Ensuring deadlock free operation for peer to peer traffic in an input/output memory management unit (IOMMU)

An input/output memory management unit comprising:

• a cache to cache translation data from memory;
• and
• a control unit coupled to the cache, wherein the control unit is configured to implement address translation and memory protection for memory requests sourced by one or more input/output (I/O) devices;
• wherein the memory requests sourced by the I/O devices travel to the memory in one or more first virtual channels, and wherein the control unit is configured to transmit memory requests sourced by the control unit to the memory in at least a second virtual channel separate from the first virtual channels, and wherein at least a portion of a physical transmission medium from the IOMMU to the memory and from the I/O devices to the memory is shared by the I/O devices and the IOMMU, and wherein transmission of the memory requests sourced by the I/O devices in the one or more first virtual channels and the memory requests sourced by the IOMMU in the second virtual channel ensures that the memory requests sourced by the IOMMU are not blocked by the memory requests sourced by the I/O devices and that the memory requests sourced by the I/O devices are not blocked by the memory requests sourced by the IOMMU.

A computer system comprising:

• one or more input/output (I/O) devices configured to source one or more memory transactions in one or more first virtual channels;
• a memory;
• a physical transmission medium to the memory at least a portion of which is shared by the I/O devices and an I/O memory management unit (IOMMU);
• and
• the IOMMU coupled to the memory via the physical transmission medium and to the I/O devices, wherein the IOMMU is configured to implement address translation and memory protection for the memory operations sourced by one or more input/output (I/O) devices, and wherein the IOMMU is configured to transmit memory requests sourced by the IOMMU to the memory in at least a second virtual channel separate from the first virtual channels, and wherein transmission of the memory requests sourced by the I/O devices in the one or more first virtual channels and the memory requests sourced by the IOMMU in the second virtual channel ensures that the memory requests sourced by the IOMMU are not blocked by the memory requests sourced by the I/O devices and that the memory requests sourced by the I/O devices are not blocked by the memory requests sourced by the IOMMU.