hv: fail the probing immediately when we are not in hyperv platform

We wait for about 5 seconds for the success of the hyperv registration even if
we were not in hyperv platform. This is suboptimal, so the patch check the cpuid
in the beginning of hv_acpi_init() instead of in vmbus_bus_init() to fail the
probing immediately.

Signed-off-by: Jason Wang <jasowang@redhat.com>
Cc: Haiyang Zhang <haiyangz@microsoft.com>
Acked-by: K. Y. Srinivasan <kys@microsoft.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/hv/vmbus_drv.c

@@ -719,10 +719,35 @@ static struct acpi_driver vmbus_acpi_driver = {
 	},
 };
 
+/*
+ * query_hypervisor_presence
+ * - Query the cpuid for presence of windows hypervisor
+ */
+static int query_hypervisor_presence(void)
+{
+	unsigned int eax;
+	unsigned int ebx;
+	unsigned int ecx;
+	unsigned int edx;
+	unsigned int op;
+
+	eax = 0;
+	ebx = 0;
+	ecx = 0;
+	edx = 0;
+	op = HVCPUID_VERSION_FEATURES;
+	cpuid(op, &eax, &ebx, &ecx, &edx);
+
+	return ecx & HV_PRESENT_BIT;
+}
+
 static int __init hv_acpi_init(void)
 {
 	int ret, t;
 
+	if (!query_hypervisor_presence())
+		return -ENODEV;
+
 	init_completion(&probe_event);
 
 	/*