KVM: VMX: Setup TSC scaling ratio when a vcpu is loaded

This patch makes kvm-intel module to load TSC scaling ratio into TSC
multiplier field of VMCS when a vcpu is loaded, so that TSC scaling
ratio can take effect if VMX TSC scaling is enabled.
Signed-off-by: Haozhong Zhang <haozhong.zhang@intel.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

arch/x86/kvm/vmx.c

@@ -2061,6 +2061,12 @@ static void vmx_vcpu_load(struct kvm_vcpu *vcpu, int cpu)
 
 		rdmsrl(MSR_IA32_SYSENTER_ESP, sysenter_esp);
 		vmcs_writel(HOST_IA32_SYSENTER_ESP, sysenter_esp); /* 22.2.3 */
+
+		/* Setup TSC multiplier */
+		if (cpu_has_vmx_tsc_scaling())
+			vmcs_write64(TSC_MULTIPLIER,
+				     vcpu->arch.tsc_scaling_ratio);
+
 		vmx->loaded_vmcs->cpu = cpu;
 	}