Index: head/sys/amd64/vmm/vmm_dev.c
===================================================================
--- head/sys/amd64/vmm/vmm_dev.c
+++ head/sys/amd64/vmm/vmm_dev.c
@@ -33,6 +33,7 @@
 
 #include <sys/param.h>
 #include <sys/kernel.h>
+#include <sys/jail.h>
 #include <sys/queue.h>
 #include <sys/lock.h>
 #include <sys/mutex.h>
@@ -43,6 +44,7 @@
 #include <sys/ioccom.h>
 #include <sys/mman.h>
 #include <sys/uio.h>
+#include <sys/proc.h>
 
 #include <vm/vm.h>
 #include <vm/pmap.h>
@@ -82,16 +84,29 @@
 
 static SLIST_HEAD(, vmmdev_softc) head;
 
+static unsigned pr_allow_flag;
 static struct mtx vmmdev_mtx;
 
 static MALLOC_DEFINE(M_VMMDEV, "vmmdev", "vmmdev");
 
 SYSCTL_DECL(_hw_vmm);
 
+static int vmm_priv_check(struct ucred *ucred);
 static int devmem_create_cdev(const char *vmname, int id, char *devmem);
 static void devmem_destroy(void *arg);
 
 static int
+vmm_priv_check(struct ucred *ucred)
+{
+
+	if (jailed(ucred) &&
+	    !(ucred->cr_prison->pr_allow & pr_allow_flag))
+		return (EPERM);
+
+	return (0);
+}
+
+static int
 vcpu_lock_one(struct vmmdev_softc *sc, int vcpu)
 {
 	int error;
@@ -177,6 +192,10 @@
 	void *hpa, *cookie;
 	struct vmmdev_softc *sc;
 
+	error = vmm_priv_check(curthread->td_ucred);
+	if (error)
+		return (error);
+
 	sc = vmmdev_lookup2(cdev);
 	if (sc == NULL)
 		return (ENXIO);
@@ -351,11 +370,14 @@
 	uint64_t *regvals;
 	int *regnums;
 
+	error = vmm_priv_check(curthread->td_ucred);
+	if (error)
+		return (error);
+
 	sc = vmmdev_lookup2(cdev);
 	if (sc == NULL)
 		return (ENXIO);
 
-	error = 0;
 	vcpu = -1;
 	state_changed = 0;
 
@@ -777,6 +799,10 @@
 	int error, found, segid;
 	bool sysmem;
 
+	error = vmm_priv_check(curthread->td_ucred);
+	if (error)
+		return (error);
+
 	first = *offset;
 	last = first + mapsize;
 	if ((nprot & PROT_EXEC) || first < 0 || first >= last)
@@ -865,6 +891,10 @@
 	struct vmmdev_softc *sc;
 	struct cdev *cdev;
 
+	error = vmm_priv_check(req->td->td_ucred);
+	if (error)
+		return (error);
+
 	strlcpy(buf, "beavis", sizeof(buf));
 	error = sysctl_handle_string(oidp, buf, sizeof(buf), req);
 	if (error != 0 || req->newptr == NULL)
@@ -906,7 +936,8 @@
 	destroy_dev_sched_cb(cdev, vmmdev_destroy, sc);
 	return (0);
 }
-SYSCTL_PROC(_hw_vmm, OID_AUTO, destroy, CTLTYPE_STRING | CTLFLAG_RW,
+SYSCTL_PROC(_hw_vmm, OID_AUTO, destroy,
+	    CTLTYPE_STRING | CTLFLAG_RW | CTLFLAG_PRISON,
 	    NULL, 0, sysctl_vmm_destroy, "A", NULL);
 
 static struct cdevsw vmmdevsw = {
@@ -927,6 +958,10 @@
 	struct vmmdev_softc *sc, *sc2;
 	char buf[VM_MAX_NAMELEN];
 
+	error = vmm_priv_check(req->td->td_ucred);
+	if (error)
+		return (error);
+
 	strlcpy(buf, "beavis", sizeof(buf));
 	error = sysctl_handle_string(oidp, buf, sizeof(buf), req);
 	if (error != 0 || req->newptr == NULL)
@@ -977,13 +1012,16 @@
 
 	return (0);
 }
-SYSCTL_PROC(_hw_vmm, OID_AUTO, create, CTLTYPE_STRING | CTLFLAG_RW,
+SYSCTL_PROC(_hw_vmm, OID_AUTO, create,
+	    CTLTYPE_STRING | CTLFLAG_RW | CTLFLAG_PRISON,
 	    NULL, 0, sysctl_vmm_create, "A", NULL);
 
 void
 vmmdev_init(void)
 {
 	mtx_init(&vmmdev_mtx, "vmm device mutex", NULL, MTX_DEF);
+	pr_allow_flag = prison_add_allow(NULL, "vmm", NULL,
+	    "Allow use of vmm in a jail.");
 }
 
 int
Index: head/usr.sbin/jail/jail.8
===================================================================
--- head/usr.sbin/jail/jail.8
+++ head/usr.sbin/jail/jail.8
@@ -25,7 +25,7 @@
 .\"
 .\" $FreeBSD$
 .\"
-.Dd July 29, 2018
+.Dd July 30, 2018
 .Dt JAIL 8
 .Os
 .Sh NAME
@@ -650,6 +650,12 @@
 .Xr zfs 8
 for information on how to configure the ZFS filesystem to operate from
 within a jail.
+.It Va allow.vmm
+The jail may access
+.Xr vmm 4 .
+This flag is only available when the
+.Xr vmm 4
+kernel module is loaded.
 .It Va linux
 Determine how a jail's Linux emulation environment appears.
 A value of
@@ -1294,6 +1300,7 @@
 .Xr ps 1 ,
 .Xr quota 1 ,
 .Xr jail_set 2 ,
+.Xr vmm 4 ,
 .Xr devfs 5 ,
 .Xr fdescfs 5 ,
 .Xr jail.conf 5 ,