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KVM: PPC: Fix DEC truncation for greater than 0xffff_ffff/1000

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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@freescale.com>
Acked-by: Liu Yu <yu.liu@freescale.com>
Signed-off-by: Alexander Graf <agraf@suse.de>
Signed-off-by: Avi Kivity <avi@redhat.com>
This commit is contained in:
Bharat Bhushan 2011-10-19 09:46:06 +05:30 committed by Avi Kivity
parent f9208427f7
commit dc2babfea5
1 changed files with 7 additions and 5 deletions
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12
arch/powerpc/kvm/emulate.c
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@ -84,6 +84,7 @@ static int kvmppc_dec_enabled(struct kvm_vcpu *vcpu)
void kvmppc_emulate_dec(struct kvm_vcpu *vcpu)
{
unsigned long dec_nsec;
unsigned long long dec_time;
pr_debug("mtDEC: %x\n", vcpu->arch.dec);
#ifdef CONFIG_PPC_BOOK3S
@ -103,11 +104,12 @@ void kvmppc_emulate_dec(struct kvm_vcpu *vcpu)
* host ticks. */
hrtimer_try_to_cancel(&vcpu->arch.dec_timer);
dec_nsec = vcpu->arch.dec;
dec_nsec *= 1000;
dec_nsec /= tb_ticks_per_usec;
hrtimer_start(&vcpu->arch.dec_timer, ktime_set(0, dec_nsec),
HRTIMER_MODE_REL);
dec_time = vcpu->arch.dec;
dec_time *= 1000;
do_div(dec_time, tb_ticks_per_usec);
dec_nsec = do_div(dec_time, NSEC_PER_SEC);
hrtimer_start(&vcpu->arch.dec_timer,
ktime_set(dec_time, dec_nsec), HRTIMER_MODE_REL);
vcpu->arch.dec_jiffies = get_tb();
} else {
hrtimer_try_to_cancel(&vcpu->arch.dec_timer);