Abstract: An example method of virtualizing a host virtual counter and timer in a central processing unit (CPU) of a virtualized host computer includes: creating, by a hypervisor of the host computer in response to power on of a virtual machine (VM), a guest virtual counter, the guest virtual counter comprising a data structure including scaling factors; mapping a shared memory page having the data structure into an address space of memory allocated to the VM; and notifying a guest operating system (OS) of the VM of a location in the address space for the shared memory page having the data structure, the guest OS being paravirtualized to scale the host virtual counter and timer based on the scaling factors of the guest virtual counter.

Abstract: An example method of managing guest time for a virtual machine (VM) supported by a hypervisor of a virtualized host computer includes: configuring, by the hypervisor, a central processing unit (CPU) of the host computer to trap, to the hypervisor, access by guest code in the VM to a physical counter and timer of the CPU; configuring, by the hypervisor, the guest code in the VM to use the physical counter and timer of the CPU rather than a virtual counter and timer of the CPU; trapping, at the hypervisor, an access to the physical counter and timer by the guest code; and executing, by the hypervisor, the access to the physical counter and timer on behalf of the guest code while compensating for an adjustment of a system count of the physical counter and timer to maintain the guest time as scaled with respect to frequency of the physical counter and timer.

Abstract: System and method for analyzing operating systems uses information regarding access bits set in page table entries to identify code segments of an operating system that were not executed. These code segments are identified by first identifying untouched memory pages using the information regarding the access bits in the page table entries, and then identifying functions of the operating system using physical memory addresses for the untouched memory pages. The identified functions represent the code segments of the operating system that were not executed.

Abstract: System and computer-implemented method allocates log buffers at a host server, receives log data from a data processing unit (DPU) that is connected to the host server and stores the log data in the log buffers at the host server, and transmits the log data stored in the log buffers back to the DPU to be stored in storage of the DPU such that the host server is used to temporarily store the log data.

Abstract: System and computer-implemented method enables a hardware watchdog timer in a data processing unit (DPU) and detects that a host server that is connected to the DPU is unresponsive when the hardware watchdog timer expires without receiving a timer reset request from a host watchdog service timer thread running in the host server.

Abstract: An example method of exception handling in a computer system is described. The computer system includes a physical central processing unit (PCPU) and a system memory, the system memory storing a first stack, a second stack, and a double fault stack associated with the PCPU. The method includes: storing, by an exception handler executing in the computer system, an exception frame on the double fault stack in response to a stack overflow condition of the first stack; switching, by the exception handler, a first stack pointer of the PCPU from pointing to the first stack to pointing to the double fault stack; setting a current stack pointer of the PCPU to the first stack pointer; and executing software on the PCPU with the current stack pointer pointing to the double fault stack.

Abstract: An example method of exception handling in a computer system is described. The computer system includes a physical central processing unit (PCPU) and a system memory, the system memory storing a first stack, a second stack, and a double fault stack associated with the PCPU. The method includes: storing, by an exception handler executing in the computer system, an exception frame on the double fault stack in response to a stack overflow condition of the first stack; switching, by the exception handler, a first stack pointer of the PCPU from pointing to the first stack to pointing to the double fault stack; setting a current stack pointer of the PCPU to the first stack pointer; and executing software on the PCPU with the current stack pointer pointing to the double fault stack.

Abstract: An example method of managing guest time for a virtual machine (VM) supported by a hypervisor of a virtualized host computer includes: configuring, by the hypervisor, a central processing unit (CPU) of the host computer to trap, to the hypervisor, access by guest code in the VM to a physical counter and timer of the CPU; configuring, by the hypervisor, the guest code in the VM to use the physical counter and timer of the CPU rather than a virtual counter and timer of the CPU; trapping, at the hypervisor, an access to the physical counter and timer by the guest code; and executing, by the hypervisor, the access to the physical counter and timer on behalf of the guest code while compensating for an adjustment of a system count of the physical counter and timer to maintain the guest time as scaled with respect to frequency of the physical counter and timer.

Abstract: An example method of virtualizing a host virtual counter and timer in a central processing unit (CPU) of a virtualized host computer includes: creating, by a hypervisor of the host computer in response to power on of a virtual machine (VM), a guest virtual counter, the guest virtual counter comprising a data structure including scaling factors; mapping a shared memory page having the data structure into an address space of memory allocated to the VM; and notifying a guest operating system (OS) of the VM of a location in the address space for the shared memory page having the data structure, the guest OS being paravirtualized to scale the host virtual counter and timer based on the scaling factors of the guest virtual counter.

Abstract: A method for booting a computer system includes: loading a first stage bootloader of a plurality of first stage bootloaders from a boot image based on a known configuration of the computer system; executing the first stage bootloader to identify a selected bootbank of a plurality of bootbanks in the boot image based on the known configuration of the computer system; executing, by the first stage bootloader, a second stage bootloader from the boot image with an instruction to boot from the selected bootbank; and executing, by the second stage bootloader, a binary file in the selected bootbank.