From patchwork Wed Jan 4 01:10:09 2012 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit Subject: [11/50] Fix DEC truncation for greater than 0xffff_ffff/1000 Date: Tue, 03 Jan 2012 15:10:09 -0000 From: Alexander Graf X-Patchwork-Id: 134169 Message-Id: <1325639448-9494-12-git-send-email-agraf@suse.de> To: kvm-ppc@vger.kernel.org Cc: kvm list , Avi Kivity , Marcelo Tosatti , Bharat Bhushan , Bharat Bhushan From: Bharat Bhushan 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 Acked-by: Liu Yu Signed-off-by: Alexander Graf --- arch/powerpc/kvm/emulate.c | 12 +++++++----- 1 files changed, 7 insertions(+), 5 deletions(-) diff --git a/arch/powerpc/kvm/emulate.c b/arch/powerpc/kvm/emulate.c index 141dce3..4337f99 100644 --- a/arch/powerpc/kvm/emulate.c +++ b/arch/powerpc/kvm/emulate.c @@ -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);