From: ysay ysaydong@gmail.com

When guest_halt_poll_allow_shrink=N,setting guest_halt_poll_ns from a large value to 0 does not reset the CPU polling time, despite guest_halt_poll_ns being intended as a mandatory maximum time limit.

The problem was situated in the adjust_poll_limit() within drivers/cpuidle/governors/haltpoll.c:79.

Specifically, when guest_halt_poll_allow_shrink was set to N, resetting guest_halt_poll_ns to zero did not lead to executing any section of code that adjusts dev->poll_limit_ns.

The issue has been resolved by relocating the check and assignment for dev->poll_limit_ns outside of the conditional block. This ensures that every modification to guest_halt_poll_ns properly influences the CPU polling time.

Signed-off-by: ysay ysaydong@gmail.com Fixes: 2cffe9f6b96f ("cpuidle: add haltpoll governor") --- drivers/cpuidle/governors/haltpoll.c | 14 +++++++------- 1 file changed, 7 insertions(+), 7 deletions(-)

diff --git a/drivers/cpuidle/governors/haltpoll.c b/drivers/cpuidle/governors/haltpoll.c index 663b7f164..99c6260d7 100644 --- a/drivers/cpuidle/governors/haltpoll.c +++ b/drivers/cpuidle/governors/haltpoll.c @@ -78,26 +78,22 @@ static int haltpoll_select(struct cpuidle_driver *drv,

static void adjust_poll_limit(struct cpuidle_device *dev, u64 block_ns) { - unsigned int val; + unsigned int val = dev->poll_limit_ns;

/* Grow cpu_halt_poll_us if * cpu_halt_poll_us < block_ns < guest_halt_poll_us */ if (block_ns > dev->poll_limit_ns && block_ns <= guest_halt_poll_ns) { - val = dev->poll_limit_ns * guest_halt_poll_grow; + val *= guest_halt_poll_grow;

if (val < guest_halt_poll_grow_start) val = guest_halt_poll_grow_start; - if (val > guest_halt_poll_ns) - val = guest_halt_poll_ns;

trace_guest_halt_poll_ns_grow(val, dev->poll_limit_ns); - dev->poll_limit_ns = val; } else if (block_ns > guest_halt_poll_ns && guest_halt_poll_allow_shrink) { unsigned int shrink = guest_halt_poll_shrink;

- val = dev->poll_limit_ns; if (shrink == 0) { val = 0; } else { @@ -108,8 +104,12 @@ static void adjust_poll_limit(struct cpuidle_device *dev, u64 block_ns) }

trace_guest_halt_poll_ns_shrink(val, dev->poll_limit_ns); - dev->poll_limit_ns = val; } + + if (val > guest_halt_poll_ns) + val = guest_halt_poll_ns; + + dev->poll_limit_ns = val; }

/**