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>

1 files changed, 25 insertions, 0 deletions

diff --git a/drivers/hv/vmbus_drv.c b/drivers/hv/vmbus_drv.c
index b76e8b321266..f40dd57bbec1 100644
--- a/drivers/hv/vmbus_drv.c
+++ b/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);
 
         /*