This patch tries to implement an device IOTLB for vhost. This could be used with for co-operation with userspace(qemu) implementation of iommu for a secure DMA environment (DMAR) in guest.
The idea is simple. When vhost meets an IOTLB miss, it will request the assistance of userspace to do the translation, this is done through: - Fill the translation request in a preset userspace address (This address is set through ioctl VHOST_SET_IOTLB_REQUEST_ENTRY). - Notify userspace through eventfd (This eventfd was set through ioctl VHOST_SET_IOTLB_FD). When userspace finishes the translation, it will update the vhost IOTLB through VHOST_UPDATE_IOTLB ioctl. Userspace is also in charge of snooping the IOTLB invalidation of IOMMU IOTLB and use VHOST_UPDATE_IOTLB to invalidate the possible entry in vhost. The codes were designed to be architecture independent. It should be easily ported to any architecture. Changes from V1: - support any size/range of updating and invalidation through introducing the interval tree. - convert from per device iotlb request to per virtqueue iotlb request, this solves the possible deadlock in V1. - read/write permission check support. Please review. Thanks Jason Wang (2): vhost: convert pre sorted vhost memory array to interval tree vhost: device IOTLB API drivers/vhost/net.c | 14 +- drivers/vhost/vhost.c | 427 +++++++++++++++++++++++++++++++++++---------- drivers/vhost/vhost.h | 42 ++++- fs/eventfd.c | 3 +- include/uapi/linux/vhost.h | 35 ++++ 5 files changed, 419 insertions(+), 102 deletions(-) -- 2.5.0
