[PATCH 7/7] KVM: VMX: Skip delta_tsc shift-and-divide if the dividend is zero

From: Sean Christopherson <sean.j.christopherson@intel.com>
To: "Paolo Bonzini" <pbonzini@redhat.com>,
	"Radim Krčmář" <rkrcmar@redhat.com>
Cc: kvm@vger.kernel.org,
	Sean Christopherson <sean.j.christopherson@intel.com>,
	Liran Alon <liran.alon@oracle.com>,
	Wanpeng Li <wanpengli@tencent.com>
Subject: [PATCH 7/7] KVM: VMX: Skip delta_tsc shift-and-divide if the dividend is zero
Date: Fri, 12 Apr 2019 13:18:34 -0700	[thread overview]
Message-ID: <20190412201834.10831-8-sean.j.christopherson@intel.com> (raw)
In-Reply-To: <20190412201834.10831-1-sean.j.christopherson@intel.com>

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

Cc: Wanpeng Li <wanpengli@tencent.com>
Signed-off-by: Sean Christopherson <sean.j.christopherson@intel.com>
---
 arch/x86/kvm/vmx/vmx.c | 5 ++---
 1 file changed, 2 insertions(+), 3 deletions(-)

diff --git a/arch/x86/kvm/vmx/vmx.c b/arch/x86/kvm/vmx/vmx.c
index a3211e3ee679..2fec11bc0ac9 100644
--- a/arch/x86/kvm/vmx/vmx.c
+++ b/arch/x86/kvm/vmx/vmx.c
@@ -7050,10 +7050,9 @@ 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;
 
 	/*
-- 
2.21.0

