Centralize the detection logic for the Hyper-V hypervisor.

Submitted by:	Roger Pau Monné
Sponsored by:	Citrix Systems R&D
Reviewed by:	gibbs, grehan
Approved by:	re (gjb)

sys/sys/systm.h:
 * Add a new VM_GUEST type, VM_GUEST_HV (HyperV guest).

sys/dev/hyperv/vmbus/hv_vmbus_drv_freebsd.c:
sys/dev/hyperv/vmbus/hv_hv.c:
sys/dev/hyperv/stordisengage/hv_ata_pci_disengage.c:
 * Set vm_guest to VM_GUEST_HV and use that on other HyperV related
   devices instead of cloning the cpuid hypervisor check.
 * Cleanup the vmbus_identify function.

sys/dev/hyperv/stordisengage/hv_ata_pci_disengage.c

@@ -75,17 +75,11 @@ __FBSDID("$FreeBSD$");
 #include <dev/ata/ata-pci.h>
 #include <ata_if.h>
 
-#define HV_X64_MSR_GUEST_OS_ID	0x40000000
-#define HV_X64_CPUID_MIN	0x40000005
-#define HV_X64_CPUID_MAX	0x4000ffff
-
 /* prototypes */
 static int hv_ata_pci_probe(device_t dev);
 static int hv_ata_pci_attach(device_t dev);
 static int hv_ata_pci_detach(device_t dev);
 
-static int hv_check_for_hyper_v(void);
-
 /*
  * generic PCI ATA device probe
  */
@@ -100,7 +94,7 @@ hv_ata_pci_probe(device_t dev)
 	/*
 	 * Don't probe if not running in a Hyper-V environment
 	 */
-	if (!hv_check_for_hyper_v())
+	if (vm_guest != VM_GUEST_HV)
 		return (ENXIO);
 
 	if (device_get_unit(parent) != 0 || device_get_ivars(dev) != 0)
@@ -139,33 +133,6 @@ hv_ata_pci_detach(device_t dev)
 	return (0);
 }
 
-/**
-* Detect Hyper-V and enable fast IDE
-* via enlighted storage driver
-*/
-static int
-hv_check_for_hyper_v(void)
-{
-	u_int regs[4];
-	int hyper_v_detected;
-
-	hyper_v_detected = 0;
-	do_cpuid(1, regs);
-	if (regs[2] & 0x80000000) {
-		/*
-		 * if(a hypervisor is detected)
-		 *  make sure this really is Hyper-V
-		 */
-		do_cpuid(HV_X64_MSR_GUEST_OS_ID, regs);
-		hyper_v_detected =
-			regs[0] >= HV_X64_CPUID_MIN &&
-			regs[0] <= HV_X64_CPUID_MAX &&
-			!memcmp("Microsoft Hv", &regs[1], 12);
-	}
-
-	return (hyper_v_detected);
-}
-
 static device_method_t hv_ata_pci_methods[] = {
 	/* device interface */
 	DEVMETHOD(device_probe,	hv_ata_pci_probe),

sys/dev/hyperv/vmbus/hv_hv.c

@@ -218,7 +218,7 @@ hv_vmbus_init(void)
 	    0,
 	    sizeof(hv_vmbus_handle) * MAXCPU);
 
-	if (!hv_vmbus_query_hypervisor_presence())
+	if (vm_guest != VM_GUEST_HV)
 	    goto cleanup;
 
 	max_leaf = hv_vmbus_get_hypervisor_version();

sys/dev/hyperv/vmbus/hv_vmbus_drv_freebsd.c

@@ -295,11 +295,15 @@ hv_vmbus_child_device_unregister(struct hv_device *child_dev)
 	return(ret);
 }
 
-static void vmbus_identify(driver_t *driver, device_t parent) {
+static void
+vmbus_identify(driver_t *driver, device_t parent)
+{
+	if (!hv_vmbus_query_hypervisor_presence())
+		return;
+
+	vm_guest = VM_GUEST_HV;
+
 	BUS_ADD_CHILD(parent, 0, "vmbus", 0);
-	if (device_find_child(parent, "vmbus", 0) == NULL) {
-		BUS_ADD_CHILD(parent, 0, "vmbus", 0);
-	}
 }
 
 static int
@@ -307,9 +311,6 @@ vmbus_probe(device_t dev) {
 	if(bootverbose)
 		device_printf(dev, "VMBUS: probe\n");
 
-	if (!hv_vmbus_query_hypervisor_presence())
-		return (ENXIO);
-
 	device_set_desc(dev, "Vmbus Devices");
 
 	return (0);
@@ -491,10 +492,13 @@ vmbus_attach(device_t dev)
 static void
 vmbus_init(void)
 {
+	if (vm_guest != VM_GUEST_HV)
+		return;
+
 	/* 
 	 * If the system has already booted and thread
-	 * scheduling is possible indicated by the global
+	 * scheduling is possible, as indicated by the
-	 * cold set to zero, we just call the driver
+	 * global cold set to zero, we just call the driver
 	 * initialization directly.
 	 */
 	if (!cold) 

sys/sys/systm.h

@@ -71,7 +71,7 @@ extern int vm_guest;		/* Running as virtual machine guest? */
  * and/or add to the VM_GUEST_VM type if specific VM functionality is
  * ever implemented (e.g. vendor-specific paravirtualization features).
  */
-enum VM_GUEST { VM_GUEST_NO = 0, VM_GUEST_VM, VM_GUEST_XEN };
+enum VM_GUEST { VM_GUEST_NO = 0, VM_GUEST_VM, VM_GUEST_XEN, VM_GUEST_HV };
 
 #if defined(WITNESS) || defined(INVARIANTS)
 void	kassert_panic(const char *fmt, ...)  __printflike(1, 2);