[patch 18/26] KVM: fix LAPIC timer period overflow

Greg KH
2009-10-09T23:17:43Z

[-- Attachment #1: kvm-fix-lapic-timer-period-overflow.patch --]
[-- Type: text/plain, Size: 953 bytes --]

2.6.31-stable review patch. If anyone has any objections, please let us know.

------------------
From: Aurelien Jarno <aurelien@aurel32.net>

commit b2d83cfa3fdefe5c6573d443d099a18dc3a93c5f upstream.

Don't overflow when computing the 64-bit period from 32-bit registers.

Fixes sourceforge bug #2826486.

Signed-off-by: Aurelien Jarno <aurelien@aurel32.net>
Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

---
arch/x86/kvm/lapic.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)

--- a/arch/x86/kvm/lapic.c
+++ b/arch/x86/kvm/lapic.c
@@ -567,7 +567,7 @@ static void start_apic_timer(struct kvm_
{
ktime_t now = apic->lapic_timer.timer.base->get_time();

- apic->lapic_timer.period = apic_get_reg(apic, APIC_TMICT) *
+ apic->lapic_timer.period = (u64)apic_get_reg(apic, APIC_TMICT) *
APIC_BUS_CYCLE_NS * apic->divide_count;
atomic_set(&apic->lapic_timer.pending, 0);