From dd8e0a08e0823f193744290ebe1c16fe19642c91 Mon Sep 17 00:00:00 2001 From: Keir Fraser Date: Fri, 15 Jun 2007 09:42:39 +0100 Subject: [PATCH] hvm: Fix multiplication overflow in hvm/pmtimer.c Too many ACPI events (SCI) are raised on hvm because of multiplication overflow. FREQUENCE_PMTIMER=3579545 (1000000000ULL << 32) / FREQUENCE_PMTIMER = 0xae9a7b1663a pmt_cycles_until_flip =~ 0x80000000 0xae9a7b1663a*0x80000000 = overflow!!! Signed-off-by: Kouya Shimura --- xen/arch/x86/hvm/pmtimer.c | 15 +++++++-------- 1 file changed, 7 insertions(+), 8 deletions(-) diff --git a/xen/arch/x86/hvm/pmtimer.c b/xen/arch/x86/hvm/pmtimer.c index e0c803910f..7d848b4245 100644 --- a/xen/arch/x86/hvm/pmtimer.c +++ b/xen/arch/x86/hvm/pmtimer.c @@ -50,7 +50,6 @@ #define TMR_VAL_MASK (0xffffffff) #define TMR_VAL_MSB (0x80000000) - /* Dispatch SCIs based on the PM1a_STS and PM1a_EN registers */ static void pmt_update_sci(PMTState *s) { @@ -89,19 +88,19 @@ static void pmt_timer_callback(void *opaque) PMTState *s = opaque; uint32_t pmt_cycles_until_flip; uint64_t time_until_flip; - + /* Recalculate the timer and make sure we get an SCI if we need one */ pmt_update_time(s); - + /* How close are we to the next MSB flip? */ pmt_cycles_until_flip = TMR_VAL_MSB - (s->pm.tmr_val & (TMR_VAL_MSB - 1)); - + /* Overall time between MSB flips */ - time_until_flip = (1000000000ULL << 31) / FREQUENCE_PMTIMER; - + time_until_flip = (1000000000ULL << 23) / FREQUENCE_PMTIMER; + /* Reduced appropriately */ - time_until_flip = (time_until_flip * pmt_cycles_until_flip) / (1ULL<<31); - + time_until_flip = (time_until_flip * pmt_cycles_until_flip) >> 23; + /* Wake up again near the next bit-flip */ set_timer(&s->timer, NOW() + time_until_flip + MILLISECS(1)); } -- 2.30.2