.smmu: 0x00000000fffff010 [ 1.212314] arm-smmu-v3 2b400000.smmu: 0x0000020800000000 [ 1.212394] arm-smmu-v3 2b400000.smmu: 0x00000008fa081000 [ 1.212471] arm-smmu-v3 2b400000.smmu: 0x0000000000000000 <system hangs failing to read partition table> This is because the legacy virtio-blk device is behind an SMMU, so we have consequently swizzled its DMA ops and configured the SMMU to translate accesses. This then requires the vring code to use the DMA API to establish translations, otherwise all transactions will result in fatal faults and termination. Given that ARM-based systems only see an SMMU if one is really present (the topology is all described by firmware tables such as device-tree or IORT), then we can safely use the DMA API for all legacy virtio devices. Modern devices can advertise the prescense of an IOMMU using the VIRTIO_F_IOMMU_PLATFORM feature flag. Cc: Andy Lutomirski <luto@kernel.org> Cc: Michael S. Tsirkin <mst@redhat.com> Cc: <stable@vger.kernel.org> Fixes: 876945dbf6 ("arm64: Hook up IOMMU dma_ops") Signed-off-by: Will Deacon <will.deacon@arm.com> Signed-off-by: Michael S. Tsirkin <mst@redhat.com> Acked-by: Marc Zyngier <marc.zyngier@arm.com>		2017-01-25 00:33:11 +02:00
..
Kconfig	docs: fix locations of several documents that got moved	2016-10-24 08:12:35 -02:00
Makefile	Add virtio-input driver.	2015-03-29 12:13:52 +10:30
virtio_balloon.c	virtio: update balloon size in balloon "probe"	2016-10-31 00:21:41 +02:00
virtio_input.c	virtio: make find_vqs() checkpatch.pl-friendly	2016-01-12 20:47:06 +02:00
virtio_mmio.c	virtio_mmio: Set DMA masks appropriately	2017-01-25 00:33:10 +02:00
virtio_pci_common.c	virtio_pci: split vp_try_to_find_vqs into INTx and MSI-X variants	2016-12-16 00:12:49 +02:00
virtio_pci_common.h	virtio_pci: use pci_alloc_irq_vectors	2016-12-16 00:12:47 +02:00
virtio_pci_legacy.c	virtio_pci: Limit DMA mask to 44 bits for legacy virtio devices	2016-10-31 00:21:39 +02:00
virtio_pci_modern.c	virtio_pci_modern: fix complaint by sparse	2016-12-15 06:39:46 +02:00
virtio_ring.c	vring: Force use of DMA API for ARM-based systems with legacy devices	2017-01-25 00:33:11 +02:00
virtio.c	virtio: fix memory leak of virtio ida cache layers	2015-12-07 17:28:01 +02:00