Staging: hv: match on DMI values to know if we should run.

The HV core mucks around with specific irqs and other low-level stuff
and takes forever to determine that it really shouldn't be running on a
machine.  So instead, trigger off of the DMI system information and
error out much sooner.  This also allows the module loading tools to
recognize that this code should be loaded on this type of system.

Cc: Haiyang Zhang <haiyangz@microsoft.com>
Cc: Hank Janssen <hjanssen@microsoft.com>
Cc: stable <stable@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

drivers/staging/hv/vmbus_drv.c

@@ -25,6 +25,7 @@
 #include <linux/interrupt.h>
 #include <linux/sysctl.h>
 #include <linux/pci.h>
+#include <linux/dmi.h>
 #include "VersionInfo.h"
 #include "osd.h"
 #include "logging.h"
@@ -948,6 +949,19 @@ static irqreturn_t vmbus_isr(int irq, void *dev_id)
 	}
 }
 
+static struct dmi_system_id __initdata microsoft_hv_dmi_table[] = {
+	{
+		.ident = "Hyper-V",
+		.matches = {
+			DMI_MATCH(DMI_SYS_VENDOR, "Microsoft Corporation"),
+			DMI_MATCH(DMI_PRODUCT_NAME, "Virtual Machine"),
+			DMI_MATCH(DMI_BOARD_NAME, "Virtual Machine"),
+		},
+	},
+	{ },
+};
+MODULE_DEVICE_TABLE(dmi, microsoft_hv_dmi_table);
+
 static int __init vmbus_init(void)
 {
 	int ret = 0;
@@ -959,6 +973,9 @@ static int __init vmbus_init(void)
 		vmbus_loglevel, HIWORD(vmbus_loglevel), LOWORD(vmbus_loglevel));
 	/* Todo: it is used for loglevel, to be ported to new kernel. */
 
+	if (!dmi_check_system(microsoft_hv_dmi_table))
+		return -ENODEV;
+
 	ret = vmbus_bus_init(VmbusInitialize);
 
 	DPRINT_EXIT(VMBUS_DRV);
@@ -980,10 +997,6 @@ static void __exit vmbus_exit(void)
  * needed by distro tools to determine if the hyperv drivers should be
  * installed and/or configured.  We don't do anything else with the table, but
  * it needs to be present.
- *
- * We might consider triggering off of DMI table info as well, as that does
- * decribe the virtual machine being run on, but not all configuration tools
- * seem to be able to handle DMI device ids properly.
  */
 const static struct pci_device_id microsoft_hv_pci_table[] = {
 	{ PCI_DEVICE(0x1414, 0x5353) },	/* VGA compatible controller */