Patent Application
20130117530
This application claims priority to Korean Patent Application No. 10-2011-0115357 filed on Nov. 7, 2011 in the Korean Intellectual Property Office (KIPO), the entire contents of which are hereby incorporated by reference.
1. Technical Field
Example embodiments of the present invention relate in general to virtualization technology, and more specifically, to an apparatus for translating a virtual address space which can quickly translate a virtual address space between a virtual machine monitor and a guest operating system, or between a guest operating system and a host operating system, to facilitate access to the guest operating system during execution of the virtual machine monitor.
2. Related Art
In virtual machine environments, a plurality of virtual machines may be implemented on one actual machine, and an operating system may run on each virtual machine. A virtual machine monitor, which may be implemented in software, monitors instructions executed by a guest operating system running on the virtual machine.
The virtual machine monitor allows the guest operating system to execute instructions such as CPU register operation, etc. among instructions executed by the guest operating system, and does not allow the guest operating system to execute virtualization-sensitive instructions such as a change in the setting of a memory management unit, an enable/disable setting, etc., and directly execute virtualization-sensitive instructions instead of the guest operating system. The virtual machine monitor allows the guest operating system to recognize virtualization-sensitive instructions as being executed on the virtual machine which provides a virtualization environment to the guest operating system.
In order for the virtual machine monitor to execute virtual-sensitive instructions, a virtual address space is required to be translated from the guest operating system to the virtual machine monitor, the virtual machine monitor accesses instructions and data of the guest operating system to perform tasks, and then the virtual address space is required to be translated back to the guest operating system.
For para-virtualization, the source code of the guest operating system is modified to install the virtual machine monitor in a portion of the virtual address space of the guest operating system, so that the virtual address space need not be translated between the virtual machine monitor and the guest operating system. For full-virtualization, however, the virtual address space is frequently translated between the virtual machine monitor and the guest operating system in order for the virtual machine monitor to process the virtualization-sensitive instructions of the guest operating system.
However, in conventional full-virtualization technique, only a method using a shared area is used to translate the virtual address space between the virtual machine and the guest operating system.
In a case where the virtual machine monitor translates the virtual address space between the virtual machine monitor and the guest operating system, there are problems in that the virtual address space of the guest operating system should be applied to a page table of the virtual machine monitor whenever the virtual address space is changed, and thus the task of applying the virtual address space of the guest operating system to the page table of the virtual machine monitor deteriorates performance of the virtual machine and increases the amount of used memory.
Accordingly, example embodiments of the present invention are provided to substantially obviate one or more problems due to limitations and disadvantages of the related art.
Example embodiments of the present invention provide an apparatus for effectively translating the virtual address space between the virtual machine monitor and the guest operating system by arranging and translating the virtual address space on the basis of characteristics of a memory management unit.
The object of the present invention is not limited to the aforesaid, but other objects not described herein will be clearly understood by those skilled in the art from descriptions below.
In some example embodiments, an apparatus for translating a virtual address space includes: a virtual address space generation unit generating a virtual address space of a guest operating system, the guest operating system being executed in the virtual address space, and a virtual address space of a virtual machine monitor, the virtual machine monitor being executed in the virtual address space; a gateway page generation unit generating a gateway page allocated to a predetermined region of an actual memory region and mapped to the virtual address space of the guest operating system and the virtual address space of the virtual machine monitor; and a memory management unit executing the gateway page to map a kernel region of the guest operating system to the predetermined region of the virtual address space of the virtual machine monitor to perform translation between the virtual address space of the guest operating system and the virtual address space of the virtual machine monitor.
Example embodiments of the present invention will become more apparent by describing in detail example embodiments of the present invention with reference to the accompanying drawings, in which:
While the invention can be modified in various ways and take on various alternative forms, specific embodiments thereof are shown in the drawings and described in detail below as examples. There is no intent to limit the invention to the particular forms disclosed. On the contrary, the invention is to cover all modifications, equivalents, and alternatives falling within the spirit and scope of the appended claims. Elements of the example embodiments are consistently denoted by the same reference numerals throughout the drawings and detailed description.
It will be understood that, although the terms first, second, A, B, etc. may be used herein in reference to elements of the invention, such elements should not be construed as limited by these terms. For example, a first element could be termed a second element, and a second element could be termed a first element, without departing from the scope of the present invention. Herein, the term “and/or” includes any and all combinations of one or more referents.
It will be understood that when an element is referred to as being “connected” or “coupled” to another element, it can be directly connected or coupled to the other element or intervening elements may be present. In contrast, when an element is referred to as being “directly connected” or “directly coupled” to another element, there are no intervening elements present.
The terminology used herein to describe embodiments of the invention is not intended to limit the scope of the invention. The articles “a,” “an,” and “the” are singular in that they have a single referent, however the use of the singular form in the present document should not preclude the presence of more than one referent. In other words, elements of the invention referred to in the singular may number one or more, unless the context clearly indicates otherwise. It will be further understood that the terms “comprises,” “comprising,” “includes,” and/or “including,” when used herein, specify the presence of stated features, items, steps, operations, elements, and/or components, but do not preclude the presence or addition of one or more other features, items, steps, operations, elements, components, and/or groups thereof.
Unless otherwise defined, all terms (including technical and scientific terms) used herein are to be interpreted as is customary in the art to which this invention belongs. It will be further understood that terms in common usage should also be interpreted as is customary in the relevant art and not in an idealized or overly formal sense unless expressly so defined herein.
Hereinafter, in the embodiments of the present invention, apparatus and method for translating virtual address space may be implemented on a processor including a memory management unit. In particular, the processor including the memory management unit may be an ARM processor, but it is not limited thereto.
An apparatus for translating a virtual address space according to an embodiment of the present invention may include: a virtual address space generation unit generating a virtual address space of a guest operating system, the guest operating system being executed in the virtual address space, and a virtual address space of a virtual machine monitor, the virtual machine monitor being executed in the virtual address space; a gateway page generation unit generating a gateway page allocated to a predetermined region of an actual memory region and mapped to the virtual address space of the guest operating system and the virtual address space of the virtual machine monitor; and a memory management unit executing the gateway page to map a kernel region of the guest operating system to the predetermined region of the virtual address space of the virtual machine monitor to perform translation between the virtual address space of the guest operating system and the virtual address space of the virtual machine monitor.
Also an apparatus for translating a virtual address space according to an embodiment of the present invention may include: a virtual address space generation unit generating a virtual address space of a guest operating system, the guest operating system being executed in the virtual address space, and a virtual address space of a host operating system, the host operating system being executed in the virtual address space; a gateway page generation unit generating a gateway page allocated to a predetermined region of an actual memory region and mapped to the virtual address space of the guest operating system and the virtual address space of the host operating system; and a memory management unit executing the gateway page to map a guest operating system user region of the guest operating system to the predetermined region of the virtual address space of the host operating system to perform translation between the virtual address space of the guest operating system and the virtual address space of the host operating system.
Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.
Referring to
The hardware 110 may be a computer device such as a personal computer, a mobile computer device, etc. and a computing platform for running the guest operating system or the virtual machine monitor, which may include a central processing unit (CPU) executing an operation according to instructions provided to the guest operating system or virtual machine monitor, a memory management unit (MMU) performing translation between a virtual address provided from the CPU and a physical address of an actual memory region, and a memory corresponding to the actual memory region.
The MMU may include a translation table base register TTBR storing an address stored in a page table for connecting the virtual address space with the actual memory region, and a translation table base control register TTBCR determining operation of the TTBR. The memory may be a variety of media for storing data such as a hard disk, a floppy disk, a random access memory (RAM), a read only memory (ROM), and a flash memory.
The virtual machine monitor 120 may be executed on the hardware 110. The virtual machine monitor 120 may execute a virtual machine 130 which is an environment running the guest operating system. The virtual machine monitor 120 may be implemented in software, firmware, etc., and executed on other virtual machine monitors.
Also, the virtual machine monitor 120 may execute the virtual machine 130, and control the hardware in order to protect the virtual machine monitor 120 from the virtual machine 130.
Furthermore, the virtual machine monitor 120 performs translation between a virtual address space of the guest operating system and a virtual address space of the virtual machine monitor in order to process an interrupt occurring in the guest operating system, an exception for executing an undefined instruction, an instruction for performing an authority-required function of the operating system, for example, a virtualization-sensitive instruction such as a setting change of the MMU, an enable/disable of the interrupt, etc.
The virtual machine 130 may run an operating system such as the guest operating system 131, and execute the application 132, which may operate as a separate platform.
The guest operating system 131 may run on the virtual machine 130, execute the application 132, and access the hardware 110 to perform a variety of controls.
Referring to
The gateway page region 1100 may be mapped to a gateway page region of an actual memory region 3000.
The guest operating system kernel region 1300 is a core region for controlling and scheduling the guest operating system, which may be a region storing kernel code and data of the guest operating system.
The virtual machine monitor 120 may be arranged in a virtual address space separate from the virtual address space 1000 of the guest operating system which is the virtual address space of the virtual machine 130 running the guest operating system 131.
The virtual address space 2000 of the virtual machine monitor 120 may include a gateway page region 1100, a virtual machine monitor region 1200-1, and a guest operating system kernel region 1300.
The gateway page region 1100 of the virtual address space 1000 of the guest operating system and the gateway page region 1100 of the virtual address space 2000 of the virtual machine monitor may share a gateway page stored in a gateway page region which is a predetermined region of an actual memory region 3000.
The guest operating system kernel region 1300 of the virtual address space 1000 of the guest operating system and the guest operating system kernel region 1300 of the virtual address space 2000 of the virtual machine monitor may be mapped to a guest operating system kernel region 3300 which is a predetermined region of the actual memory region.
Referring to
Furthermore, the gateway page 1100 is a shared memory page which is mapped to all virtual address space regions such as the virtual address space 1000 of the guest operating system, the virtual address space 2000 of the virtual machine monitor, etc. by the virtual machine monitor 120, and may include an exception vector table 1110 and an address space translation code 1120.
The exception vector table 1110 may be a mapping table for replacing an interrupt occurring in the guest operating system, an exception for executing an undefined instruction, an instruction for performing an authority-required function of the operating system, for example, a virtualization-sensitive instruction such as a setting change of the MMU, an enable/disable of the interrupt, etc. among instructions executed by the guest operating system 131, with predetermined instructions corresponding to the virtualization-sensitive instruction.
The address space translation code 1129 may be an information code for performing translation between the virtual address space 1000 of the guest operating system and the virtual address space 2000 of the virtual machine monitor, where the virtual address of the guest operating system and the virtual address of the virtual machine monitor are mapped, or a page translation code which is an information code where the virtual address of the guest operating system and the virtual address of the host operating system are mapped.
For example, a region of all the virtual address spaces where the gateway page is mapped may be a 0 to 4 KB region. The 0 to 4 KB region of the virtual address space 1000 of the guest operating system may be set to necessarily map the gateway page 1100 to a region which is not mapped with the actual memory region 3000 for null pointer exception processing.
Referring to
For example, when the virtualization-sensitive instruction, the interrupt, the exception, etc. are detected during execution of the guest operating system, control is moved from the guest operating system 131 to the gateway page 1100 ({circle around (1)}, {circle around (2)}).
A first translation table base register TTBR0 and a second translation table base register TTBR1 of the memory management unit MMU, which stores an address of the page table for connecting the virtual address space and the actual memory region, store a page table address of the currently running guest operating system, and a translation table base control register TTBCR of the memory management unit is disabled.
Translation of the virtual address space may be performed by translating the page table address of the guest operating system stored in the first translation table base register TTBR0 to the page table address of the virtual machine monitor, and enabling the translation table base control register TTBCR (S120).
When the first translation table base register TTBR0 is translated to the page table address of the virtual machine monitor and the translation table base control register TTBCR is enabled, the virtual address space of the virtual machine monitor may be generated as shown with a dotted line of
Specifically, the virtual machine monitor region 1200-1 of the virtual address space, for example, a 0 to 2 GB region, may be a region for execution code and data of the virtual machine monitor. The kernel region of the guest operating system, for example, a 2 to 4 GB region, may be a region for access to the virtual address space of the guest operating system.
That is, the kernel region 1300 of the guest operating system, for example, the 2 to 4 GB region, may be generated the same as the guest operating system by using the untranslated page table address of the guest operating system stored in the first translation table base register TTBR0 and the page table address stored in the second translation table base register TTBR1.
Accordingly, after the virtual address space is translated to the virtual address space of the virtual machine monitor, the virtual machine monitor may access an address N of the virtual address space 2000 of the virtual machine monitor to perform a desired task, instead of accessing an address N of the virtual address space 2000 of the virtual machine monitor, and then instantly apply the results of the performed task to the guest operating system as if the task were performed on the virtual address space 1000 of the guest operating system.
When the virtual address space is translated to the virtual address space 2000 of the virtual machine monitor and then the virtual monitor is executed, the virtual monitor cannot access the user region in the virtual address space 1000 of the guest operating system, for example, the 0 to 2 GB region.
However, the user region of the guest operating system does not have instructions and data to be executed by the virtual machine monitor, and thus the virtual machine monitor does not need to access the region and may access the kernel region 1300 of the guest operating system to control the instructions.
When the execution of the virtual machine monitor is completed, control is moved from the virtual machine monitor to the gateway page ({circle around (4)}, {circle around (5)}). In order to perform translation from the virtual address space 2000 of the virtual machine monitor to the virtual address space 1000 of the gate operating system, the page table address of the virtual machine monitor stored in the first translation table base register TTBR0 of the memory management unit is returned to the page table address of the guest operating system, and the translation table base control register TTBCR of the memory management unit is disabled. Thus, translation({circle around (6)}) to the virtual address space 1000 of the guest operating system may be performed (S140).
In this case, all the virtual address spaces 1100, 1200, and 1300 of the guest operating system are presented, and the guest operating system may execute an instruction again in the virtual address space selected by the virtual machine monitor.
Referring to
First, the virtual machine monitor may fall into two types according to criteria such as execution layer, execution order, etc. of the virtual machine monitor.
As the guest operating system controls an application, so the type-1 virtual machine monitor, which is referred to as a native VMM, may directly access the hardware. The guest operating system may be a virtual machine monitor executed on the hardware in the second level. The type-1 virtual machine monitor may be, for example, CP/CMS developed at IBM, z/VM, Xen, etc.
The type-2 virtual machine monitor, which is referred to as a host VMM, may be executed on the guest operating system like an application. The guest operating system may be a virtual machine monitor executed on the hardware in the third level. The type-2 virtual machine monitor may be, for example, VMware Sever, VMware Workstation, virtual PC developed at MS.
In order for the type-2 virtual machine monitor to be applied to translate the virtual address space between the host operating system and the guest operating system, as shown in
The virtual address space 1000 of the guest operating system may include the gateway page region 1100, a guest operating system user region 1200, and a guest operating system kernel region 1300.
Also, the gateway page region 1100 of the host operating system and the gateway page region 1100 of the guest operating system may be mapped to the gateway page region 3100 of the actual memory region. The gate operating system kernel region 1300 of the guest operating system may be mapped to the kernel region 3300 of the guest operating system of the actual memory region.
A gateway page is mapped to the gateway page region 1100 allocated to the host operating system kernel region 1300 of the virtual address space 2000-1 of the host operating system. The gateway page may include a page translation code for page translation between the virtual address space 2000-1 of the host operating system and the virtual address space 1000 of the guest operating system.
Also, the gateway page may be mapped to the gateway page region 1100 of the guest operating system, for example, a 0 to 4 KB region of the virtual address space 1000 of the guest operating system. The 0 to 4 KB region is a virtual address space which is not used by most of the guest operating systems, and the guest operating system cannot access the gateway page region 1100.
In order to translate the virtual address space between the virtual address space 2000-1 of the host operating system and the virtual address space 1000 of the guest operating system when the virtual address of the gateway page region 1100 allocated to the virtual address space 2000-1 of the host operating system is different from the virtual address of the gateway page region 1100 allocated to the virtual address space 1000 of the guest operating system, the host operating system may have control when a virtual address space currently used by the host operating system is the virtual address space of the host operating system, the first translation table base register TTBR0 and the second translation table base register TTBR1 of the memory management unit may store a page table address of the host operating system, and the translation table base control register TTBCR may be set to be disabled (S2).
In order to translate the virtual address space 1000 of the guest operating system, by changing a page table address of the host operating system stored in the first translation table base register TTBR0 of the memory management unit to the page table address of the guest operating system, keeping the page table address of the host operating system stored in the second translation table base register TTBR1 of the memory management unit, enabling the translation table base register TTBCR of the memory management unit, and moving control from the host operating system to the gateway page, as shown in
As shown in
Referring to
In this case, since the virtual machine monitor region 1200-1 of the virtual address space 2000 of the virtual machine monitor, which stores code and data of the virtual machine monitor, is fixed, but the virtual address space of the guest operating system may be arbitrarily changed, the virtual machine monitor may apply to the page table the virtual address space of each guest operating system obtained by tracking the virtual address space of the guest operating system which is a monitoring target depicted as a dotted line.
Accordingly, when the apparatus for translating virtual address according to an embodiment of the present invention is used as described above, the virtual machine monitor can improve performance of the virtual machine monitor using the page table of the guest operating system again without keeping information of a separate page table for translation between the virtual address space of the virtual machine monitor and the virtual address space of the guest operating system.
The apparatus for translating the virtual address space according to the present invention can map a gateway page allocated to an actual memory area to the virtual address space of the guest operating system and the virtual address space of the virtual machine monitor, and map a kernel area of the guest operating system to the virtual address space of the virtual machine monitor. Thus, the apparatus does not need to map the virtual address space of the guest operating system to the page table of the virtual machine monitor, thereby enhancing performance of the virtual machine and reducing the amount of used memory.
Furthermore, the apparatus can translate the virtual address space using the gateway page and the memory management unit and thus translate the virtual address space with short code, thereby shortening development time of the virtual machine monitor, enhancing stability of the virtual machine monitor, and reducing time consumed for translation of the virtual address space.
It will be apparent to those skilled in the art that various modifications and variations can be made in the present invention. Thus, it is intended that the present invention covers the modifications and variations of this invention provided they come within the scope of the appended claims and their equivalents.
| Number | Date | Country | Kind |
|---|---|---|---|
| 10-2011-0115357 | Nov 2011 | KR | national |
