[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] [Xen-changelog] [xen-unstable] hvm: hpet: Clamp period to sane values to prevent excessive looping in
# HG changeset patch # User Keir Fraser <keir.fraser@xxxxxxxxxx> # Date 1199874733 0 # Node ID 1b2be7cf0b7b4b639b7d6f027545930021ebe1e0 # Parent b5b3e27f1af3f709a7795d407b567a7b4db533f0 hvm: hpet: Clamp period to sane values to prevent excessive looping in hpet_timer_fn(), or excessive numbers of set_timer() callbacks. Signed-off-by: Keir Fraser <keir.fraser@xxxxxxxxxx> --- xen/arch/x86/hvm/hpet.c | 26 +++++++++++++++++++------- 1 files changed, 19 insertions(+), 7 deletions(-) diff -r b5b3e27f1af3 -r 1b2be7cf0b7b xen/arch/x86/hvm/hpet.c --- a/xen/arch/x86/hvm/hpet.c Wed Jan 09 10:11:31 2008 +0000 +++ b/xen/arch/x86/hvm/hpet.c Wed Jan 09 10:32:13 2008 +0000 @@ -303,7 +303,10 @@ static void hpet_write( } if ( new_val & HPET_TN_32BIT ) + { h->hpet.timers[tn].cmp = (uint32_t)h->hpet.timers[tn].cmp; + h->hpet.period[tn] = (uint32_t)h->hpet.period[tn]; + } break; @@ -317,7 +320,17 @@ static void hpet_write( (h->hpet.timers[tn].config & HPET_TN_SETVAL) ) h->hpet.timers[tn].cmp = new_val; else + { + /* + * Clamp period to reasonable min/max values: + * - minimum is 900us, same as timers controlled by vpt.c + * - maximum is to prevent overflow in time_after() calculations + */ + if ( hpet_tick_to_ns(h, new_val) < MICROSECS(900) ) + new_val = (MICROSECS(900) << 10) / h->hpet_to_ns_scale; + new_val &= (timer_is_32bit(h, tn) ? ~0u : ~0ull) >> 1; h->hpet.period[tn] = new_val; + } h->hpet.timers[tn].config &= ~HPET_TN_SETVAL; if ( hpet_enabled(h) ) hpet_set_timer(h, tn); @@ -376,7 +389,7 @@ static void hpet_route_interrupt(HPETSta return; } - /* We only support edge-triggered interrupt now */ + /* We support only edge-triggered interrupt. */ spin_lock(&d->arch.hvm_domain.irq_lock); vioapic_irq_positive_edge(d, tn_int_route); spin_unlock(&d->arch.hvm_domain.irq_lock); @@ -401,20 +414,19 @@ static void hpet_timer_fn(void *opaque) if ( timer_is_periodic(h, tn) && (h->hpet.period[tn] != 0) ) { - uint64_t mc = hpet_read_maincounter(h); + uint64_t mc = hpet_read_maincounter(h), period = h->hpet.period[tn]; if ( timer_is_32bit(h, tn) ) { while ( hpet_time_after(mc, h->hpet.timers[tn].cmp) ) h->hpet.timers[tn].cmp = (uint32_t)( - h->hpet.timers[tn].cmp + h->hpet.period[tn]); + h->hpet.timers[tn].cmp + period); } else { while ( hpet_time_after64(mc, h->hpet.timers[tn].cmp) ) - h->hpet.timers[tn].cmp += h->hpet.period[tn]; - } - set_timer(&h->timers[tn], - NOW() + hpet_tick_to_ns(h, h->hpet.period[tn])); + h->hpet.timers[tn].cmp += period; + } + set_timer(&h->timers[tn], NOW() + hpet_tick_to_ns(h, period)); } spin_unlock(&h->lock); _______________________________________________ Xen-changelog mailing list Xen-changelog@xxxxxxxxxxxxxxxxxxx http://lists.xensource.com/xen-changelog
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