| Message ID | 1320801489-18193-1-git-send-email-jcmvbkbc@gmail.com |
|---|---|
| State | New |
| Headers | show |
On 11/08/2011 07:18 PM, Max Filippov wrote: > hpet_timer timer callback rearms itself based on difference between > current HPET tick counter and comparator value. Difference calculated by > the hpet_calculate_diff function is limited to non-negative values. > > cur_tick is calculated via hpet_get_ticks that uses qemu_get_clock_ns(vm_clock). > > With -icount enabled vm_clock doesn't advance during qemu_run_timers > loop thus once difference is zero, qemu_run_timers loops forever > handling hpet_timer. > > Limit hpet_calculate_diff results to positive only values to avoid that > infinite loop. > > This fixes the following qemu-system-x86_64 hang when it reaches > timer_irq_works() in the linux bootup: > > [ 0.000000] Fast TSC calibration using PIT > [ 0.000000] Detected 1000.054 MHz processor. > [ 0.000031] Calibrating delay loop (skipped), value calculated using timer frequency.. 2000.10 BogoMIPS (lpj=10000540) > [ 0.000404] pid_max: default: 32768 minimum: 301 > [ 0.001138] Mount-cache hash table entries: 256 > [ 0.003883] Initializing cgroup subsys ns > [ 0.004035] Initializing cgroup subsys cpuacct > [ 0.004280] Initializing cgroup subsys freezer > [ 0.004790] Performance Events: AMD PMU driver. > [ 0.004985] ... version: 0 > [ 0.005134] ... bit width: 48 > [ 0.005285] ... generic registers: 4 > [ 0.005437] ... value mask: 0000ffffffffffff > [ 0.005625] ... max period: 00007fffffffffff > [ 0.005807] ... fixed-purpose events: 0 > [ 0.005957] ... event mask: 000000000000000f > [ 0.006275] SMP alternatives: switching to UP code > > Signed-off-by: Max Filippov<jcmvbkbc@gmail.com> Applied. Thanks. Regards, Anthony Liguori > --- > hw/hpet.c | 4 ++-- > 1 files changed, 2 insertions(+), 2 deletions(-) > > diff --git a/hw/hpet.c b/hw/hpet.c > index 12bd64d..6e6ea52 100644 > --- a/hw/hpet.c > +++ b/hw/hpet.c > @@ -157,14 +157,14 @@ static inline uint64_t hpet_calculate_diff(HPETTimer *t, uint64_t current) > > cmp = (uint32_t)t->cmp; > diff = cmp - (uint32_t)current; > - diff = (int32_t)diff> 0 ? diff : (uint32_t)0; > + diff = (int32_t)diff> 0 ? diff : (uint32_t)1; > return (uint64_t)diff; > } else { > uint64_t diff, cmp; > > cmp = t->cmp; > diff = cmp - current; > - diff = (int64_t)diff> 0 ? diff : (uint64_t)0; > + diff = (int64_t)diff> 0 ? diff : (uint64_t)1; > return diff; > } > }
diff --git a/hw/hpet.c b/hw/hpet.c index 12bd64d..6e6ea52 100644 --- a/hw/hpet.c +++ b/hw/hpet.c @@ -157,14 +157,14 @@ static inline uint64_t hpet_calculate_diff(HPETTimer *t, uint64_t current) cmp = (uint32_t)t->cmp; diff = cmp - (uint32_t)current; - diff = (int32_t)diff > 0 ? diff : (uint32_t)0; + diff = (int32_t)diff > 0 ? diff : (uint32_t)1; return (uint64_t)diff; } else { uint64_t diff, cmp; cmp = t->cmp; diff = cmp - current; - diff = (int64_t)diff > 0 ? diff : (uint64_t)0; + diff = (int64_t)diff > 0 ? diff : (uint64_t)1; return diff; } }
hpet_timer timer callback rearms itself based on difference between current HPET tick counter and comparator value. Difference calculated by the hpet_calculate_diff function is limited to non-negative values. cur_tick is calculated via hpet_get_ticks that uses qemu_get_clock_ns(vm_clock). With -icount enabled vm_clock doesn't advance during qemu_run_timers loop thus once difference is zero, qemu_run_timers loops forever handling hpet_timer. Limit hpet_calculate_diff results to positive only values to avoid that infinite loop. This fixes the following qemu-system-x86_64 hang when it reaches timer_irq_works() in the linux bootup: [ 0.000000] Fast TSC calibration using PIT [ 0.000000] Detected 1000.054 MHz processor. [ 0.000031] Calibrating delay loop (skipped), value calculated using timer frequency.. 2000.10 BogoMIPS (lpj=10000540) [ 0.000404] pid_max: default: 32768 minimum: 301 [ 0.001138] Mount-cache hash table entries: 256 [ 0.003883] Initializing cgroup subsys ns [ 0.004035] Initializing cgroup subsys cpuacct [ 0.004280] Initializing cgroup subsys freezer [ 0.004790] Performance Events: AMD PMU driver. [ 0.004985] ... version: 0 [ 0.005134] ... bit width: 48 [ 0.005285] ... generic registers: 4 [ 0.005437] ... value mask: 0000ffffffffffff [ 0.005625] ... max period: 00007fffffffffff [ 0.005807] ... fixed-purpose events: 0 [ 0.005957] ... event mask: 000000000000000f [ 0.006275] SMP alternatives: switching to UP code Signed-off-by: Max Filippov <jcmvbkbc@gmail.com> --- hw/hpet.c | 4 ++-- 1 files changed, 2 insertions(+), 2 deletions(-)