diff --git a/xen/arch/x86/traps.c b/xen/arch/x86/traps.c
index e44cd2db19..318153ad99 100644
--- a/xen/arch/x86/traps.c
+++ b/xen/arch/x86/traps.c
@@ -873,6 +873,7 @@ void pv_cpuid(struct cpu_user_regs *regs)
         __clear_bit(X86_FEATURE_LWP % 32, &c);
         __clear_bit(X86_FEATURE_NODEID_MSR % 32, &c);
         __clear_bit(X86_FEATURE_TOPOEXT % 32, &c);
+        __clear_bit(X86_FEATURE_MWAITX % 32, &c);
         break;
 
     case 0x00000005: /* MONITOR/MWAIT */
diff --git a/xen/include/asm-x86/cpufeature.h b/xen/include/asm-x86/cpufeature.h
index 526821f42c..d36bbca637 100644
--- a/xen/include/asm-x86/cpufeature.h
+++ b/xen/include/asm-x86/cpufeature.h
@@ -137,6 +137,7 @@
 #define X86_FEATURE_NODEID_MSR  (6*32+19) /* NodeId MSR */
 #define X86_FEATURE_TBM         (6*32+21) /* trailing bit manipulations */
 #define X86_FEATURE_TOPOEXT     (6*32+22) /* topology extensions CPUID leafs */
+#define X86_FEATURE_MWAITX      (6*32+29) /* MWAIT extension (MONITORX/MWAITX) */
 
 /* Intel-defined CPU features, CPUID level 0x00000007:0 (ebx), word 7 */
 #define X86_FEATURE_FSGSBASE	(7*32+ 0) /* {RD,WR}{FS,GS}BASE instructions */