On Tue, May 03, 2022 at 12:49:34PM -0500, Seth Forshee wrote: > A task can be livepatched only when it is sleeping or it exits to > userspace. This may happen infrequently for a heavily loaded vCPU task, > leading to livepatch transition failures. > > Fake signals will be sent to tasks which fail patching via stack > checking. This will cause running vCPU tasks to exit guest mode, but > since no signal is pending they return to guest execution without > exiting to userspace. Fix this by treating a pending livepatch migration > like a pending signal, exiting to userspace with EINTR. This allows the > task to be patched, and userspace should re-excecute KVM_RUN to resume > guest execution. > > In my testing, systems where livepatching would timeout after 60 seconds > were able to load livepatches within a couple of seconds with this > change. > > Signed-off-by: Seth Forshee <sforshee@xxxxxxxxxxxxxxxx> > --- > Changes in v2: > - Added _TIF_SIGPENDING to XFER_TO_GUEST_MODE_WORK Clearly I meant _TIF_PATCH_PENDING here and not _TIF_SIGPENDING.
