Index: sys/dev/hyperv/include/hyperv.h
===================================================================
--- sys/dev/hyperv/include/hyperv.h
+++ sys/dev/hyperv/include/hyperv.h
@@ -36,6 +36,9 @@
 #include <vm/vm.h>
 #include <vm/pmap.h>
 
+#define VM_GUEST_IS_HYPERV	\
+	(vm_guest == VM_GUEST_HV || vm_guest == VM_GUEST_HV_SCSI)
+
 struct hyperv_guid {
 	uint8_t		hv_guid[16];
 } __packed;
Index: sys/dev/hyperv/stordisengage/hv_ata_pci_disengage.c
===================================================================
--- sys/dev/hyperv/stordisengage/hv_ata_pci_disengage.c
+++ sys/dev/hyperv/stordisengage/hv_ata_pci_disengage.c
@@ -73,6 +73,7 @@
 #include <dev/pci/pcireg.h>
 #include <dev/ata/ata-all.h>
 #include <dev/ata/ata-pci.h>
+#include <dev/hyperv/include/hyperv.h>
 #include <ata_if.h>
 
 /* prototypes */
@@ -94,7 +95,7 @@
 	/*
 	 * Don't probe if not running in a Hyper-V environment
 	 */
-	if (vm_guest != VM_GUEST_HV)
+	if (!VM_GUEST_IS_HYPERV)
 		return (ENXIO);
 
 	if (device_get_unit(parent) != 0 || device_get_ivars(dev) != 0)
Index: sys/dev/hyperv/storvsc/hv_storvsc_drv_freebsd.c
===================================================================
--- sys/dev/hyperv/storvsc/hv_storvsc_drv_freebsd.c
+++ sys/dev/hyperv/storvsc/hv_storvsc_drv_freebsd.c
@@ -2325,3 +2325,14 @@
 		return DRIVER_STORVSC;
 	return DRIVER_UNKNOWN;
 }
+
+static void
+storvsc_ident(void *arg __unused)
+{
+	if (vm_guest != VM_GUEST_HV)
+		return;
+	/* Enlightened SCSI driver is going to take over disks. */
+	vm_guest = VM_GUEST_HV_SCSI;
+}
+/* SI_ORDER_SECOND - MUST after Hypercall creation */
+SYSINIT(storvsc_ident, SI_SUB_DRIVERS, SI_ORDER_SECOND, storvsc_ident, NULL);
Index: sys/dev/hyperv/vmbus/vmbus.c
===================================================================
--- sys/dev/hyperv/vmbus/vmbus.c
+++ sys/dev/hyperv/vmbus/vmbus.c
@@ -996,7 +996,7 @@
 	char *id[] = { "VMBUS", NULL };
 
 	if (ACPI_ID_PROBE(device_get_parent(dev), dev, id) == NULL ||
-	    device_get_unit(dev) != 0 || vm_guest != VM_GUEST_HV ||
+	    device_get_unit(dev) != 0 || !VM_GUEST_IS_HYPERV ||
 	    (hyperv_features & CPUID_HV_MSR_SYNIC) == 0)
 		return (ENXIO);
 
@@ -1177,7 +1177,7 @@
 {
 	struct vmbus_softc *sc = vmbus_get_softc();
 
-	if (vm_guest != VM_GUEST_HV || sc == NULL)
+	if (!VM_GUEST_IS_HYPERV || sc == NULL)
 		return;
 
 	/* 
Index: sys/kern/subr_param.c
===================================================================
--- sys/kern/subr_param.c
+++ sys/kern/subr_param.c
@@ -149,6 +149,7 @@
 	"hv",
 	"vmware",
 	"kvm",
+	"hv",		/* Hyper-V w/ SCSI driver */
 	NULL
 };
 CTASSERT(nitems(vm_guest_sysctl_names) - 1 == VM_LAST);
Index: sys/sys/systm.h
===================================================================
--- sys/sys/systm.h
+++ sys/sys/systm.h
@@ -74,7 +74,7 @@
  * Keep in sync with vm_guest_sysctl_names[].
  */
 enum VM_GUEST { VM_GUEST_NO = 0, VM_GUEST_VM, VM_GUEST_XEN, VM_GUEST_HV,
-		VM_GUEST_VMWARE, VM_GUEST_KVM, VM_LAST };
+		VM_GUEST_VMWARE, VM_GUEST_KVM, VM_GUEST_HV_SCSI, VM_LAST };
 
 #if defined(WITNESS) || defined(INVARIANT_SUPPORT)
 void	kassert_panic(const char *fmt, ...)  __printflike(1, 2);