diff --git a/sys/amd64/include/vmm.h b/sys/amd64/include/vmm.h
--- a/sys/amd64/include/vmm.h
+++ b/sys/amd64/include/vmm.h
@@ -122,33 +122,7 @@
 #define	VM_INTINFO_HWEXCEPTION	(3 << 8)
 #define	VM_INTINFO_SWINTR	(4 << 8)
 
-/*
- * The VM name has to fit into the pathname length constraints of devfs,
- * governed primarily by SPECNAMELEN.  The length is the total number of
- * characters in the full path, relative to the mount point and not
- * including any leading '/' characters.
- * A prefix and a suffix are added to the name specified by the user.
- * The prefix is usually "vmm/" or "vmm.io/", but can be a few characters
- * longer for future use.
- * The suffix is a string that identifies a bootrom image or some similar
- * image that is attached to the VM. A separator character gets added to
- * the suffix automatically when generating the full path, so it must be
- * accounted for, reducing the effective length by 1.
- * The effective length of a VM name is 229 bytes for FreeBSD 13 and 37
- * bytes for FreeBSD 12.  A minimum length is set for safety and supports
- * a SPECNAMELEN as small as 32 on old systems.
- */
-#define VM_MAX_PREFIXLEN 10
-#define VM_MAX_SUFFIXLEN 15
-#define VM_MIN_NAMELEN   6
-#define VM_MAX_NAMELEN \
-    (SPECNAMELEN - VM_MAX_PREFIXLEN - VM_MAX_SUFFIXLEN - 1)
-
 #ifdef _KERNEL
-#include <sys/kassert.h>
-
-CTASSERT(VM_MAX_NAMELEN >= VM_MIN_NAMELEN);
-
 struct vm;
 struct vm_exception;
 struct vm_mem;
diff --git a/sys/amd64/include/vmm_dev.h b/sys/amd64/include/vmm_dev.h
--- a/sys/amd64/include/vmm_dev.h
+++ b/sys/amd64/include/vmm_dev.h
@@ -34,6 +34,8 @@
 #include <machine/vmm.h>
 #include <machine/vmm_snapshot.h>
 
+#include <dev/vmm/vmm_param.h>
+
 struct vm_memmap {
 	vm_paddr_t	gpa;
 	int		segid;		/* memory segment */
diff --git a/sys/amd64/vmm/vmm.c b/sys/amd64/vmm/vmm.c
--- a/sys/amd64/vmm/vmm.c
+++ b/sys/amd64/vmm/vmm.c
@@ -523,10 +523,6 @@
 	struct vm *vm;
 	int error;
 
-	if (name == NULL || strnlen(name, VM_MAX_NAMELEN + 1) ==
-	    VM_MAX_NAMELEN + 1)
-		return (EINVAL);
-
 	vm = malloc(sizeof(struct vm), M_VM, M_WAITOK | M_ZERO);
 	error = vm_mem_init(&vm->mem, 0, VM_MAXUSER_ADDRESS_LA48);
 	if (error != 0) {
diff --git a/sys/arm64/include/vmm.h b/sys/arm64/include/vmm.h
--- a/sys/arm64/include/vmm.h
+++ b/sys/arm64/include/vmm.h
@@ -106,27 +106,6 @@
 
 #define VM_GUEST_BASE_IPA	0x80000000UL	/* Guest kernel start ipa */
 
-/*
- * The VM name has to fit into the pathname length constraints of devfs,
- * governed primarily by SPECNAMELEN.  The length is the total number of
- * characters in the full path, relative to the mount point and not 
- * including any leading '/' characters.
- * A prefix and a suffix are added to the name specified by the user.
- * The prefix is usually "vmm/" or "vmm.io/", but can be a few characters
- * longer for future use.
- * The suffix is a string that identifies a bootrom image or some similar
- * image that is attached to the VM. A separator character gets added to
- * the suffix automatically when generating the full path, so it must be
- * accounted for, reducing the effective length by 1.
- * The effective length of a VM name is 229 bytes for FreeBSD 13 and 37
- * bytes for FreeBSD 12.  A minimum length is set for safety and supports
- * a SPECNAMELEN as small as 32 on old systems.
- */
-#define VM_MAX_PREFIXLEN 10
-#define VM_MAX_SUFFIXLEN 15
-#define VM_MAX_NAMELEN \
-    (SPECNAMELEN - VM_MAX_PREFIXLEN - VM_MAX_SUFFIXLEN - 1)
-
 #ifdef _KERNEL
 struct vm;
 struct vm_exception;
diff --git a/sys/arm64/include/vmm_dev.h b/sys/arm64/include/vmm_dev.h
--- a/sys/arm64/include/vmm_dev.h
+++ b/sys/arm64/include/vmm_dev.h
@@ -31,6 +31,8 @@
 
 #include <machine/vmm.h>
 
+#include <dev/vmm/vmm_param.h>
+
 struct vm_memmap {
 	vm_paddr_t	gpa;
 	int		segid;		/* memory segment */
diff --git a/sys/arm64/vmm/vmm.c b/sys/arm64/vmm/vmm.c
--- a/sys/arm64/vmm/vmm.c
+++ b/sys/arm64/vmm/vmm.c
@@ -124,7 +124,7 @@
 	volatile cpuset_t suspended_cpus; 	/* (i) suspended vcpus */
 	volatile cpuset_t halted_cpus;		/* (x) cpus in a hard halt */
 	struct vm_mem	mem;			/* (i) guest memory */
-	char		name[VM_MAX_NAMELEN];	/* (o) virtual machine name */
+	char		name[VM_MAX_NAMELEN + 1];	/* (o) virtual machine name */
 	struct vcpu	**vcpu;			/* (i) guest vcpus */
 	struct vmm_mmio_region mmio_region[VM_MAX_MMIO_REGIONS];
 						/* (o) guest MMIO regions */
@@ -437,9 +437,6 @@
 	struct vm *vm;
 	int error;
 
-	if (name == NULL || strlen(name) >= VM_MAX_NAMELEN)
-		return (EINVAL);
-
 	vm = malloc(sizeof(struct vm), M_VMM, M_WAITOK | M_ZERO);
 	error = vm_mem_init(&vm->mem, 0, 1ul << 39);
 	if (error != 0) {
diff --git a/sys/dev/vmm/vmm_dev.h b/sys/dev/vmm/vmm_dev.h
--- a/sys/dev/vmm/vmm_dev.h
+++ b/sys/dev/vmm/vmm_dev.h
@@ -11,8 +11,11 @@
 
 #include <sys/types.h>
 #include <sys/ioccom.h>
+
 #include <machine/vmm_dev.h>
 
+#include <dev/vmm/vmm_param.h>
+
 #ifdef _KERNEL
 struct thread;
 struct vm;
diff --git a/sys/dev/vmm/vmm_dev.c b/sys/dev/vmm/vmm_dev.c
--- a/sys/dev/vmm/vmm_dev.c
+++ b/sys/dev/vmm/vmm_dev.c
@@ -984,6 +984,9 @@
 	struct vm *vm;
 	int error;
 
+	if (name == NULL || strlen(name) > VM_MAX_NAMELEN)
+		return (EINVAL);
+
 	sx_xlock(&vmmdev_mtx);
 	sc = vmmdev_lookup(name, cred);
 	if (sc != NULL) {
diff --git a/sys/dev/vmm/vmm_param.h b/sys/dev/vmm/vmm_param.h
new file mode 100644
--- /dev/null
+++ b/sys/dev/vmm/vmm_param.h
@@ -0,0 +1,33 @@
+/*-
+ * SPDX-License-Identifier: BSD-2-Clause
+ *
+ * Copyright (c) 2011 NetApp, Inc.
+ * All rights reserved.
+ */
+
+#ifndef _DEV_VMM_PARAM_H_
+#define	_DEV_VMM_PARAM_H_
+
+/*
+ * The VM name has to fit into the pathname length constraints of devfs,
+ * governed primarily by SPECNAMELEN.  The length is the total number of
+ * characters in the full path, relative to the mount point and not
+ * including any leading '/' characters.
+ * A prefix and a suffix are added to the name specified by the user.
+ * The prefix is usually "vmm/" or "vmm.io/", but can be a few characters
+ * longer for future use.
+ * The suffix is a string that identifies a bootrom image or some similar
+ * image that is attached to the VM. A separator character gets added to
+ * the suffix automatically when generating the full path, so it must be
+ * accounted for, reducing the effective length by 1.
+ * The effective length of a VM name is 229 bytes for FreeBSD 13 and 37
+ * bytes for FreeBSD 12.  A minimum length is set for safety and supports
+ * a SPECNAMELEN as small as 32 on old systems.
+ */
+#define	VM_MAX_PREFIXLEN	10
+#define	VM_MAX_SUFFIXLEN	15
+#define	VM_MIN_NAMELEN		6
+#define	VM_MAX_NAMELEN		\
+	(SPECNAMELEN - VM_MAX_PREFIXLEN - VM_MAX_SUFFIXLEN - 1)
+
+#endif /* !_DEV_VMM_PARAM_H_ */
diff --git a/sys/riscv/include/vmm.h b/sys/riscv/include/vmm.h
--- a/sys/riscv/include/vmm.h
+++ b/sys/riscv/include/vmm.h
@@ -103,9 +103,6 @@
 #define	VM_INTINFO_HWEXCEPTION	(3 << 8)
 #define	VM_INTINFO_SWINTR	(4 << 8)
 
-#define	VM_MAX_NAMELEN	32
-#define VM_MAX_SUFFIXLEN 15
-
 #ifdef _KERNEL
 
 struct vm;
diff --git a/sys/riscv/include/vmm_dev.h b/sys/riscv/include/vmm_dev.h
--- a/sys/riscv/include/vmm_dev.h
+++ b/sys/riscv/include/vmm_dev.h
@@ -38,6 +38,8 @@
 
 #include <machine/vmm.h>
 
+#include <dev/vmm/vmm_param.h>
+
 struct vm_memmap {
 	vm_paddr_t	gpa;
 	int		segid;		/* memory segment */
diff --git a/sys/riscv/vmm/vmm.c b/sys/riscv/vmm/vmm.c
--- a/sys/riscv/vmm/vmm.c
+++ b/sys/riscv/vmm/vmm.c
@@ -120,7 +120,7 @@
 	volatile cpuset_t suspended_cpus; 	/* (i) suspended vcpus */
 	volatile cpuset_t halted_cpus;		/* (x) cpus in a hard halt */
 	struct vm_mem	mem;			/* (i) [m+v] guest memory */
-	char		name[VM_MAX_NAMELEN];	/* (o) virtual machine name */
+	char		name[VM_MAX_NAMELEN + 1]; /* (o) virtual machine name */
 	struct vcpu	**vcpu;			/* (i) guest vcpus */
 	struct vmm_mmio_region mmio_region[VM_MAX_MMIO_REGIONS];
 						/* (o) guest MMIO regions */
@@ -311,9 +311,6 @@
 	struct vm *vm;
 	int error;
 
-	if (name == NULL || strlen(name) >= VM_MAX_NAMELEN)
-		return (EINVAL);
-
 	vm = malloc(sizeof(struct vm), M_VMM, M_WAITOK | M_ZERO);
 	error = vm_mem_init(&vm->mem, 0, 1ul << 39);
 	if (error != 0) {