US 8,151,032 B2 · Direct memory access filter for virtualized operating systems

Abstract

Described techniques increase runtime performance of workloads executing on a hypervisor by executing virtualization-aware code in an otherwise non virtualization-aware guest operating system. In one implementation, the virtualization-aware code allows workloads direct access to physical hardware devices, while allowing the system memory allocated to the workloads to be overcommitted. In one implementation, a DMA filter driver is inserted into an I/O driver stack to ensure that the target guest physical memory of a DMA transfer is resident before the transfer begins. The DMA filter driver may utilize a cache to track which pages of memory are resident. The cache may also indicate which pages of memory are in use by one or more transfers, enabling the hypervisor to avoid appropriating pages of memory during a transfer.

Claims20

Dependent claims

A computer system comprising:

one or more processors;
system physical memory, accessible by the one or more processors;
and
a first virtual machine having a virtualization-aware module, the virtualization-aware module stored in the system physical memory and executable on the one or more processors to:
receive a first range of guest physical memory addresses independent of a workload of a second virtual machine;
determine whether at least one of the guest physical memory addresses of the range of guest physical memory addresses points to a non-resident portion of guest physical memory;
responsive to determining that at least one of the guest physical memory addresses points to a non-resident portion of guest physical memory, transmit a request to a hypervisor to commit the non-resident portion of guest physical memory, and receive a message from the hypervisor indicating the non-resident portion of guest physical memory has been committed;
and
transmit the range of guest physical memory addresses.

6 more elements

A method comprising:

receiving, at a first virtual machine having a virtualization-aware module, a request from an internal portion of the first virtual machine, the request including a first range of guest physical memory addresses, the virtualization-aware module stored in a memory;
determining, by the first virtual machine, whether at least one of the guest physical memory addresses of the range of guest physical memory addresses points to a non-resident portion of guest physical memory;
responsive to determining that at least one of the guest physical memory addresses points to a non-resident portion of guest physical memory, transmitting a request to a hypervisor to commit the non-resident portion of guest physical memory, and receive a message from the hypervisor indicating the non-resident portion of guest physical memory has been committed;
and
transmitting the range of guest physical memory addresses.

2 more elements

Dependencies are inferred from the claim text.

Direct memory access filter for virtualized operating systems

Life of this patent

Direct memory access filter for virtualized operating systems

Life of this patent

Abstract

Claims20