Abstract: A provisioning server automatically configures a virtual machine (VM) according to user specifications and then deploys the VM on a physical host. The user may either choose from a list of pre-configured, ready-to-deploy VMs, or he may select which hardware, operating system and application(s) he would like the VM to have. The provisioning server then configures the VM accordingly, if the desired configuration is available, or it applies heuristics to configure a VM that best matches the user's request if it isn't. The invention also includes mechanisms for monitoring the status of VMs and hosts, for migrating VMs between hosts, and for creating a network of VMs.

Abstract: In a computer system supporting execution of virtualization software and at least one instance of virtual system hardware, an interface is provided into the virtualization software to allow a program to directly define the access characteristics of its program data stored in physical memory. The technique includes providing data identifying memory pages and their access characteristics to the virtualization software which then derives the memory access characteristics from the specified data. Optionally, the program may also specify a pre-defined function to be performed upon the occurrence of a fault associated with access to an identified memory page. In this manner, programs operating both internal and external to the virtualization software can protect his memory pages, without intermediation by the operating system software.

Abstract: To generate a checkpoint for a virtual machine (VM), first, while the VM is still running, a copy-on-write (COW) disk file is created pointing to a parent disk file that the VM is using. Next, the VM is stopped, the VM's memory is marked COW, the device state of the VM is saved to memory, the VM is switched to use the COW disk file, and the VM begins running again for substantially the remainder of the checkpoint generation. Next, the device state that was stored in memory and the unmodified VM memory pages are saved to a checkpoint file. Also, a copy may be made of the parent disk file for retention as part of the checkpoint, or the original parent disk file may be retained as part of the checkpoint. If a copy of the parent disk file was made, then the COW disk file may be committed to the original parent disk file.

Abstract: A virtual-machine-based system provides a control-transfer mechanism to invoke a user-mode application handler from existing virtual hardware directly, without going through an operating system kernel running in the virtual machine. A virtual machine monitor calls directly to the guest user-mode handler and the handler transfers control back to the virtual machine monitor, without involving the guest operating system.

Abstract: A provisioning server automatically configures a virtual machine (VM) according to user specifications and then deploys the VM on a physical host. The user may either choose from a list of pre-configured, ready-to-deploy VMs, or he may select which hardware, operating system and application(s) he would like the VM to have. The provisioning server then configures the VM accordingly, if the desired configuration is available, or it applies heuristics to configure a VM that best matches the user's request if it isn't. The invention also includes mechanisms for monitoring the status of VMs and hosts, for migrating VMs between hosts, and for creating a network of VMs.

Abstract: A method is provided for executing guest computations in a virtual machine of a virtualization system and forcing execution of registered code into an execution context of the guest. The forcing is performed from the virtualization system based on an execution trigger monitored without reliance on functionality of the guest software.

Abstract: A checkpointing fault tolerance network architecture enables a backup computer system to be remotely located from a primary computer system. An intermediary computer system is situated between the primary computer system and the backup computer system to manage the transmission of checkpoint information to the backup VM in an efficient manner. The intermediary computer system is networked to the primary VM through a first connection and is networked to the backup VM through a second connection. The intermediary computer system identifies updated data corresponding to memory pages that have been least recently modified by the primary VM and transmits such updated data to the backup VM through the first connection. In such manner, the intermediary computer system holds back updated data corresponding to more recently modified memory pages, since such memory pages may be more likely to be updated again in the future.

Abstract: A checkpointing fault tolerance network architecture enables a backup computer system to be remotely located from a primary computer system. An intermediary computer system is situated between the primary computer system and the backup computer system to manage the transmission of checkpoint information to the backup VM in an efficient manner. The intermediary computer system is networked to the primary VM through a high bandwidth connection but is networked to the backup VM through a lower bandwidth connection. The intermediary computer system identifies updated data corresponding to memory pages that have been least recently modified by the primary VM and transmits such updated data to the backup VM through the low bandwidth connection. In such manner, the intermediary computer system economizes the bandwidth capacity of the low bandwidth connection, holding back updated data corresponding to more recently modified memory pages, since such memory pages may be more likely to be updated again in the future.

Abstract: A checkpointing fault tolerance network architecture enables a backup computer system to be remotely located from a primary computer system. An intermediary computer system is situated between the primary computer system and the backup computer system to manage the transmission of checkpoint information to the backup VM in an efficient manner. The intermediary computer system is networked to the primary VM through a high bandwidth connection but is networked to the backup VM through a lower bandwidth connection. The intermediary computer system identifies updated data corresponding to memory pages that have been least recently modified by the primary VM and transmits such updated data to the backup VM through the low bandwidth connection. In such manner, the intermediary computer system economizes the bandwidth capacity of the low bandwidth connection, holding back updated data corresponding to more recently modified memory pages, since such memory pages may be more likely to be updated again in the future.

Abstract: For a virtual memory of a virtualized computer system in which a virtual page is mapped to a guest physical page which is backed by a machine page and in which a shadow page table entry directly maps the virtual page to the machine page, reverse mappings of guest physical pages are optimized by removing the reverse mappings of certain immutable guest physical pages. An immutable guest physical memory page is identified, and existing reverse mappings corresponding to the immutable guest physical page are removed. New reverse mappings corresponding to the identified immutable guest physical page are no longer added.

Abstract: To generate a checkpoint for a virtual machine (VM), first, while the VM is still running, a copy-on-write (COW) disk file is created pointing to a parent disk file that the VM is using. Next, the VM is stopped, the VM's memory is marked COW, the device state of the VM is saved to memory, the VM is switched to use the COW disk file, and the VM begins running again for substantially the remainder of the checkpoint generation. Next, the device state that was stored in memory and the unmodified VM memory pages are saved to a checkpoint file. Also, a copy may be made of the parent disk file for retention as part of the checkpoint, or the original parent disk file may be retained as part of the checkpoint. If a copy of the parent disk file was made, then the COW disk file may be committed to the original parent disk file.

Abstract: The invention is used in a virtual machine monitor for a multiprocessing system that includes a virtual memory system. During a software-based processing of a guest instruction, including translating or interpreting a guest instruction, mappings between virtual addresses and physical addresses are retained in memory until processing of the guest instruction is completed. The retained mappings may be cleared after each guest instruction has been processed, or after multiple guest instructions have been processed. Information may also be stored to indicate that an attempt to map a virtual address to a physical address was not successful. The invention may be extended beyond virtual machine monitors to other systems involving the software-based processing of instructions, and beyond multiprocessing systems to other systems involving concurrent access to virtual memory management data.

Abstract: A method and system are provided that does not perform a page walk on the guest page tables if the shadow page table entry corresponding to the guest virtual address for accessing the virtual memory indicates that a corresponding mapping from the guest virtual address to a guest physical address is not present in the guest page tables. A marker or indicator is stored in the shadow page table entries to indicate that a mapping corresponding to the guest virtual address of the shadow page table entry is not present in the guest page table.

Abstract: For a virtual memory of a virtualized computer system in which a virtual page is mapped to a guest physical page which is backed by a machine page and in which a shadow page table entry directly maps the virtual page to the machine page, reverse mappings of guest physical pages are optimized by removing the reverse mappings of certain immutable guest physical pages. An immutable guest physical memory page is identified, and existing reverse mappings corresponding to the immutable guest physical page are removed. New reverse mappings corresponding to the identified immutable guest physical page are no longer added.

Abstract: A virtualization platform provides fault tolerance for a primary virtual machine by continuously transmitting checkpoint information of the primary virtual machine to a collector process, such as a backup virtual machine. When implemented on a hardware platform comprising a multi-processor that supports nested page tables, the virtualization platform leverages the nested page table support to quickly identify memory pages that have been modified between checkpoints. The backup virtual machine provides feedback information to assist the virtualization platform in identifying candidate memory pages for transmitting actual modifications to the memory pages rather than the entire memory page as part of the checkpoint information. The virtualization platform further maintains a modification history data structure to identify memory pages that can be transmitted simultaneous with the execution of the primary virtual machine rather than while the primary virtual machine has been stunned.

Abstract: A virtualization platform provides fault tolerance for a primary virtual machine by continuously transmitting checkpoint information of the primary virtual machine to a collector process, such as a backup virtual machine. When implemented on a hardware platform comprising a multi-processor that supports nested page tables, the virtualization platform leverages the nested page table support to quickly identify memory pages that have been modified between checkpoints. The backup virtual machine provides feedback information to assist the virtualization platform in identifying candidate memory pages for transmitting actual modifications to the memory pages rather than the entire memory page as part of the checkpoint information. The virtualization platform further maintains a modification history data structure to identify memory pages that can be transmitted simultaneous with the execution of the primary virtual machine rather than while the primary virtual machine has been stunned.

Abstract: A virtualization platform provides fault tolerance for a primary virtual machine by continuously transmitting checkpoint information of the primary virtual machine to a collector process, such as a backup virtual machine. When implemented on a hardware platform comprising a multi-processor that supports nested page tables, the virtualization platform leverages the nested page table support to quickly identify memory pages that have been modified between checkpoints. The backup virtual machine provides feedback information to assist the virtualization platform in identifying candidate memory pages for transmitting actual modifications to the memory pages rather than the entire memory page as part of the checkpoint information. The virtualization platform further maintains a modification history data structure to identify memory pages that can be transmitted simultaneous with the execution of the primary virtual machine rather than while the primary virtual machine has been stunned.

Abstract: To generate a checkpoint for a virtual machine (VM), first, while the VM is still running, a copy-on-write (COW) disk file is created pointing to a parent disk file that the VM is using. Next, the VM is stopped, the VM' s memory is marked COW, the device state of the VM is saved to memory, the VM is switched to use the COW disk file, and the VM begins running again for substantially the remainder of the checkpoint generation. Next, the device state that was stored in memory and the unmodified VM memory pages are saved to a checkpoint file. Also, a copy may be made of the parent disk file for retention as part of the checkpoint, or the original parent disk file may be retained as part of the checkpoint. If a copy of the parent disk file was made, then the COW disk file may be committed to the original parent disk file.

Abstract: A method is provided for creating and maintaining the validity of a cache group including one or more cache elements. Each of the cache elements corresponds to a different address space in a virtual memory of a computer system. Each of the cache elements include one or more caches that store mappings from virtual addresses to data or values that are functions of or dependent upon physical addresses that correspond to the virtual addresses. When there is an address space switch from a first address space to a second address space, the cache group is searched to find the cache element corresponding to the second address space, and that found cache element is made the current cache element for virtual memory access through the cache element. Changes in the page tables are also detected and reflected in the caches of the cache group to maintain the caches up-to-date.

Abstract: In a computer system supporting execution of virtualization software and at least one instance of virtual system hardware, an interface is provided into the virtualization software to allow a program to directly define the access characteristics of its program data stored in physical memory. The technique includes providing data identifying memory pages and their access characteristics to the virtualization software which then derives the memory access characteristics from the specified data. Optionally, the program may also specify a pre-defined function to be performed upon the occurrence of a fault associated with access to an identified memory page. In this manner, programs operating both internal and external to the virtualization software can protect his memory pages, without intermediation by the operating system software.