On Tue, 30 Aug 2016 11:06:50 +0800
Jason Wang <address@hidden> wrote:
Currently, all virtio devices bypass IOMMU completely. This is because
address_space_memory is assumed and used during DMA emulation. This
patch converts the virtio core API to use DMA API. This idea is
- introducing a new transport specific helper to query the dma address
space. (only pci version is implemented).
- query and use this address space during virtio device guest memory
accessing when iommu platform (VIRTIO_F_IOMMU_PLATFORM) was enabled
for this device.
Cc: Michael S. Tsirkin <address@hidden>
Cc: Stefan Hajnoczi <address@hidden>
Cc: Kevin Wolf <address@hidden>
Cc: Amit Shah <address@hidden>
Cc: Paolo Bonzini <address@hidden>
Cc: address@hidden
Signed-off-by: Jason Wang <address@hidden>
---
hw/block/virtio-blk.c | 2 +-
hw/char/virtio-serial-bus.c | 3 +-
hw/scsi/virtio-scsi.c | 4 ++-
hw/virtio/virtio-pci.c | 14 +++++++++
hw/virtio/virtio.c | 62 ++++++++++++++++++++++++---------------
include/hw/virtio/virtio-access.h | 43 ++++++++++++++++++++-------
include/hw/virtio/virtio-bus.h | 1 +
include/hw/virtio/virtio.h | 8 +++--
8 files changed, 98 insertions(+), 39 deletions(-)
diff --git a/include/hw/virtio/virtio-access.h
b/include/hw/virtio/virtio-access.h
index 440b455..4071dad 100644
--- a/include/hw/virtio/virtio-access.h
+++ b/include/hw/virtio/virtio-access.h
@@ -17,12 +17,25 @@
#define QEMU_VIRTIO_ACCESS_H
#include "hw/virtio/virtio.h"
+#include "hw/virtio/virtio-bus.h"
#include "exec/address-spaces.h"
#if defined(TARGET_PPC64) || defined(TARGET_ARM)
#define LEGACY_VIRTIO_IS_BIENDIAN 1
#endif
+static inline AddressSpace *virtio_get_dma_as(VirtIODevice *vdev)
+{
+ BusState *qbus = qdev_get_parent_bus(DEVICE(vdev));
+ VirtioBusClass *k = VIRTIO_BUS_GET_CLASS(qbus);
+
+ if (virtio_host_has_feature(vdev, VIRTIO_F_IOMMU_PLATFORM) &&
+ k->get_dma_as) {
+ return k->get_dma_as(qbus->parent);
+ }
+ return &address_space_memory;
+}
One thing I'm a bit worried about is that we're introducing a check
even if we know that the device will never support
VIRTIO_F_IOMMU_PLATFORM (i.e. virtio-ccw). The qom incantations will
add cycles to any invocation of this.
Is the address space likely to change during device lifetime? Can we
cache it in some way?