KVM: VMX: Skip delta_tsc shift-and-divide if the dividend is zero

Ten percent of nothin' is... let me do the math here.  Nothin' into
nothin', carry the nothin'...

Cc: Wanpeng Li <wanpengli@tencent.com>
Reviewed-by: Liran Alon <liran.alon@oracle.com>
Signed-off-by: Sean Christopherson <sean.j.christopherson@intel.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

diff --git a/arch/x86/kvm/vmx/vmx.c b/arch/x86/kvm/vmx/vmx.c
index 60e2f0afa4d60b9ce898cdea885b69d245da311e..d8f101b58ab8fb84b2e78578b6a24b56d2711bab 100644 (file)
--- a/arch/x86/kvm/vmx/vmx.c
+++ b/arch/x86/kvm/vmx/vmx.c
@@ -7063,10 +7063,9 @@ static int vmx_set_hv_timer(struct kvm_vcpu *vcpu, u64 guest_deadline_tsc,
 
        /* Convert to host delta tsc if tsc scaling is enabled */
        if (vcpu->arch.tsc_scaling_ratio != kvm_default_tsc_scaling_ratio &&
-                       u64_shl_div_u64(delta_tsc,
+           delta_tsc && u64_shl_div_u64(delta_tsc,
                                kvm_tsc_scaling_ratio_frac_bits,
-                               vcpu->arch.tsc_scaling_ratio,
-                               &delta_tsc))
+                               vcpu->arch.tsc_scaling_ratio, &delta_tsc))
                return -ERANGE;
 
        /*