kvmppc_emulate_dec() uses dec_nsec of type unsigned long and does below calculation:
dec_nsec = vcpu->arch.dec;
dec_nsec *= 1000;
This will truncate if DEC value "vcpu->arch.dec" is greater than 0xffff_ffff/1000.
For example : For tb_ticks_per_usec = 4a, we can not set decrementer more than ~58ms.
Signed-off-by: Bharat Bhushan <bharat.bhushan@xxxxxxxxxxxxx>
---
arch/powerpc/kvm/emulate.c | 4 ++--
1 files changed, 2 insertions(+), 2 deletions(-)
diff --git a/arch/powerpc/kvm/emulate.c b/arch/powerpc/kvm/emulate.c
index 8af3bad..37f41f9 100644
--- a/arch/powerpc/kvm/emulate.c
+++ b/arch/powerpc/kvm/emulate.c
@@ -83,7 +83,7 @@ static bool kvmppc_dec_enabled(struct kvm_vcpu *vcpu)
void kvmppc_emulate_dec(struct kvm_vcpu *vcpu)
{
- unsigned long dec_nsec;
+ unsigned long long dec_nsec;
pr_debug("mtDEC: %x\n", vcpu->arch.dec);
#ifdef CONFIG_PPC_BOOK3S
@@ -105,7 +105,7 @@ void kvmppc_emulate_dec(struct kvm_vcpu *vcpu)
hrtimer_try_to_cancel(&vcpu->arch.dec_timer);
dec_nsec = vcpu->arch.dec;
dec_nsec *= 1000;
- dec_nsec /= tb_ticks_per_usec;
+ do_div(dec_nsec, tb_ticks_per_usec);
hrtimer_start(&vcpu->arch.dec_timer, ktime_set(0, dec_nsec),
HRTIMER_MODE_REL);
vcpu->arch.dec_jiffies = get_tb();
--
1.7.0.4
--
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