# US 2020/0401439 A1 · System and method for trapping system calls for remote execution > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 2020/0401439 A1 - Document ID: US20200401439A1 - Status: Published application - Kind: A1 - Application number: 17/013,455 - Filed: 2020-09-04 - Published: 2020-12-24 - Earliest claimed: 2018-05-23 - Assignees: Parallels International GrnbH - Applicants: Parallels International GrnbH - Inventors: Andrey Naenko; Alexey Koryakin; Nikolay Dobrovolskiy; Serguei M. Beloussov - Web page: https://patentgrep.com/patent/US20200401439A1 ## CPC - G06F 9/45545: {Guest-host, i.e. hypervisor is an application program itself, e.g. VirtualBox} - G06F 9/45558: {Hypervisor-specific management and integration aspects} - G06F 9/4812: {by interrupt, e.g. masked} - G06F 9/547: {Remote procedure calls [RPC]; Web services} - G06F 2009/45583: {Memory management, e.g. access or allocation} - G06F 2009/45591: {Monitoring or debugging support} - G06F 2009/45595: {Network integration; Enabling network access in virtual machine instances} - G06F: ELECTRIC DIGITAL DATA PROCESSING (computer systems based on specific computational models G06N) ## Abstract Disclosed are systems and methods for executing system calls in a virtualized environment. A method includes executing, on a host, a host process corresponding to a guest process executing within a virtual machine and having an associated guest-process virtual address space, the host process having an associated host-process virtual address space. The method also includes mapping the host-process virtual address space and the guest-process virtual address space to a host physical memory, trapping a system call invoked by the guest process, and performing the trapped system call using the host process, wherein state changes in the host-process virtual address space caused by the trapped system call are reflected in the guest-process virtual address space. The method further includes causing execution of the guest process to be resumed after performing the trapped system call. ## Claims ### Claim 1 A method for executing system calls in a virtualized environment, wherein the method comprises: executing, on a host, a host process corresponding to a guest process executing within a virtual machine and having an associated guest-process virtual address space, the host process having an associated host-process virtual address space; mapping the host-process virtual address space and the guest-process virtual address space to a host physical memory; trapping a system call invoked by the guest process; performing the trapped system call using the host process, wherein state changes in the host-process virtual address space caused by the trapped system call are reflected in the guest-process virtual address space; and causing execution of the guest process to be resumed after performing the trapped system call. ### Claim 2 (depends on 1) The method of claim 1, wherein trapping the system call invoked by the guest process further comprises: protecting a model-specific register associated with a system-call target address from at least one of read access or write access; and catching a general protection exception caused by the guest process attempting to read the protected model-specific register associated with the system-call target address. ### Claim 3 (depends on 2) The method of claim 2, further comprising: responsive to determining the general protection exception is associated with an emulated system call, extracting a system call number and one or more system-call arguments associated with the trapped system call. ### Claim 4 (depends on 1) The method of claim 1, wherein mapping the host-process virtual address space and the guest-process virtual address space to the host physical memory further comprises: intercepting a memory-management system call to modify a memory mapping of the guest-process virtual address space; and performing the modification of the memory mapping on both the guest-process virtual address space and the host-process virtual address space. ### Claim 5 (depends on 1) The method of claim 1, wherein mapping the host-process virtual address space and the guest-process virtual address space to the host physical memory further comprises: invoking a memory mapping application programming interface (API) call to map at least a portion of a guest virtual address space range to a context of the host process. ### Claim 6 (depends on 1) The method of claim 1, wherein performing the trapped system call using the host process further comprises: modifying access protection of the host-process virtual address space to protect the host-process virtual address space from access; and in responsive to a protection fault caused by the system call attempting to access a portion of the host-process virtual address space, mapping a new guest page to the accessed portion and release protection of the accessed portion. ### Claim 7 (depends on 1) The method of claim 1, wherein performing the trapped system call using the host process further comprises: responsive to determining that the trapped system call includes a guest data pointer referencing a portion of the guest-process virtual address space, substituting the guest data pointer with a host data pointer referencing the same portion of the guest-process virtual address space. ### Claim 8 (depends on 1) The method of claim 1, further comprising: responsive to determining that the trapped system call is suitable for the guest process, forwarding the trapped system call through a virtualization stack of the virtual machine for handling. ### Claim 9 A system for executing system calls in a virtualized environment, wherein the system comprises: a physical memory device; and a processor configured to: execute a host process corresponding to a guest process executing within a virtual machine and having an associated guest-process virtual address space, the host process having an associated host-process virtual address space; map the host-process virtual address space and the guest-process virtual address space to a host physical memory; trap a system call invoked by the guest process; perform the trapped system call using the host process, wherein state changes in the host-process virtual address space caused by the trapped system call are reflected in the guest-process virtual address space; and cause execution of the guest process to be resumed after performing the trapped system call. ### Claim 10 (depends on 9) The system of claim 9, wherein to trap the system call invoked by the guest process is further, the processor is further configured to: protect a model-specific register associated with a system-call target address from at least one of read access and write access; and catch a general protection exception caused by the guest process attempting to read the protected model-specific register associated with the system-call target address. ### Claim 11 (depends on 10) The system of claim 10, wherein the processor is further configured to: responsive to determining the general protection exception is associated with an emulated system call, extract a system call number and one or more system-call arguments associated with the trapped system call. ### Claim 12 (depends on 9) The system of claim 9, wherein to map the host-process virtual address space and the guest-process virtual address space to the host physical memory, the processor is further configured to: intercept a memory-management system call to modify a memory mapping of the guest-process virtual address space; and perform the modification of the memory mapping on both the guest-process virtual address space and the host-process virtual address space. ### Claim 13 (depends on 9) The system of claim 9, wherein to map the host-process virtual address space and the guest-process virtual address space to the host physical memory, the processor is further configured to: invoke a memory mapping API call to map at least a portion of a guest virtual address space range to a context of the host process. ### Claim 14 (depends on 9) The system of claim 9, wherein to perform the trapped system call using the host process, the processor is further configured to: modify access protection of the host-process virtual address space to protect the host-process virtual address space from access; and in responsive to a protection fault caused by the system call attempting to access a portion of the host-process virtual address space, map a new guest page to the accessed portion and release protection of the accessed portion. ### Claim 15 (depends on 9) The system of claim 9, wherein to perform the trapped system call using the host process, the processor is further configured to: responsive to determining that the trapped system call includes a guest data pointer referencing a portion of the guest-process virtual address space, substitute the guest data pointer with a host data pointer referencing the same portion of the guest-process virtual address space. ### Claim 16 (depends on 9) The system of claim 9, wherein the processor is further configured to: responsive to determining that the trapped system call is suitable for the guest process, forward the trapped system call through a virtualization stack of the virtual machine for handling. ### Claim 17 A non-transitory computer readable medium comprising computer executable instructions, which when executed by a processor, cause the processor to perform operations to execute system calls in a virtualized environment, the operations comprising: executing, on a host, a host process corresponding to a guest process executing within a virtual machine and having an associated guest-process virtual address space, the host process having an associated host-process virtual address space; mapping the host-process virtual address space and the guest-process virtual address space to a host physical memory; trapping a system call invoked by the guest process; performing the trapped system call using the host process, wherein state changes in the host-process virtual address space caused by the trapped system call are reflected in the guest-process virtual address space; and causing execution of the guest process to be resumed after performing the trapped system call. ### Claim 18 (depends on 17) The non-transitory computer readable medium of claim 17, wherein trapping the system call invoked by the guest process further comprises: protecting a model-specific register associated with a system-call target address from at least one of read access and write access; catching a general protection exception caused by the guest process attempting to read the protected model-specific register associated with the system-call target address; and responsive to determining the general protection exception is associated with an emulated system call, extracting a system call number and one or more system-call arguments associated with the trapped system call. ### Claim 19 (depends on 17) The non-transitory computer readable medium of claim 17, wherein mapping the host-process virtual address space and the guest-process virtual address space to the host physical memory further comprises: intercepting a memory-management system call to modify a memory mapping of the guest-process virtual address space; and performing the modification of the memory mapping on both the guest-process virtual address space and the host-process virtual address space. ### Claim 20 (depends on 17) The non-transitory computer readable medium of claim 17, wherein performing the trapped system call using the host process further comprises: modifying access protection of the host-process virtual address space to protect the host-process virtual address space from access; and in responsive to a protection fault caused by the system call attempting to access a portion of the host-process virtual address space, mapping a new guest page to the accessed portion and release protection of the accessed portion.