KVM: VMX: Enable and initialize VMX TSC scaling

This patch exhances kvm-intel module to enable VMX TSC scaling and
collects information of TSC scaling ratio during initialization.

Signed-off-by: Haozhong Zhang <[e-mail]>
Signed-off-by: Paolo Bonzini <[e-mail]>

arch/x86/include/asm/vmx.h

···
 #define SECONDARY_EXEC_ENABLE_PML               0x00020000
 #define SECONDARY_EXEC_XSAVES			0x00100000
 #define SECONDARY_EXEC_PCOMMIT			0x00200000
+#define SECONDARY_EXEC_TSC_SCALING              0x02000000
 
 #define PIN_BASED_EXT_INTR_MASK                 0x00000001
 #define PIN_BASED_NMI_EXITING                   0x00000008
···
 	VMWRITE_BITMAP                  = 0x00002028,
 	XSS_EXIT_BITMAP                 = 0x0000202C,
 	XSS_EXIT_BITMAP_HIGH            = 0x0000202D,
+	TSC_MULTIPLIER                  = 0x00002032,
+	TSC_MULTIPLIER_HIGH             = 0x00002033,
 	GUEST_PHYSICAL_ADDRESS          = 0x00002400,
 	GUEST_PHYSICAL_ADDRESS_HIGH     = 0x00002401,
 	VMCS_LINK_POINTER               = 0x00002800,

arch/x86/kvm/vmx.c

···
 static bool __read_mostly enable_pml = 1;
 module_param_named(pml, enable_pml, bool, S_IRUGO);
 
+#define KVM_VMX_TSC_MULTIPLIER_MAX     0xffffffffffffffffULL
+
 #define KVM_GUEST_CR0_MASK (X86_CR0_NW | X86_CR0_CD)
 #define KVM_VM_CR0_ALWAYS_ON_UNRESTRICTED_GUEST (X86_CR0_WP | X86_CR0_NE)
 #define KVM_VM_CR0_ALWAYS_ON						\
···
 static inline bool cpu_has_vmx_pml(void)
 {
 	return vmcs_config.cpu_based_2nd_exec_ctrl & SECONDARY_EXEC_ENABLE_PML;
+}
+
+static inline bool cpu_has_vmx_tsc_scaling(void)
+{
+	return vmcs_config.cpu_based_2nd_exec_ctrl &
+		SECONDARY_EXEC_TSC_SCALING;
 }
 
 static inline bool report_flexpriority(void)
···
 			SECONDARY_EXEC_SHADOW_VMCS |
 			SECONDARY_EXEC_XSAVES |
 			SECONDARY_EXEC_ENABLE_PML |
-			SECONDARY_EXEC_PCOMMIT;
+			SECONDARY_EXEC_PCOMMIT |
+			SECONDARY_EXEC_TSC_SCALING;
 		if (adjust_vmx_controls(min2, opt2,
 					MSR_IA32_VMX_PROCBASED_CTLS2,
 					&_cpu_based_2nd_exec_control) < 0)
···
 
 	if (!cpu_has_vmx_apicv())
 		enable_apicv = 0;
+
+	if (cpu_has_vmx_tsc_scaling()) {
+		kvm_has_tsc_control = true;
+		kvm_max_tsc_scaling_ratio = KVM_VMX_TSC_MULTIPLIER_MAX;
+		kvm_tsc_scaling_ratio_frac_bits = 48;
+	}
 
 	if (enable_apicv)
 		kvm_x86_ops->update_cr8_intercept = NULL;