On Mon, 23 Nov 2015 15:41:11 +0800 Jason Wang <jasow...@redhat.com> 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 > > With this virtiodevices will not bypass IOMMU anymore. Little tested with > intel_iommu=on with virtio guest DMA series posted in > https://lkml.org/lkml/2015/10/28/64. > > TODO: > - Feature bit for this I'm still not convinced about that feature bit stuff. It just feels wrong to use a mechanism that conveys negotiable device features to configure what is basically a platform/hypervisor feature. I'd rather see this out of the virtio layer and into the pci layer. > - Implement this for all transports Is it OK to just keep a fallback to today's implementation for transports for which the iommu concept doesn't make sense and that will always have an identity mapping? > > Signed-off-by: Jason Wang <jasow...@redhat.com> > --- > hw/block/virtio-blk.c | 2 +- > hw/char/virtio-serial-bus.c | 2 +- > hw/scsi/virtio-scsi.c | 2 +- > hw/virtio/virtio-pci.c | 9 +++++++++ > hw/virtio/virtio.c | 36 +++++++++++++++++++-------------- > include/hw/virtio/virtio-access.h | 42 > +++++++++++++++++++++++++++++---------- > include/hw/virtio/virtio-bus.h | 1 + > include/hw/virtio/virtio.h | 2 +- > 8 files changed, 67 insertions(+), 29 deletions(-) FWIW, this doesn't seem to break for the s390-ccw-virtio machine (only snifftested).
