Re: [PATCH] KVM: x86: Use do_div for tsc deadline calculation

From: Randy Dunlap
Date: Fri Sep 30 2011 - 13:35:58 EST


On 09/30/11 04:50, Jan Kiszka wrote:
> Required on i386 hosts.
>
> Signed-off-by: Jan Kiszka <jan.kiszka@xxxxxxxxxxx>

Reported-by: Randy Dunlap <rdunlap@xxxxxxxxxxxx>
Acked-by: Randy Dunlap <rdunlap@xxxxxxxxxxxx>

Thanks.

> ---
> arch/x86/kvm/lapic.c | 7 ++++---
> 1 files changed, 4 insertions(+), 3 deletions(-)
>
> diff --git a/arch/x86/kvm/lapic.c b/arch/x86/kvm/lapic.c
> index f9385ec..92390dc 100644
> --- a/arch/x86/kvm/lapic.c
> +++ b/arch/x86/kvm/lapic.c
> @@ -740,9 +740,10 @@ static void start_apic_timer(struct kvm_lapic *apic)
>
> now = apic->lapic_timer.timer.base->get_time();
> guest_tsc = kvm_x86_ops->read_l1_tsc(vcpu);
> - if (likely(tscdeadline > guest_tsc))
> - ns = (tscdeadline - guest_tsc)
> - * 1000000L / this_tsc_khz;
> + if (likely(tscdeadline > guest_tsc)) {
> + ns = (tscdeadline - guest_tsc) * 1000000ULL;
> + do_div(ns, this_tsc_khz);
> + }
> hrtimer_start(&apic->lapic_timer.timer,
> ktime_add_ns(now, ns), HRTIMER_MODE_ABS);
>


--
~Randy
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