• Thomas Gleixner's avatar
    entry: Provide infrastructure for work before transitioning to guest mode · 935ace2f
    Thomas Gleixner authored
    Entering a guest is similar to exiting to user space. Pending work like
    handling signals, rescheduling, task work etc. needs to be handled before
    that.
    
    Provide generic infrastructure to avoid duplication of the same handling
    code all over the place.
    
    The transfer to guest mode handling is different from the exit to usermode
    handling, e.g. vs. rseq and live patching, so a separate function is used.
    
    The initial list of work items handled is:
    
        TIF_SIGPENDING, TIF_NEED_RESCHED, TIF_NOTIFY_RESUME
    
    Architecture specific TIF flags can be added via defines in the
    architecture specific include files.
    
    The calling convention is also different from the syscall/interrupt entry
    functions as KVM invokes this from the outer vcpu_run() loop with
    interrupts and preemption enabled. To prevent missing a pending work item
    it invokes a check for pending TIF work from interrupt disabled code right
    before transitioning to guest mode. The lockdep, RCU and tracing state
    handling is also done directly around the switch to and from guest mode.
    Signed-off-by: default avatarThomas Gleixner <tglx@linutronix.de>
    Link: https://lkml.kernel.org/r/20200722220519.833296398@linutronix.de
    935ace2f
kvm.c 1.21 KB