Efficient memory and resource management
The present system enables passing a pointer, associated with accessing data in a memory, to an input/output (I/O) device via an input/output memory management unit (IOMMU). The I/O device accesses the data in the memory via the IOMMU without copying the data into a local I/O device memory. The I/O device can perform an operation on the data in the memory based on the pointer, such that I/O device accesses the memory without expensive copies.
1. A method comprising:
receiving, by an I/O device, a mapped pointer, the mapped pointer pointing to data residing in a system memory, wherein the mapped pointer is received via an input/output memory management unit (IOMMU);
accessing, by the I/O device, the data in the system memory via the IOMMU without copying the data into a local memory of the I/O device memory; and
performing, by the I/O device, an operation on the data directly in the system memory based on the mapped pointer; and nested paging transactions provided from the IOMMU.
2. The method of claim 1 , wherein the IOMMU is configured to pass the mapped pointer without needing intervention by a hypervisor or guest operating system (OS).
3. The method of claim 1 , wherein the mapped pointer is configured to be usable by the I/O device, and a process running in a virtual machine, without reconfiguring the pointer.
4. The method of claim 1 , wherein the data comprises image data.
5. The method of claim 1 , wherein the system memory and the I/O device operate out of a same guest virtual address space to provide for direct manipulation by the guest OS of the data in the system memory.
6. The method of claim 1 , wherein the performing comprises:
using nested translation information from the nested transactions without using a guest translation layer,
wherein the guest translation layer is implemented for separation of a guest process and the I/O device.
7. An apparatus comprising:
an input/output memory management unit (IOMMU) configured to:
pass a mapped pointer, the mapped pointer pointing to data residing in a system memory, to an input/output (I/O) device, wherein the I/O device accesses the data in the system memory via the IOMMU without copying the data into a local I/O device memory and
provide, to the I/O device nested paging transactions, wherein the mapped pointer and nested transactions are configured to enable the I/O device to perform an operation on the data in the system memory.
8. The apparatus of claim 7 , wherein the IOMMU is configured to pass the mapped pointer without needing intervention by a hypervisor or guest operating system (OS).
9. The apparatus of claim 7 , wherein the mapped pointer is configured to be usable by the I/O device, and a process running in a virtual machine, without reconfiguring the mapped pointer.
10. The apparatus of claim 7 , wherein the data in the system memory comprises image data.
11. The apparatus of claim 7 , wherein the system memory and I/O device operate out of a same guest virtual address space to provide for direct manipulation by the guest OS of the data in the system memory.
12. The apparatus of claim 7 , wherein:
nested translation information from the nested transactions is used without using a guest translation layer; and
the guest translation layer is implemented to separate a guest process and the I/O device.