Processor mode for limiting the operation of guest software running on a virtual machine supported by a virtual machine monitor

• US 7,818,808 B1
• Filed: 12/27/2000
• Issued: 10/19/2010
• Est. Priority Date: 12/27/2000
• Status: Expired due to Fees

• Current Assignee: Intel Corporation
• Original Assignee: Intel Corporation
• Inventors: Chou, Stephen, Kozuch, Michael, Neiger, Gilbert, Uhlig, Richard, Jeyasingh, Stalinselvaraj, Kagi, Alain, Cota-Robles, Erik
• Primary Examiner(s): PYZOCHA, MICHAEL J
• Application Number:
  US09/752,134
• Time in Patent Office: 3,583 Days
• Field of Search: 713/200, 726/26, 718/1, 711/6, 703/27
• US Class Current: 726/26
• CPC Class Codes: G06F 12/145 the protection being virtual, e.g. for virtual blocks or segments before a translation mechanism
• CPC Class Codes: G06F 2009/45583 Memory management, e.g. access or allocation
• CPC Class Codes: G06F 9/45558 Hypervisor-specific management and integration aspects

Abstract

In one embodiment, a processor mode is provided for guest software. The processor mode enables the guest software to operate at a privilege level intended by the guest software. When the guest software attempts to perform an operation restricted by the processor mode, the processor mode is exited to transfer control over the operation to a virtual-machine monitor, which runs outside this processor mode.

Claims

1. A method comprising:

running guest software in a processor mode that enables the guest software to operate at a privilege level intended by the guest software;

identifying, within said processor mode, an attempt of the guest software to perform an operation restricted by said processor mode;

determining, within said processor mode, whether the attempt of the guest software would fail if the guest software was running outside said processor mode;

allowing the guest software to attempt the operation within said processor mode in response to determining that the attempt would fail if the guest software was running outside said processor mode;

transferring control over the operation to an operating system running within said processor mode in response to the guest software attempting the operation; and

generating a virtualization trap in response to determining that the attempt would succeed if the guest software was running outside said processor mode.

2. The method of claim 1 wherein determining that the attempt of the guest software would fail includes determining that the guest software is running with insufficient privilege to perform the operation.

3. The method of claim 1 further comprising exiting said processor mode to transfer control over the operation to a virtual machine monitor running outside said processor mode in response to determining that the attempt would succeed if the guest software was running outside said processor mode.

4. A processor comprising:

a storage location to store an indicator to indicate whether the processor is configured to execute guest software in a mode that enables the guest software to operate at a privilege level intended by the guest software; and

logic to execute the guest software in said processor mode, to identify, within said processor mode, an attempt of the guest software to perform an operation restricted by said processor mode, to determine, within said processor mode, whether the attempt would fail if the guest software was running outside said processor mode, to allow the guest software to attempt the operation within said processor mode in response to determining that the attempt would fail if the guest software was running outside said processor mode, to transfer control over the operation to an operating system running within said processor mode in response to the attempt; and

to generate a virtualization trap in response to determining that the attempt would succeed if the guest software was running outside said processor mode.

5. The processor of claim 4 wherein the logic is to determine whether the attempt would fail by determining whether the guest software is running with sufficient privilege to perform the operation.

6. The processor of claim 4 wherein the logic is also to exit said processor mode to transfer control over the operation to a virtual machine monitor running outside said processor mode in response to determining that the attempt would succeed if the guest software was running outside said processor mode.

7. A system comprising:

a memory to store application software and an operating system; and

a processor to execute the application software in a processor mode that enables the application software to operate at a privilege level intended by the application software, to identify, within said processor mode, an attempt of the application software to perform an operation restricted by said processor mode, to determine, within said processor mode, whether the attempt would fail if the application software was running outside said processor mode, to allow the application software to attempt the operation within said processor mode in response to determining that the attempt would fall if the application software was running outside said processor mode, to transfer control over the operation to the operating system running within said processor mode in response to the attempt; and

to generate a virtualization trap in response to determining that the attempt would succeed if the application software was running outside said processor mode.

8. The system of claim 7 wherein the processor is to determine whether the attempt would fail by determining whether the application software is running with sufficient privilege to perform the operation.

9. The system of claim 7 wherein:

the memory is also to store a virtual machine monitor; and

the processor is also to exit said processor mode to transfer control over the operation to the virtual machine monitor running outside said processor mode in response to determining that the attempt would succeed.

10. A non-transitory computer readable storage medium that provides instructions, which when executed on a processor, cause the processor to:

present a virtual machine to guest software in a processor mode that enables the guest software to operate at a privilege level intended by the guest software;

handle a virtualization trap, where the virtualization trap is generated in response to an attempt of the guest software to perform an operation restricted by said processor mode and a determination, within said processor mode, that the attempt would succeed if the guest software was running outside the virtual machine; and

allow the guest software to attempt the operation within said processor mode in response to determining that the attempt would fall if the guest software was running outside said processor mode, and

transfer control over the operation to an operating system running within said processor mode in response to the attempt.

11. The non-transitory computer readable storage medium of claim 10 wherein the determination that the attempt would succeed includes determining whether the application software is running with sufficient privilege to perform the operation.