diff options
| author | Paolo Bonzini <pbonzini@redhat.com> | 2024-07-16 12:35:39 +0200 |
|---|---|---|
| committer | Paolo Bonzini <pbonzini@redhat.com> | 2024-07-22 19:19:44 +0200 |
| commit | 7c912ffb59e8137091894d767433e65c3df8b0bf (patch) | |
| tree | 6d6fb82a6240bed06728ba31e96cd5fb535f9fe7 | |
| parent | 242d665396407f83a6acbffc804882eeb21cfdad (diff) | |
hpet: avoid timer storms on periodic timers
If the period is set to a value that is too low, there could be no
time left to run the rest of QEMU. Do not trigger interrupts faster
than 1 MHz.
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
| -rw-r--r-- | hw/timer/hpet.c | 13 |
1 files changed, 11 insertions, 2 deletions
diff --git a/hw/timer/hpet.c b/hw/timer/hpet.c index 1654b7cb8b..471950adef 100644 --- a/hw/timer/hpet.c +++ b/hw/timer/hpet.c @@ -59,6 +59,7 @@ typedef struct HPETTimer { /* timers */ uint8_t wrap_flag; /* timer pop will indicate wrap for one-shot 32-bit * mode. Next pop will be actual timer expiration. */ + uint64_t last; /* last value armed, to avoid timer storms */ } HPETTimer; struct HPETState { @@ -266,6 +267,7 @@ static int hpet_post_load(void *opaque, int version_id) for (i = 0; i < s->num_timers; i++) { HPETTimer *t = &s->timer[i]; t->cmp64 = hpet_calculate_cmp64(t, s->hpet_counter, t->cmp); + t->last = qemu_clock_get_ns(QEMU_CLOCK_VIRTUAL) - NANOSECONDS_PER_SECOND; } /* Recalculate the offset between the main counter and guest time */ if (!s->hpet_offset_saved) { @@ -364,8 +366,15 @@ static const VMStateDescription vmstate_hpet = { static void hpet_arm(HPETTimer *t, uint64_t tick) { - /* FIXME: Clamp period to reasonable min value? */ - timer_mod(t->qemu_timer, hpet_get_ns(t->state, tick)); + uint64_t ns = hpet_get_ns(t->state, tick); + + /* Clamp period to reasonable min value (1 us) */ + if (timer_is_periodic(t) && ns - t->last < 1000) { + ns = t->last + 1000; + } + + t->last = ns; + timer_mod(t->qemu_timer, ns); } /* |