On 04/06/2016 02:42, Yunhong Jiang wrote:
> +static int vmx_set_hv_timer(struct kvm_vcpu *vcpu, u64 guest_deadline_tsc)
> +{
> + u64 tscl = rdtsc(), delta_tsc;
> +
> + delta_tsc = guest_deadline_tsc - kvm_read_l1_tsc(vcpu, tscl);
> +
> + /* Convert to host delta tsc if tsc scaling is enabled */
> + if (vcpu->arch.tsc_scaling_ratio &&
> + u64_shl_div_u64(delta_tsc,
> + kvm_tsc_scaling_ratio_frac_bits,
> + vcpu->arch.tsc_scaling_ratio,
> + &delta_tsc))
> + return -1;
Please return -EOVERFLOW or -ERANGE. It's just aesthetic, but usually
in Linux functions do not return -1.
Thanks,
Paolo
> + /*
> + * If the delta tsc can't be fit in the 32 bit after the multi shift,
> + * we can't use the preemption timer.
> + * It's possible that it can be fit when vmentry happens late, but
> + * checking on every vmentry is costly, so fail earilier.
> + */
> + if (delta_tsc >> (cpu_preemption_timer_multi + 32))
> + return -1;
> +
> + vcpu->arch.hv_orig_tsc = tscl;
> + vcpu->arch.hv_deadline_tsc = tscl + delta_tsc;
> + vmcs_set_bits(PIN_BASED_VM_EXEC_CONTROL,
> + PIN_BASED_VMX_PREEMPTION_TIMER);
> + return 0;
> +}
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