KVM: VMX: Add parameter to control A/D bits support, default is on

Add kernel parameter to control A/D bits support, it's on by default.
Signed-off-by: Haitao Shan <haitao.shan@intel.com>
Signed-off-by: Xudong Hao <xudong.hao@intel.com>
Signed-off-by: Avi Kivity <avi@redhat.com>

arch/x86/kvm/vmx.c

@@ -71,6 +71,9 @@ static bool __read_mostly enable_unrestricted_guest = 1;
 module_param_named(unrestricted_guest,
 			enable_unrestricted_guest, bool, S_IRUGO);
 
+static bool __read_mostly enable_ept_ad_bits = 1;
+module_param_named(eptad, enable_ept_ad_bits, bool, S_IRUGO);
+
 static bool __read_mostly emulate_invalid_guest_state = 0;
 module_param(emulate_invalid_guest_state, bool, S_IRUGO);
 
@@ -789,6 +792,11 @@ static inline bool cpu_has_vmx_ept_4levels(void)
 	return vmx_capability.ept & VMX_EPT_PAGE_WALK_4_BIT;
 }
 
+static inline bool cpu_has_vmx_ept_ad_bits(void)
+{
+	return vmx_capability.ept & VMX_EPT_AD_BIT;
+}
+
 static inline bool cpu_has_vmx_invept_individual_addr(void)
 {
 	return vmx_capability.ept & VMX_EPT_EXTENT_INDIVIDUAL_BIT;
@@ -2645,8 +2653,12 @@ static __init int hardware_setup(void)
 	    !cpu_has_vmx_ept_4levels()) {
 		enable_ept = 0;
 		enable_unrestricted_guest = 0;
+		enable_ept_ad_bits = 0;
 	}
 
+	if (!cpu_has_vmx_ept_ad_bits())
+		enable_ept_ad_bits = 0;
+
 	if (!cpu_has_vmx_unrestricted_guest())
 		enable_unrestricted_guest = 0;