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path: root/drivers/hv/vmbus_drv.c
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Diffstat (limited to 'drivers/hv/vmbus_drv.c')
-rw-r--r--drivers/hv/vmbus_drv.c25
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 = {
719 }, 719 },
720}; 720};
721 721
722/*
723 * query_hypervisor_presence
724 * - Query the cpuid for presence of windows hypervisor
725 */
726static int query_hypervisor_presence(void)
727{
728 unsigned int eax;
729 unsigned int ebx;
730 unsigned int ecx;
731 unsigned int edx;
732 unsigned int op;
733
734 eax = 0;
735 ebx = 0;
736 ecx = 0;
737 edx = 0;
738 op = HVCPUID_VERSION_FEATURES;
739 cpuid(op, &eax, &ebx, &ecx, &edx);
740
741 return ecx & HV_PRESENT_BIT;
742}
743
722static int __init hv_acpi_init(void) 744static int __init hv_acpi_init(void)
723{ 745{
724 int ret, t; 746 int ret, t;
725 747
748 if (!query_hypervisor_presence())
749 return -ENODEV;
750
726 init_completion(&probe_event); 751 init_completion(&probe_event);
727 752
728 /* 753 /*