WO2012163017A1

WO2012163017A1 - Method for processing access exception of distributed virtual machine and virtual machine monitor

Info

Publication number: WO2012163017A1
Application number: PCT/CN2011/081116
Authority: WO
Inventors: 邱军
Original assignee: 华为技术有限公司
Priority date: 2011-10-21
Filing date: 2011-10-21
Publication date: 2012-12-06
Also published as: CN102439567A

Abstract

Disclosed are a method for processing access exception of a distributed virtual machine and a virtual machine monitor, which relate to the technical field of computers and can reduce the occurrence of false sharing, thereby improving the performance of a memory of the distributed virtual machine. The method for processing access exception of a distributed virtual machine provided by the embodiment of the present invention comprises: finding a subpage where access exception occurs according to an address of a physical page where the access exception occurs when the virtual machine executes a current instruction and accesses a memory of the virtual machine; judging whether the virtual machine has the right to access the subpage where the access exception occurs; if the virtual machine does not have the access right, repairing the subpage where the access exception occurs, so that the memory of the virtual machine can access the subpage where the access exception occurs and re-execute the current instruction; and if the virtual machine has the access right, executing the current instruction, and returning an execution result to a virtual machine execution context, so that the virtual machine completes the execution of the current instruction.

Description

Distributed virtual machine access exception processing method and virtual machine monitor

The present invention relates to the field of computer technologies, and in particular, to a processing method for a distributed virtual machine access exception and a virtual machine monitor. Background technique

A virtual machine (VM) is a complete computer system that runs through a software and has a complete hardware system function and runs in a completely isolated environment. Distributed virtualization technology is a technology that reassembles resources from multiple physical machines into a virtual machine in a virtual way. When the operating system installed on the virtual machine runs and uses these virtual resources, it is deployed in each A distributed virtual machine monitor (D VMM) on a physical machine intercepts sensitive access behaviors to ensure the correct use of virtual resources by virtual machines.

Since the processor on each physical machine can only access local memory, DVMM needs to intercept the virtual machine's access to the local cache (cache) of remote memory or remote memory, and hand these access events to distributed shared memory ( Distributed Shared Memory (DSM) processing to maintain the correctness and consistency of local cache and remote memory ( Consistent and Coherent).

In general, DVMM capture processor access to remote memory or local cache requires the use of a processor's Page Fault (PF) or Nested Page Fault (Nested Page Fault) mechanisms, and these exceptions are physical Page size (for example, 4KB, 2MB, or 1 GB) is generated, that is, the processor accessing any data in this physical page will generate an exception, which leads to False Sharing. In the extreme case, the processor on two different physical nodes needs to access one byte of the same memory address. In order to maintain the memory of this byte, the DSM is consistent with the two processors, and the processor needs to intercept the memory address. Access, and because memory capture is in physical pages, causing the processor to Access to other bytes than the actual shared address in the physical page also creates a memory exception (no access) that causes the DSM to trigger processing to maintain shared memory consistency. False sharing reduces the cache utilization in DVMM, increases meaningless network communication, and increases remote memory access latency, which in turn affects distributed virtual machine memory performance.

Summary of the invention

The technical problem to be solved by the embodiments of the present invention is to provide a processing method for a distributed virtual machine access exception and a virtual machine monitor, which can reduce the generation of false sharing, thereby improving the performance of the distributed virtual machine memory.

To solve the above technical problem, the embodiment of the present invention uses the following technical solution: A method for processing a distributed virtual machine access exception includes:

Obtaining an access exception according to the in-page offset address according to the in-page offset address when the virtual machine executes the current instruction and accesses the virtual machine memory, and the physical page includes a plurality of subpages;

Determining whether the virtual machine has the access right of the sub-page with the access exception, and if the virtual machine does not have the access right of the sub-page with the access exception, repairing the sub-page with the access exception, and making the virtual machine The memory can access the subpage where the access exception occurs and re-execute the current instruction.

And if the virtual machine has the access right of the subpage having the access exception, executing the current instruction, and returning the execution result to the virtual machine execution context, so that the virtual machine completes execution of the current instruction.

A virtual machine monitor, including:

a sub-page search module, configured to obtain an in-page offset address of a sub-page of a physical page in which an access abnormality occurs according to an address of a physical page that accesses an abnormality when the virtual machine executes the current instruction and accesses the virtual machine memory, and according to the page Internal offset address, find a subpage where an access exception occurs, and the physical page includes several subpages; An access authority determining module, configured to determine whether the virtual machine has the access right of the subpage with the abnormal access,

a distributed shared memory, configured to determine, in the virtual machine, the access permission of the subpage that has the access exception, repair the subpage where the access exception occurs, and enable the virtual machine memory to access the subpage with the access exception And re-execute the current instruction,

An instruction emulation execution module, configured to: execute, by the virtual machine, an access permission of the subpage having the access exception, execute the current instruction, and return an execution result to a virtual machine execution context, so that the virtual machine completes The execution of the current instruction.

A distributed virtual machine includes a plurality of physical servers connected through a network, and each of the physical servers is provided with a virtual machine monitor, and the virtual machine monitor includes:

a sub-page search module, configured to obtain an in-page offset address of a sub-page of a physical page in which an access abnormality occurs according to an address of a physical page that accesses an abnormality when the virtual machine executes the current instruction and accesses the virtual machine memory, and according to the page Internal offset address, find a subpage where an access exception occurs, and the physical page includes several subpages;

An access authority determining module, configured to determine whether the virtual machine has the access permission of the subpage with the abnormal access,

An instruction emulation execution module, configured to: execute, by the virtual machine, an access permission of the subpage having the access exception, execute the current instruction, and return an execution result to a virtual machine execution context, so that the virtual machine completes The execution of the current instruction. The controller divides the physical page into several sub-pages, and when an access exception occurs on the physical page, other sub-pages other than the sub-page where the access abnormality occurs can be normally accessed, thereby reducing the occurrence of sharing. The virtual machine memory can access the subpage having the access exception; when determining the access authority of the subpage, simulating the execution of the current access exception instruction, and returning the execution result to the virtual machine execution context, so that the The virtual machine completes the execution of the current instruction, which can effectively solve the access exception problem and improve the performance of the virtual machine memory.

DRAWINGS

In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments will be briefly described below. It is obvious that the drawings in the following description are only the present invention. For some embodiments, other drawings may be obtained from those of ordinary skill in the art without departing from the drawings. Schematic diagram

2 is a schematic diagram of a virtual machine monitor according to an embodiment of the present invention;

3 is a schematic diagram of a command simulation execution module in an embodiment of the present invention;

DETAILED DESCRIPTION A pseudo-machine monitor can reduce the generation of false shares, thereby improving the performance of distributed virtual machine memory.

The embodiments of the present invention are described in detail below with reference to the accompanying drawings.

The first embodiment of the server comprises: a central processing unit (CPU), a virtual machine memory, a network card, and a high-speed input/output (I/O) device. In addition, each physical server is provided with a virtual machine monitor, and the virtual machine monitors communicate with each other, so that the processor of each physical server can access the resources of other physical servers, thereby forming a virtual Aggregated hardware platform.

The virtual machine memory is an isolated, zero-based and contiguous pseudo-physical memory space for the virtual machine. This memory space corresponds to a piece of physical memory allocated by each physical server. The virtual machine monitor establishes a distributed virtual machine on each physical server.

The P2M (Pseudo-physical Address to Machine Physical Address) table converts the GFN into an MFN. A part of the GFN in the P2M table is mapped to the memory of the local server; since the processor of the local physical server cannot directly access the memory of other physical servers, the GFN mapping mapping the memory of other physical servers is cached locally, and this cache stores the memory on the remote physical server. Content. In order to ensure the consistency of the local cache and remote memory, you need to set the distributed shared memory in the virtual machine monitor.

This embodiment provides a processing method for a distributed virtual machine access exception. As shown in FIG. 1, the method includes:

Step 101: An access address occurs when the virtual machine executes the current instruction and accesses the virtual machine memory, and finds a subpage with an access exception according to the in-page offset address, where the physical page includes several subpages.

When a processor on a physical server accesses data in the virtual machine's memory address,

The DSM needs to intercept this processor's access to this memory address. This embodiment divides the physical page into a number of sub-pages to reduce the intercept granularity and assign sub-page addresses to the sub-pages. Therefore, when an access exception occurs on a physical page, a subpage with an exception can be found, and other subpages other than the subpage where the access exception occurs in the physical page can be normally accessed, thereby greatly improving the efficiency of the memory. , reducing the phenomenon of false sharing.

Since the access to the memory address is in bytes, in order to find the subpage where the exception occurs, the in-page offset address of the subpage needs to be obtained. The in-page offset address refers to the address of the subpage relative to the physical page where it is located, that is, the difference between the subpage address and the start address of the physical page. Access The address of the abnormal physical page minus the starting address of the physical page is the offset address of the subpage where the exception occurred. Based on the calculated in-page offset address, you can find the subpage where the access exception occurred.

Step 102: Determine whether the virtual machine has the access right of the subpage where the access abnormality occurs.

After finding the subpage where the access exception occurs based on the in-page offset address of the subpage, it is judged whether or not the subpage has access authority. In order to facilitate the management of the sub-pages, the embodiment sets a sub-page management module in the virtual machine monitor for storing the permission information of the sub-pages, as shown in FIG. 2, wherein the physical page permissions are all sub-pages. Permissions for the least privileged subpage. In general, the permission information includes Read Write, Read Only, and Unreadable (INV), and the level of permissions decreases. Per-page permissions can be changed through distributed shared memory. The permissions information for a subpage is updated when the virtual machine monitor maintains shared memory consistency.

For example, if a processor needs to write to the virtual machine memory, after reading the contents of the subpage management module, it is found that the permission to access the abnormal subpage is readable and unwritable, that is, the processor cannot access the memory. The write operation is performed, so the processor at this time does not have access to this subpage.

Step 103: If the virtual machine does not have the access permission of the subpage that has an access exception, repair the subpage where the access exception occurs, enable the virtual machine memory to access the subpage with the access exception and re-execute the current instruction. .

After determining that the access permission of the abnormal subpage is not accessed, the virtual machine monitor calls the distributed shared memory to repair the subpage, so that the subpage can be accessed by the virtual machine memory, that is, the permission of the subpage is modified to be Read or writable. After the repair is completed, the virtual machine's processor re-executes the abnormal instruction. Since the virtual machine memory is readable or writable, the instruction can be executed smoothly, reducing the time for the virtual machine monitor to handle the exception.

Step 104: If the virtual machine has the access permission of the subpage that has an access exception, execute the current instruction, and return the execution result to the virtual machine execution context. The virtual machine completes execution of the current instruction.

The context is a static description of the whole process of the process execution activity. Usually, the contents of the executed process instructions and data in the relevant registers and the stack are referred to as the above, and the contents of the executed instructions and data in the registers and the stack are called The text, the contents of the instructions and data to be executed in the register and the stack are referred to below. The virtual machine execution context in this embodiment includes virtual machine registers, content in virtual machine memory, and virtual machine control information.

After determining that the virtual machine has access rights to access the abnormal subpage, the virtual machine monitor further executes the current instruction, and returns the execution result to the virtual machine execution context, so that the virtual machine completes execution of the current instruction, the virtual machine After receiving the instruction simulation result, execute the next instruction of the current instruction.

The process of the virtual machine monitor emulating the instruction to execute the current access exception is as follows:

The virtual machine memory saves the original execution result of the current instruction;

According to the instruction set encoding, the current instruction is decoded to obtain the instruction operation code and the operand; according to the instruction operation code, the corresponding operation is performed on the operand, and after the operation is successful, a new execution result is obtained, and the operand related to the current instruction is obtained. Update to the virtual machine execution context.

After completing the above steps, the process returns from the virtual machine monitor to the virtual machine and updates the execution results saved in the execution context of the virtual machine. Through the above method, the virtual machine monitor can replace the virtual machine to process the abnormal access instruction, and can quickly repair the abnormal virtual machine memory, thereby improving the efficiency of the virtual machine memory.

During the simulation of executing the current instruction, you may encounter the case where the operand is not in the subpage where the exception is currently accessed, but in other subpages, therefore, the virtual machine monitor first needs to read the operand from other subpages. . Therefore, after determining that the access authority has a subpage, the embodiment further includes the following steps;

Step 105: Determine whether there is an access right of the memory operand of the current instruction, and step 106, if there is no access right of the memory operand of the current instruction, repair the subpage where the memory operand is located, so that the Memory operands can be accessed. After repairing the subpage where the memory operand is located, the virtual machine monitor can execute the current access exception instruction.

In the processing method of the distributed virtual machine access exception of the embodiment, when the physical page is divided into a plurality of sub-pages, when an access abnormality occurs on the physical page, other sub-pages other than the sub-page where the access abnormality occurs can be normally accessed, thereby reducing The occurrence of the fake share occurs, and when it is determined that the access permission of the subpage accessing the exception does not occur, the subpage having the access exception is repaired, so that the subpage can be accessed by the virtual machine memory; the subpage having the access exception is judged When the access authority is executed, the current instruction is executed, and the execution result is returned to the virtual machine execution context, so that the virtual machine completes execution of the current instruction, which can effectively solve the access exception and improve the performance of the virtual machine memory. Embodiment 2

The embodiment provides a virtual machine monitoring machine, as shown in FIG. 2, including: a subpage search module 1 1 , an access authority judging module 12, a distributed shared memory 13 and an instruction emulation execution module 14 , wherein

The sub-page search module 1 1 is configured to obtain an intra-page offset address of a sub-page of the physical page where the access abnormality occurs, according to the address of the physical page where the abnormality occurs when the virtual machine executes the current instruction and accesses the virtual machine memory, and according to the Describe an in-page offset address, find a subpage where an access exception occurs, and the physical page includes a plurality of subpages;

The access authority judging module 12 is configured to determine whether the virtual machine has the access right of the sub-page with the abnormal access;

The distributed shared memory 13 is configured to: when determining that the virtual machine does not have the access permission of the subpage that has the access exception, repair the subpage where the access exception occurs, so that the virtual machine memory can access the subpage with the access exception and Re-execute the current instruction;

The instruction simulation execution module 14 is configured to: when determining that the virtual machine has the access authority of the subpage having the access exception, execute the current instruction, and return the execution result to the virtual machine execution context, so that the virtual machine completes the Execution of the current instruction. The virtual machine execution context in this embodiment includes a virtual machine register, a content in a virtual machine memory, and a virtual machine control letter. Interest.

Further, the access authority determining module 12 is further configured to: determine whether the access authority of the memory operand of the current instruction is available;

The distributed shared memory 13 is further configured to: when determining that there is no access permission of the memory operand, repair a subpage where the memory operand is located, so that the memory operand can be accessed.

The virtual machine monitoring machine of this embodiment further includes a subpage management module 10 for storing permission information of the subpage.

Further, the access authority determining module 12 is further configured to read the permission information of the subpage in the subpage management module, and the access authority of the physical page is not greater than the access authority of the subpage included in the subpage.

The rights information includes: readable and writable, readable and writable, and unreadable and unwritable. As shown in FIG. 3, the instruction emulation execution module 14 of this embodiment specifically includes: a decoding unit 141, configured to decode the current instruction according to the instruction set encoding, to obtain an instruction opcode and an operand;

The executing unit 142 is configured to perform a corresponding operation on the operand according to the instruction opcode. After the operation is successful, the execution result is obtained, and the operand related to the current instruction is updated to the virtual machine execution context.

The working principle of each part of the virtual machine monitoring machine of this embodiment is similar to that of the first embodiment, and details are not described herein again.

In the virtual machine monitoring machine of this embodiment, when the physical page is divided into a plurality of sub-pages, when an access abnormality occurs on the physical page, other sub-pages other than the sub-page where the access abnormality occurs can be normally accessed, thereby reducing the occurrence of the false sharing. And through the access authority judgment module, when determining that the virtual machine does not have access rights to access the abnormal subpage, the distributed shared memory repairs the subpage that accesses the exception, so that the subpage with the access exception is allowed to be accessed by the virtual machine memory; When judging the access permission of a subpage with an access exception, the instruction emulation execution module executes the current instruction, and the execution result is executed. Returning to the virtual machine execution context, enabling the virtual machine to complete the execution of the current instruction, effectively solving the access exception and improving the performance of the virtual machine memory.

Embodiment 3

The embodiment provides a distributed virtual machine. As shown in FIG. 4, the system includes a plurality of physical servers connected through a network. Each of the physical servers is provided with a virtual machine monitor. The virtual machine monitor includes:

The instruction simulation execution module 14 is configured to: when determining that the virtual machine has the access authority of the subpage having the access exception, execute the current instruction, and return the execution result to the virtual machine execution context, so that the virtual machine completes the Execution of the current instruction. The virtual machine execution context in this embodiment includes virtual machine registers, content in virtual machine memory, and virtual machine control information.

Further, the virtual machine monitor of this embodiment further includes:

a subpage management module 10, configured to store permission information of the subpage;

The communication module 15 is configured to implement communication between the virtual machine monitors in the distributed virtual machine to ensure consistency of information in the same memory address on different physical servers.

The working principle of each part of the virtual machine monitoring machine of this embodiment is similar to that of the first embodiment, and is no longer The distributed virtual machine in this embodiment divides the physical page into a plurality of sub-pages, and when an access abnormality occurs on the physical page, the other sub-pages other than the sub-page where the access abnormality occurs can be normally accessed, thereby reducing the occurrence of the false sharing. And, through the access authority judgment module of the virtual machine monitor, when the virtual machine does not have the access right of the access subpage of the abnormality, the distributed shared memory repairs the subpage that accesses the abnormality, so that the subpage that has the access abnormality is allowed to be virtualized. Machine memory access; when determining the access permission of the subpage having the access exception, the instruction emulation execution module executes the current instruction, and returns the execution result to the virtual machine execution context, so that the virtual machine completes the execution of the current instruction, which can be effective Resolve access exceptions and improve the performance of virtual machine memory.

Through the description of the above embodiments, those skilled in the art can clearly understand that the present invention can be implemented by means of software plus necessary general hardware, and of course, by hardware, but in many cases, the former is a better implementation. . Based on such understanding, the technical solution of the present invention, which is essential or contributes to the prior art, may be embodied in the form of a software product stored in a readable storage medium, such as a floppy disk of a computer. A hard disk or optical disk or the like includes instructions for causing a computer device (which may be a personal computer, a server, or a network device, etc.) to perform the methods described in various embodiments of the present invention.

The above is only the specific embodiment of the present invention, but the scope of the present invention is not limited thereto, and any person skilled in the art can easily think of changes or substitutions within the technical scope of the present invention. It should be covered by the scope of the present invention. Therefore, the scope of the invention should be determined by the scope of the appended claims.

Claims

Claim

A processing method for a distributed virtual machine access abnormality, comprising: obtaining an access abnormality occurrence sub-page by an offset address within a physical description page of an access abnormality when the virtual machine executes the current instruction and accesses the virtual machine memory; a page, the physical page includes a plurality of sub-pages; determining whether the virtual machine has the access right of the sub-page in which the access abnormality occurs, and if the virtual machine does not have the access right of the sub-page where the access abnormality occurs, the repairing station Describe the subpage where the access exception occurs, enabling the virtual machine memory to access the subpage where the access exception occurs and re-execute the current instruction.

The method for processing a distributed virtual machine access exception according to claim 1, further comprising: after determining that the virtual machine has the access authority of the subpage having the access exception;

Determining whether there is access permission of the memory operand of the current instruction,

If there is no access permission for the memory operand of the current instruction, the subpage where the memory operand is located is repaired, so that the memory operand can be accessed.

The method for processing a distributed virtual machine access exception according to claim 1, wherein after the finding a subpage having an access abnormality, determining whether the virtual machine has the subpage having the access abnormality Before access, it also includes:

The permission information of the subpage in which the access exception occurs is read, and the access authority of the physical page is not greater than the access authority of the subpage included.

The method for processing a distributed virtual machine access exception according to claim 3, wherein the rights information comprises: readable and writable, readable and writable, and unreadable and writable.

The method for processing a distributed virtual machine access exception according to claim 1, wherein the executing the current instruction comprises:

Decoding according to the instruction set encoding the current instruction, obtaining the instruction operation code and the operand; performing corresponding operations on the operand according to the instruction operation code, after the operation is successful, obtaining the execution result, and the operand related to the current instruction Update to the virtual machine execution context.

The method for processing a distributed virtual machine access exception according to claim 1 or 5, wherein the virtual machine execution context includes a virtual machine register, content in a virtual machine memory, and virtual machine control information.

7. A virtual machine monitor, comprising:

An access authority determining module, configured to determine whether the virtual machine has the access permission of the subpage having the abnormal access,

8. The virtual machine monitor of claim 7 wherein:

The access authority determining module is further configured to: determine whether the access authority of the memory operand of the current instruction is

If there is no access permission of the memory operand of the current instruction, the subpage where the memory operand is located is repaired, so that the memory operand can be accessed.

The virtual machine monitor according to claim 7, further comprising: a subpage management module, configured to store the permission information of the subpage.

10. The virtual machine monitor of claim 9 wherein:

The access authority determining module is further configured to read the permission information of the subpage in the subpage management module, and the access authority of the physical page is not greater than the access authority of the subpage included by the subpage.

The virtual machine monitor according to claim 9 or 10, wherein the rights information comprises: readable and writable, readable and writable, and unreadable and unwritable.

The virtual machine monitor according to claim 7, wherein the command simulation execution module specifically includes:

a decoding unit, configured to decode the current instruction according to the instruction set encoding, to obtain an instruction operation code and an operand;

The execution unit is configured to perform a corresponding operation on the operand according to the instruction operation code. After the operation succeeds, the execution result is obtained, and the operand related to the current instruction is updated to the virtual machine execution context.

13. The virtual machine monitor of claim 7 or 12, wherein the virtual machine execution context comprises a virtual machine register, content in a virtual machine memory, and virtual machine control information.

A distributed virtual machine, comprising a plurality of physical servers connected through a network, each of which has a virtual machine monitor, wherein the virtual machine monitor comprises:

An access authority determining module, configured to determine whether the virtual machine has the access right of the subpage with the abnormal access, a distributed shared memory, configured to determine, in the virtual machine, the access permission of the subpage that has the access exception, repair the subpage where the access exception occurs, and enable the virtual machine memory to access the subpage with the access exception And re-execute the current instruction,

The distributed virtual machine according to claim 14, wherein the virtual machine monitor further comprises:

The communication module is configured to implement communication between the virtual machine monitors in the distributed virtual machine to ensure consistency of information in the same memory address on different physical servers.