On Fri, 7 Dec 2018 at 16:00, Peter Maydell <peter.mayd...@linaro.org> wrote: > > We use cpu_stop_current() to ensure the current CPU has stopped > from places like qemu_system_reset_request(). Unfortunately its > current implementation has a race. It calls qemu_cpu_stop(), > which sets cpu->stopped to true even though the CPU hasn't > actually stopped yet. The main thread will look at the flags > set by qemu_system_reset_request() and call pause_all_vcpus(). > pause_all_vcpus() waits for every cpu to have cpu->stopped true, > so it can continue (and we will start the system reset operation) > before the vcpu thread has got back to its top level loop. > > Instead, just set cpu->stop and call cpu_exit(). This will > cause the vcpu to exit back to the top level loop, and there > (as part of the wait_io_event code) it will call qemu_cpu_stop(). > > This fixes bugs where the reset request appeared to be ignored > or the CPU misbehaved because the reset operation started > to change vcpu state while the vcpu thread was still using it. > > Signed-off-by: Peter Maydell <peter.mayd...@linaro.org>
I'm going to put this in via target-arm.next, unless anybody would like to suggest another route. thanks -- PMM
