With the introduction of the new object and its infrastructure, update the doc to reflect that.
Reviewed-by: Jason Gunthorpe jgg@nvidia.com Reviewed-by: Kevin Tian kevin.tian@intel.com Reviewed-by: Lu Baolu baolu.lu@linux.intel.com Signed-off-by: Nicolin Chen nicolinc@nvidia.com --- Documentation/userspace-api/iommufd.rst | 12 ++++++++++++ 1 file changed, 12 insertions(+)
diff --git a/Documentation/userspace-api/iommufd.rst b/Documentation/userspace-api/iommufd.rst index b0df15865dec..03f7510384d2 100644 --- a/Documentation/userspace-api/iommufd.rst +++ b/Documentation/userspace-api/iommufd.rst @@ -124,6 +124,17 @@ Following IOMMUFD objects are exposed to userspace: used to allocate a vEVENTQ. Each vIOMMU can support multiple types of vEVENTS, but is confined to one vEVENTQ per vEVENTQ type.
+- IOMMUFD_OBJ_HW_QUEUE, representing a hardware accelerated queue, as a subset + of IOMMU's virtualization features, for the IOMMU HW to directly read or write + the virtual queue memory owned by a guest OS. This HW-acceleration feature can + allow VM to work with the IOMMU HW directly without a VM Exit, so as to reduce + overhead from the hypercalls. Along with the HW QUEUE object, iommufd provides + user space an mmap interface for VMM to mmap a physical MMIO region from the + host physical address space to the guest physical address space, allowing the + guest OS to directly control the allocated HW QUEUE. Thus, when allocating a + HW QUEUE, the VMM must request a pair of mmap info (offset/length) and pass in + exactly to an mmap syscall via its offset and length arguments. + All user-visible objects are destroyed via the IOMMU_DESTROY uAPI.
The diagrams below show relationships between user-visible objects and kernel @@ -270,6 +281,7 @@ User visible objects are backed by following datastructures: - iommufd_viommu for IOMMUFD_OBJ_VIOMMU. - iommufd_vdevice for IOMMUFD_OBJ_VDEVICE. - iommufd_veventq for IOMMUFD_OBJ_VEVENTQ. +- iommufd_hw_queue for IOMMUFD_OBJ_HW_QUEUE.
Several terminologies when looking at these datastructures: