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hpet: store full 64-bit target value of the counter

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Store the full 64-bit value at which the timer should fire.

This makes it possible to skip the imprecise hpet_calculate_diff()
step, and to remove the clamping of the period to 31 or 63 bits.

Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
This commit is contained in:
Paolo Bonzini 2024-07-16 12:26:36 +02:00
parent c236656737
commit 242d665396
1 changed files with 49 additions and 62 deletions
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111
hw/timer/hpet.c
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@ -54,6 +54,7 @@ typedef struct HPETTimer { /* timers */
uint64_t cmp; /* comparator */
uint64_t fsb; /* FSB route */
/* Hidden register state */
uint64_t cmp64; /* comparator (extended to counter width) */
uint64_t period; /* Last value written to comparator */
uint8_t wrap_flag; /* timer pop will indicate wrap for one-shot 32-bit
* mode. Next pop will be actual timer expiration.
@ -115,11 +116,6 @@ static uint32_t timer_enabled(HPETTimer *t)
}
static uint32_t hpet_time_after(uint64_t a, uint64_t b)
{
return ((int32_t)(b - a) < 0);
}
static uint32_t hpet_time_after64(uint64_t a, uint64_t b)
{
return ((int64_t)(b - a) < 0);
}
@ -156,29 +152,34 @@ static uint64_t hpet_get_ticks(HPETState *s)
return ns_to_ticks(qemu_clock_get_ns(QEMU_CLOCK_VIRTUAL) + s->hpet_offset);
}
/*
* calculate diff between comparator value and current ticks
*/
static inline uint64_t hpet_calculate_diff(HPETTimer *t, uint64_t current)
static uint64_t hpet_get_ns(HPETState *s, uint64_t tick)
{
return ticks_to_ns(tick) - s->hpet_offset;
}
/*
* calculate next value of the general counter that matches the
* target (either entirely, or the low 32-bit only depending on
* the timer mode).
*/
static uint64_t hpet_calculate_cmp64(HPETTimer *t, uint64_t cur_tick, uint64_t target)
{
if (t->config & HPET_TN_32BIT) {
uint32_t diff, cmp;
cmp = (uint32_t)t->cmp;
diff = cmp - (uint32_t)current;
diff = (int32_t)diff > 0 ? diff : (uint32_t)1;
return (uint64_t)diff;
uint64_t result = deposit64(cur_tick, 0, 32, target);
if (result < cur_tick) {
result += 0x100000000ULL;
}
return result;
} else {
uint64_t diff, cmp;
cmp = t->cmp;
diff = cmp - current;
diff = (int64_t)diff > 0 ? diff : (uint64_t)1;
return diff;
return target;
}
}
static uint64_t hpet_next_wrap(uint64_t cur_tick)
{
return (cur_tick | 0xffffffffU) + 1;
}
static void update_irq(struct HPETTimer *timer, int set)
{
uint64_t mask;
@ -260,7 +261,12 @@ static bool hpet_validate_num_timers(void *opaque, int version_id)
static int hpet_post_load(void *opaque, int version_id)
{
HPETState *s = opaque;
int i;
for (i = 0; i < s->num_timers; i++) {
HPETTimer *t = &s->timer[i];
t->cmp64 = hpet_calculate_cmp64(t, s->hpet_counter, t->cmp);
}
/* Recalculate the offset between the main counter and guest time */
if (!s->hpet_offset_saved) {
s->hpet_offset = ticks_to_ns(s->hpet_counter)
@ -356,14 +362,10 @@ static const VMStateDescription vmstate_hpet = {
}
};
static void hpet_arm(HPETTimer *t, uint64_t ticks)
static void hpet_arm(HPETTimer *t, uint64_t tick)
{
if (ticks < ns_to_ticks(INT64_MAX / 2)) {
timer_mod(t->qemu_timer,
qemu_clock_get_ns(QEMU_CLOCK_VIRTUAL) + ticks_to_ns(ticks));
} else {
timer_del(t->qemu_timer);
}
/* FIXME: Clamp period to reasonable min value? */
timer_mod(t->qemu_timer, hpet_get_ns(t->state, tick));
}
/*
@ -372,54 +374,44 @@ static void hpet_arm(HPETTimer *t, uint64_t ticks)
static void hpet_timer(void *opaque)
{
HPETTimer *t = opaque;
uint64_t diff;
uint64_t period = t->period;
uint64_t cur_tick = hpet_get_ticks(t->state);
if (timer_is_periodic(t) && period != 0) {
while (hpet_time_after(cur_tick, t->cmp64)) {
t->cmp64 += period;
}
if (t->config & HPET_TN_32BIT) {
while (hpet_time_after(cur_tick, t->cmp)) {
t->cmp = (uint32_t)(t->cmp + t->period);
}
t->cmp = (uint32_t)t->cmp64;
} else {
while (hpet_time_after64(cur_tick, t->cmp)) {
t->cmp += period;
}
}
diff = hpet_calculate_diff(t, cur_tick);
hpet_arm(t, diff);
} else if (t->config & HPET_TN_32BIT && !timer_is_periodic(t)) {
if (t->wrap_flag) {
diff = hpet_calculate_diff(t, cur_tick);
hpet_arm(t, diff);
t->wrap_flag = 0;
t->cmp = t->cmp64;
}
hpet_arm(t, t->cmp64);
} else if (t->wrap_flag) {
t->wrap_flag = 0;
hpet_arm(t, t->cmp64);
}
update_irq(t, 1);
}
static void hpet_set_timer(HPETTimer *t)
{
uint64_t diff;
uint32_t wrap_diff; /* how many ticks until we wrap? */
uint64_t cur_tick = hpet_get_ticks(t->state);
/* whenever new timer is being set up, make sure wrap_flag is 0 */
t->wrap_flag = 0;
diff = hpet_calculate_diff(t, cur_tick);
t->cmp64 = hpet_calculate_cmp64(t, cur_tick, t->cmp);
if (t->config & HPET_TN_32BIT) {
/* hpet spec says in one-shot 32-bit mode, generate an interrupt when
* counter wraps in addition to an interrupt with comparator match.
*/
if (t->config & HPET_TN_32BIT && !timer_is_periodic(t)) {
wrap_diff = 0xffffffff - (uint32_t)cur_tick;
if (wrap_diff < (uint32_t)diff) {
diff = wrap_diff;
/* hpet spec says in one-shot 32-bit mode, generate an interrupt when
* counter wraps in addition to an interrupt with comparator match.
*/
if (!timer_is_periodic(t) && t->cmp64 > hpet_next_wrap(cur_tick)) {
t->wrap_flag = 1;
hpet_arm(t, hpet_next_wrap(cur_tick));
return;
}
}
hpet_arm(t, diff);
hpet_arm(t, t->cmp64);
}
static void hpet_del_timer(HPETTimer *t)
@ -550,12 +542,7 @@ static void hpet_ram_write(void *opaque, hwaddr addr,
timer->cmp = deposit64(timer->cmp, shift, len, value);
}
if (timer_is_periodic(timer)) {
/*
* FIXME: Clamp period to reasonable min value?
* Clamp period to reasonable max value
*/
new_val = deposit64(timer->period, shift, len, value);
timer->period = MIN(new_val, (timer->config & HPET_TN_32BIT ? ~0u : ~0ull) >> 1);
timer->period = deposit64(timer->period, shift, len, value);
}
timer->config &= ~HPET_TN_SETVAL;
if (hpet_enabled(s)) {