Input-output control system in a virtual machine system

Claim 2

An I/O control system in a virtual machine system having at least one virtual machine VM running under control of a virtual machine control program VMCP, having a direct I/O execution mode in which an I/O instruction from an operating system OS on the running VM for an I/O device (10-j) dedicated by the running VM and a related I/O interruption are directly executed without intervention of the V M CP and an indirect I/O execution mode in which the VMCP simulates the I/O instruction from the OS and the related I/O interruption, said I/O control system comprising: identification means for identifying the I/O device requesting switching to the direct I/O execution mode; judge means (Figs. la and lc) for judging a predetermined mode switching condition; and mode selection means (Figs. lb and ld) for selecting one of said two modes; wherein said identification means identifies the I/O device requesting the switching to the direct I/O execution mode and if the VM which contemplates the direct execution has not yet dedicated the I/O device requesting the mode switching when the identified I/O device meets the mode switching condition as judged by said judge means, the VM dedicates that I/O device, and if the VM has not yet dedicated an I/O interrupt subclass which controls the I/ O interruption of that I/O device, the VM dedicates that I/O interrupt subclass, and the VM switches the mode of said I/O device by said mode selection means from the indirect I/O execution mode to the direct I/O execution mode.

Claim 3

An I/O control system in a virtual machine system having at least one virtual machine VM running under control of a virtual machine control program VMCP, having a direct I/O execution mode in which an I/O instruction from an operating system OS on the running VM for an I/O device (10-j) dedicated by the running VM and a related I/O interruption are directly executed without intervention of the VMCP and an indirect I/O execution mode in which the VMCP simulates the I/O instruction from the OS and the related I/O interruption, said I/O control system comprising: identification means for identifying the I/O device requesting switching to the direct I/O execution mode; judge means for judging a predetermined mode switching condition; and examination means for examining a status of said I/O device; wherein when the I/O device in the direct I/O execution mode requests the switching to the indirect I/O execution mode, the VMCP examines the status of the I/O device which requests the switching to the indirect I/O execution mode by said examination means and then switches the mode of the I/O device by said mode selection means from the direct I/O execution mode to the indirect I/O execution mode.

Claim 4

An I/O control system in a virtual machine system having at least one virtual machine VM running under control of a virtual machine control program VMCP, having a direct I/O execution mode in which an I/O instruction from an operating system OS on the running VM for an I/O device (10-j) dedicated by the running VM and a related I/O interruption are directly executed without intervention of the VMCP and an indirect I/O execution mode in which the VMCP simulates the I/O instruction from the OS and the related I/O interruption, said I/O control system comprising: identification means for identifying the I/O device requesting switching to the direct I/O execution mode; judge means for judging a predetermined mode switching condition; and examination means for examining a status of said I/O device; wherein when the I/O device in the direct I/O execution mode requests the switching to the indirect I/O execution mode, the VMCP examines the status of the I/O device which requests the switching to the indirect I/O execution mode by said examination means and then switches the mode of the I/O device by said mode selection means from the direct I/O execution mode to the indirect I/O execution mode.

Claim 5

An I/O control system in a virtual machine system according to Claim 1, wherein the mode switching condition from the indirect I/O execution mode to the direct I/O execution mode is that the VM which contemplates the direct execution dedicates or can dedicate the I/O device requesting the direct execution, the VMCP has no I/O instruction execution request queue of the I/O device when the control has been shifted to the VM which contemplates the direct execution, the VMCP does not suspend the I/O interruption of the I/O device to be reflected to the VM, the I/O device is not executing the I/O instruction of other VM than the VM which contemplates the direct execution or the I/O instruction inherent to the VMCP or the related I/O interruption is not suspended, and the VM which contemplates the direct execution dedicates or can dedicate an I/O interrupt subclass which controls the I/O interruption relating to the I/O device.

Claim 6

An I/O control system in a virtual machine system having at least one virtual machine VM running under control of a virtual machine control program VMCP, having a direct I/O execution mode in which an I/O instruction from an operating system OS on the running VM for an I/O device (10-j) dedicated by the running VM and a related I/O interruption are directly executed without intervention of the VMCP and an indirect I/O execution mode in which the VMCP simulates the I/O instruction from the OS and the related I/O interruption, said I/O control system comprising: identification means for identifying the I/O device requesting switching to the direct I/O execution mode; judge means for judging a predetermined mode switching condition; mode selection means for selecting one of said two modes; and examination means for examining a status of said I/O device; wherein when the I/O device in the direct I/O execution mode requests the switching to the indirect I/O execution mode, the VMCP examines the status of the I/O device which requests the switching to the indirect I/O execution mode by said examination means and then switches the mode of the I/O device by said mode selection means from the direct I/O execution mode to the indirect I/O execution mode, and said switching is carried out by releasing the forcibe suspension by the VMCP of the I/O instruction execution request to the I/O device when the VMCP determines that the I/O device is not executing the I/O operation and the I/O interruption due to the I/O operation to the I/O device is not suspended, by said identification means for identifying the I/O device requesting the mode switching and said examination means for examining the status of the I/O device.

Claim 7

An I/O control system in a virtual machine system having at least one virtual machine VM running under control of a virtual machine control program VMCP, having a direct I/O execution mode in which an I/O instruction from an operating system OS on the running VM for an I/O device (10-j) dedicated by the running VM and a related I/O interruption are directly executed without intervention of the VMCP and an indirect I/O execution mode in which the VMCP simulates the I/O instruction from the OS and the related I/O interruption, said I/O control system comprising: identification means for identifying the I/O device requesting switching to the direct I/O execution mode; judge means for judging a predetermined mode switching condition; mode selection means for selecting one of said two modes; and examination means for examining a status of said I/O device; wherein when the I/O device in the direct I/O execution mode requests the switching to the indirect I/O execution mode, the VMCP examines the status of the I/O device which requests the switching to the indirect I/O execution mode by said examination means and then switches the mode of the I/O device by said mode selection means from the direct I/O execution mode to the indirect I/O execution mode, and said switching is carried out by releasing the forcibe suspension by the VMCP of the I/O instruction execution request to the I/O device when the VMCP determines that the I/O device is not executing the I/O operation and the I/O interruption due to the I/O operation to the I/O device is not suspended, by said identification means for identifying the I/O device requesting the mode switching and said examination means for examining the status of the I/O device.

Claim 8

An I/O control system in a virtual machine system having at least one virtual machine VM running under control of a virtual machine control program VMCP, having a direct I/O execution mode in which an I/O instruction from an operating system OS on the running VM for an I/O device dedicated by the running VM and a related I/O interruption are directly executed without intervention of the V M CP and an indirect I/O execution mode in which the VMCP simulates the I/O instruction from the OS and the related I/O interruption, said I/O control system comprising: identification means for identifying the I/O device requesting switching to the direct I/O execution mode; judge means for judging a predetermined mode switching condition; mode selection means for selecting one of said two modes; and examination means for examining a status of said I/O device; wherein when the I/O device in the direct I/O execution mode requests the switching to the indirect I/O execution mode, the VMCP examines the status of the I/O device which requests the switching to the indirect I/O execution mode by said examination means and then switches the mode of the I/O device by said mode selection means from the direct I/O execution mode to the indirect I/O execution mode, and said switching is carried out by examining the status of the I/O device by said identification means for identifying the I/O device requesting the mode switching and said examination means for examining the status of the I/O device a predetermined time after the mode switching request, and releasing the forcibe suspension by the VMCP of the I/O instruction execution request.

Claim 9

An I/O control system in a virtual machine system having at least one virtual machine VM running under control of a virtual machine control program VMCP, having a direct I/O execution mode in which an I/O instruction from an operating system OS on the running VM for an I/O device dedicated by the running VM and a related I/O interruption are directly executed without intervention of the V M CP and an indirect I/O execution mode in which the VMCP simulates the I/O instruction from the OS and the related I/O interruption, said I/O control system comprising: identification means for identifying the I/O device requesting switching to the direct I/O execution mode; judge means for judging a predetermined mode switching condition; mode selection means for selecting one of said two modes; and examination means for examining a status of said I/O device; wherein when the I/O device in the direct I/O execution mode requests the switching to the indirect I/O execution mode, the VMCP examines the status of the I/O device which requests the switching to the indirect I/O execution mode by said examination means and then switches the mode of the I/O device by said mode selection means from the direct I/O execution mode to the indirect I/O execution mode, and said switching is carried out by examining the status of the I/O device by said identification means for identifying the I/O device requesting the mode switching and said examination means for examining the status of the I/O device a predetermined time after the mode switching request, and releasing the forcibe suspension by the VMCP of the I/O instruction execution request.