Managing I/O memory isolation (iommu

Managing I/O memory isolation (iommu_api.h)

The API is defined in the sysroot-*-kos/include/coresrv/iommu/iommu_api.h header file from the KasperskyOS SDK.

The API is intended for managing the isolation of physical memory regions used by devices on a PCIe bus for DMA. (Isolation is provided by the IOMMU.)

Information about API functions is provided in the table below.

Using the API

A device on the PCIe bus cannot use DMA unless the device is attached to the IOMMU domain. After a device is attached to the IOMMU domain, the device can access all DMA buffers that are associated with this IOMMU domain. A device can be attached to only one IOMMU domain at a time, but multiple devices can be attached to the same IOMMU domain. A DMA buffer can be associated with multiple IOMMU domains at the same time. Each process is associated with a separate IOMMU domain.

The API attaches devices on the PCIe bus to an IOMMU domain associated with the calling process, and performs the inverse operation. A device is normally attached to an IOMMU domain when its driver is initialized. A device is usually detached from an IOMMU domain when errors are encountered during driver initialization or driver finalization.

A DMA buffer is associated with an IOMMU domain when calling the KnIoDmaBegin() function that is included in the API dma.h.

Information about API functions

iommu_api.h functions

Function	Information about the function
`KnIommuAttachDevice()`	Purpose Attaches a device on a PCIe bus to the IOMMU domain associated with the calling process. Parameters [in] `bdf` – address of the device on the PCIe bus in BDF format. Returned values If successful, the function returns `rcOk`, otherwise it returns an error code. Additional information If IOMMU is not enabled, `rcOk` is returned.
`KnIommuDetachDevice()`	Purpose Detaches a device on a PCIe bus from the IOMMU domain associated with the calling process. Parameters [in] `bdf` – address of the device on the PCIe bus in BDF format. Returned values If successful, the function returns `rcOk`, otherwise it returns an error code. Additional information If IOMMU is not enabled, `rcOk` is returned.

Function

Information about the function

KnIommuAttachDevice()

Purpose

Attaches a device on a PCIe bus to the IOMMU domain associated with the calling process.

Parameters

[in] bdf – address of the device on the PCIe bus in BDF format.

Returned values

If successful, the function returns rcOk, otherwise it returns an error code.

Additional information

If IOMMU is not enabled, rcOk is returned.

KnIommuDetachDevice()