Virtual machine block substitution

摘要

Techniques are described to allow substation of blocks into a virtual machine image of an executing virtual machine. A patch may be applied to a first virtual machine image. One or more blocks modified by the patch are identified and copied to a host having a virtual machine executing from a virtual machine image that is based on the first virtual machine image (prior to the patch). While the virtual machine is executing, the substitution blocks are applied (supersede) corresponding original blocks in the virtual machine image. A guest operating system in the virtual machine may either begin using an executable file in a substitution block. In addition, the guest operating system may be forced to flush from memory and cache executable code replaced by the substitution block.

主权项

1. A computer-implemented method of updating a virtual machine, the method comprising:
executing a hypervisor on a host computer, the hypervisor managing execution of the virtual machine on the host computer, wherein a guest operating system is configured to execute on the virtual machine, the hypervisor configured to provide the virtual machine with block-based access to a virtual machine image, the virtual machine image comprised of blocks; receiving a substitution block at the host computer; and while the virtual machine is live, replacing, by the hypervisor, a target block in the virtual machine image with the substitution block, the target block comprising one of the blocks of the virtual machine image, the hypervisor managing the blocks of the virtual machine image and, when the virtual machine is executing, presenting the blocks of the virtual machine image, including the substitution block, to the virtual machine as a virtualized disk.