Method for efficient virtualization of physical memory in a virtual-machine monitor
View Patent ↗Various embodiments of the present invention are directed to efficient provision, by a virtual-machine monitor, of a virtual, physical memory interface to guest operating systems and other programs and routines interfacing to a computer system through a virtual-machine interface. In one embodiment of the present invention, a virtual-machine monitor maintains control over a translation lookaside buffer (“TLB”), machine registers which control virtual memory translations, and a processor page table, providing each concurrently executing guest operating system with a guest-processor-page table and guest-physical memory-to-physical memory translations. In one embodiment, a virtual-machine monitor can rely on hardware virtual-address-translation mechanisms for the bulk of virtual-address translations needed during guest-operating-system execution, thus providing a guest-physical memory interface without introducing excessive overhead and inefficiency.
1. A method for virtualizing physical memory and virtual-address translation by a virtual-machine monitor, the method comprising:
providing a guest-processor-page table employed by a guest operating system; and
resolving a translation-lookaside-buffer-miss fault by
first seeking a virtual-address translation in a virtual-monitor-maintained host virtual-hash-page table, and
when a virtual-address translation cannot be found in the host virtual-hash-page table,
seeking a virtual-address translation in the guest-processor-page table to find the virtual-address translation, and, if a virtual-address translation cannot be found in the guest-processor-page table, passing the translation-lookaside-buffer-miss fault to the guest operating system.
2. The method of claim 1 wherein virtual-address translations stored in the translation-lookaside-buffer and virtual-monitor-maintained virtual-hash-page table both contain host physical memory addresses.
3. The method of claim 1 wherein virtual-address translations stored in the guest-processor-page table contain guest-physical memory addresses.
4. The method of claim 1 further including, following passing of the translation-lookaside-buffer-miss fault to the guest operating system:
resolving the translation-lookaside-buffer-miss fault by the guest operating system to produce a guest-physical memory address;
inserting a virtual-address translation into the guest-processor-page table by the guest operating system that includes a guest-physical memory address; and
intercepting insertion of the virtual-address translation into the translation-lookaside buffer by the virtual-machine monitor, which replaces the guest-physical address in the virtual-address translation with a physical memory address and placing the virtual-address translation into the virtual-monitor-maintained virtual-hash-page table and the translation-lookaside-buffer.
5. Computer-readable instructions encoded in a computer-readable memory or stored on a computer-readable data-storage device that implement a method, for virtualizing physical memory and virtual-address translation by a virtual-machine monitor, by:
providing a guest-processor-page table employed by a guest operating system; and
resolving a translation-lookaside-buffer-miss fault by
first seeking a virtual-address translation in a virtual-monitor-maintained host virtual-hash-page table, and
when a virtual-address translation cannot be found in the host virtual-hash-page table,
seeking a virtual-address translation in the guest-processor-page table to find the virtual-address translation, and, if a virtual-address translation cannot be found in the guest-processor-page table, passing the translation-lookaside-buffer-miss fault to the guest operating system.
6. A virtual-machine monitor that virtualizes physical memory and virtual-address translation by:
providing a guest-processor-page table employed by a guest operating system; and
resolving a translation-lookaside-buffer-miss fault by
first seeking a virtual-address translation in a virtual-monitor-maintained host virtual-hash-page table, and
when a virtual-address translation cannot be found in the host virtual-hash-page table,
seeking a virtual-address translation in the guest-processor-page table to find the virtual-address translation, and, if a virtual-address translation cannot be found in the guest-processor-page table, passing the translation-lookaside-buffer-miss fault to the guest operating system.