With the introduction of the new object and its infrastructure, update the doc to reflect that.
Signed-off-by: Nicolin Chen nicolinc@nvidia.com --- Documentation/userspace-api/iommufd.rst | 15 +++++++++++++++ 1 file changed, 15 insertions(+)
diff --git a/Documentation/userspace-api/iommufd.rst b/Documentation/userspace-api/iommufd.rst index b0df15865dec..ed32713a97a3 100644 --- a/Documentation/userspace-api/iommufd.rst +++ b/Documentation/userspace-api/iommufd.rst @@ -124,6 +124,20 @@ 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_VQUEUE, representing a hardware accelerated virtual 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 + allows VM to work with the IOMMU HW directly without a VM Exit, i.e. reducing + overhead from the hypercalls. Along with this vQUEUE 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 control the allocated vQUEUE HW. Thus, when allocating a vQUEUE, + the VMM must request a pair of VMA info (vm_pgoff/size) for an mmap syscall. + The length argument of an mmap syscall can be smaller than the given size for + a partial mmap, but the addr argument of the mmap syscall should never offset + from the returned vm_pgoff, which implies that an mmap will always start from + the beginning of the physical MMIO region. + All user-visible objects are destroyed via the IOMMU_DESTROY uAPI.
The diagrams below show relationships between user-visible objects and kernel @@ -270,6 +284,7 @@ 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_vqueue for IOMMUFD_OBJ_VQUEUE.
Several terminologies when looking at these datastructures: