linux/drivers/vhost
Stefano Garzarella e13a6915a0 vhost/vsock: add IOTLB API support
This patch enables the IOTLB API support for vhost-vsock devices,
allowing the userspace to emulate an IOMMU for the guest.

These changes were made following vhost-net, in details this patch:
- exposes VIRTIO_F_ACCESS_PLATFORM feature and inits the iotlb
  device if the feature is acked
- implements VHOST_GET_BACKEND_FEATURES and
  VHOST_SET_BACKEND_FEATURES ioctls
- calls vq_meta_prefetch() before vq processing to prefetch vq
  metadata address in IOTLB
- provides .read_iter, .write_iter, and .poll callbacks for the
  chardev; they are used by the userspace to exchange IOTLB messages

This patch was tested specifying "intel_iommu=strict" in the guest
kernel command line. I used QEMU with a patch applied [1] to fix a
simple issue (that patch was merged in QEMU v5.2.0):
    $ qemu -M q35,accel=kvm,kernel-irqchip=split \
           -drive file=fedora.qcow2,format=qcow2,if=virtio \
           -device intel-iommu,intremap=on,device-iotlb=on \
           -device vhost-vsock-pci,guest-cid=3,iommu_platform=on,ats=on

[1] https://lists.gnu.org/archive/html/qemu-devel/2020-10/msg09077.html

Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
Signed-off-by: Stefano Garzarella <sgarzare@redhat.com>
Link: https://lore.kernel.org/r/20201223143638.123417-1-sgarzare@redhat.com
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
Acked-by: Jason Wang <jasowang@redhat.com>
2020-12-27 05:49:01 -05:00
..
iotlb.c vhost: Fix documentation 2020-09-24 05:54:36 -04:00
Kconfig vhost_vdpa: implement IRQ offloading in vhost_vdpa 2020-08-05 11:08:42 -04:00
Makefile vhost: introduce vDPA-based backend 2020-04-02 10:41:40 -04:00
net.c virtio: fixes, features 2020-08-11 14:34:17 -07:00
scsi.c vhost scsi: fix error return code in vhost_scsi_set_endpoint() 2020-12-18 16:14:31 -05:00
test.c tools/virtio: Add --reset 2020-06-22 12:34:21 -04:00
test.h tools/virtio: Add --reset 2020-06-22 12:34:21 -04:00
vdpa.c vhost_vdpa: switch to vmemdup_user() 2020-12-18 16:14:28 -05:00
vhost.c vhost: add helper to check if a vq has been setup 2020-11-15 17:30:54 -05:00
vhost.h vhost: add helper to check if a vq has been setup 2020-11-15 17:30:54 -05:00
vringh.c vringh: fix vringh_iov_push_*() documentation 2020-11-25 04:22:48 -05:00
vsock.c vhost/vsock: add IOTLB API support 2020-12-27 05:49:01 -05:00