diff --git a/sys/x86/include/specialreg.h b/sys/x86/include/specialreg.h
index efaa1dadb6f7..ccd924e5a958 100644
--- a/sys/x86/include/specialreg.h
+++ b/sys/x86/include/specialreg.h
@@ -427,6 +427,7 @@
  */
 #define	CPUID_STDEXT3_IBPB	0x04000000
 #define	CPUID_STDEXT3_STIBP	0x08000000
+#define	CPUID_STDEXT3_L1D_FLUSH	0x10000000
 #define	CPUID_STDEXT3_ARCH_CAP	0x20000000
 #define	CPUID_STDEXT3_SSBD	0x80000000
 
@@ -478,6 +479,7 @@
 #define	MSR_IA32_EXT_CONFIG	0x0ee	/* Undocumented. Core Solo/Duo only */
 #define	MSR_MTRRcap		0x0fe
 #define	MSR_IA32_ARCH_CAP	0x10a
+#define	MSR_IA32_FLUSH_CMD	0x10b
 #define	MSR_BBL_CR_ADDR		0x116
 #define	MSR_BBL_CR_DECC		0x118
 #define	MSR_BBL_CR_CTL		0x119
@@ -711,6 +713,9 @@
 /* MSR IA32_PRED_CMD */
 #define	IA32_PRED_CMD_IBPB_BARRIER	0x0000000000000001ULL
 
+/* MSR IA32_FLUSH_CMD */
+#define	IA32_FLUSH_CMD_L1D	0x00000001
+
 /*
  * PAT modes.
  */