From: Christian Svensson <blue...@google.com> If the host decrements the counter register that results in a negative delta. This is then passed to muldiv64 which only handles unsigned numbers resulting in bogus results.
This fix ensures the delta being operated on is positive. Test case: kexec a kernel using aspeed_timer and it will freeze on the second bootup when the kernel initializes the timer. With this patch that no longer happens and the timer appears to run OK. Signed-off-by: Christian Svensson <blue...@google.com> Signed-off-by: Cédric Le Goater <c...@kaod.org> --- hw/timer/aspeed_timer.c | 6 +++++- 1 file changed, 5 insertions(+), 1 deletion(-) diff --git a/hw/timer/aspeed_timer.c b/hw/timer/aspeed_timer.c index 9988b8fbbf17..53b70f859c86 100644 --- a/hw/timer/aspeed_timer.c +++ b/hw/timer/aspeed_timer.c @@ -275,7 +275,11 @@ static void aspeed_timer_set_value(AspeedTimerCtrlState *s, int timer, int reg, int64_t delta = (int64_t) value - (int64_t) calculate_ticks(t, now); uint32_t rate = calculate_rate(t); - t->start += muldiv64(delta, NANOSECONDS_PER_SECOND, rate); + if (delta >= 0) { + t->start += muldiv64(delta, NANOSECONDS_PER_SECOND, rate); + } else { + t->start -= muldiv64(-delta, NANOSECONDS_PER_SECOND, rate); + } aspeed_timer_mod(t); } break; -- 2.20.1