KVM: x86: Move TSC scaling logic out of call-back read_l1_tsc()

Both VMX and SVM scales the host TSC in the same way in call-back
read_l1_tsc(), so this patch moves the scaling logic from call-back
read_l1_tsc() to a common function kvm_read_l1_tsc().
Signed-off-by: Haozhong Zhang <haozhong.zhang@intel.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

arch/x86/include/asm/kvm_host.h

@@ -1226,6 +1226,7 @@ void kvm_define_shared_msr(unsigned index, u32 msr);
 int kvm_set_shared_msr(unsigned index, u64 val, u64 mask);
 
 u64 kvm_scale_tsc(struct kvm_vcpu *vcpu, u64 tsc);
+u64 kvm_read_l1_tsc(struct kvm_vcpu *vcpu, u64 host_tsc);
 
 unsigned long kvm_get_linear_rip(struct kvm_vcpu *vcpu);
 bool kvm_is_linear_rip(struct kvm_vcpu *vcpu, unsigned long linear_rip);

arch/x86/kvm/lapic.c

@@ -1250,7 +1250,7 @@ void wait_lapic_expire(struct kvm_vcpu *vcpu)
 
 	tsc_deadline = apic->lapic_timer.expired_tscdeadline;
 	apic->lapic_timer.expired_tscdeadline = 0;
-	guest_tsc = kvm_x86_ops->read_l1_tsc(vcpu, rdtsc());
+	guest_tsc = kvm_read_l1_tsc(vcpu, rdtsc());
 	trace_kvm_wait_lapic_expire(vcpu->vcpu_id, guest_tsc - tsc_deadline);
 
 	/* __delay is delay_tsc whenever the hardware has TSC, thus always.  */
@@ -1318,7 +1318,7 @@ static void start_apic_timer(struct kvm_lapic *apic)
 		local_irq_save(flags);
 
 		now = apic->lapic_timer.timer.base->get_time();
-		guest_tsc = kvm_x86_ops->read_l1_tsc(vcpu, rdtsc());
+		guest_tsc = kvm_read_l1_tsc(vcpu, rdtsc());
 		if (likely(tscdeadline > guest_tsc)) {
 			ns = (tscdeadline - guest_tsc) * 1000000ULL;
 			do_div(ns, this_tsc_khz);

arch/x86/kvm/svm.c

@@ -2984,8 +2984,7 @@ static int cr8_write_interception(struct vcpu_svm *svm)
 static u64 svm_read_l1_tsc(struct kvm_vcpu *vcpu, u64 host_tsc)
 {
 	struct vmcb *vmcb = get_host_vmcb(to_svm(vcpu));
-	return vmcb->control.tsc_offset +
-		kvm_scale_tsc(vcpu, host_tsc);
+	return vmcb->control.tsc_offset + host_tsc;
 }
 
 static int svm_get_msr(struct kvm_vcpu *vcpu, struct msr_data *msr_info)

arch/x86/kvm/x86.c

@@ -1401,6 +1401,12 @@ static u64 kvm_compute_tsc_offset(struct kvm_vcpu *vcpu, u64 target_tsc)
 	return target_tsc - tsc;
 }
 
+u64 kvm_read_l1_tsc(struct kvm_vcpu *vcpu, u64 host_tsc)
+{
+	return kvm_x86_ops->read_l1_tsc(vcpu, kvm_scale_tsc(vcpu, host_tsc));
+}
+EXPORT_SYMBOL_GPL(kvm_read_l1_tsc);
+
 void kvm_write_tsc(struct kvm_vcpu *vcpu, struct msr_data *msr)
 {
 	struct kvm *kvm = vcpu->kvm;
@@ -1738,7 +1744,7 @@ static int kvm_guest_time_update(struct kvm_vcpu *v)
 		kernel_ns = get_kernel_ns();
 	}
 
-	tsc_timestamp = kvm_x86_ops->read_l1_tsc(v, host_tsc);
+	tsc_timestamp = kvm_read_l1_tsc(v, host_tsc);
 
 	/*
 	 * We may have to catch up the TSC to match elapsed wall clock
@@ -6545,8 +6551,7 @@ static int vcpu_enter_guest(struct kvm_vcpu *vcpu)
 	if (hw_breakpoint_active())
 		hw_breakpoint_restore();
 
-	vcpu->arch.last_guest_tsc = kvm_x86_ops->read_l1_tsc(vcpu,
-							   rdtsc());
+	vcpu->arch.last_guest_tsc = kvm_read_l1_tsc(vcpu, rdtsc());
 
 	vcpu->mode = OUTSIDE_GUEST_MODE;
 	smp_wmb();