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hv: vmbus_drv: detect hyperv through x86_hyper 

There are two reasons we need to use x86_hyper instead of
query_hypervisor_presence():

- Not only hyperv but also other hypervisors such as kvm would set
  X86_FEATURE_HYTPERVISOR, so query_hypervisor_presence() will return true even
  in kvm. This may cause extra delay of 5 seconds before failing the probing in
  kvm guest.
- The hypervisor has been detected in init_hypervisor(), so no need to do the
  work again.

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>
This commit is contained in:
Jason Wang 2012-08-31 13:32:44 +08:00 committed by Greg Kroah-Hartman
parent 82aceae4f0
commit 1f94ea8181
1 changed files with 2 additions and 23 deletions
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25
drivers/hv/vmbus_drv.c
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@ -34,6 +34,7 @@
#include <linux/completion.h>
#include <linux/hyperv.h>
#include <asm/hyperv.h>
#include <asm/hypervisor.h>
#include "hyperv_vmbus.h"
@ -719,33 +720,11 @@ 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())
if (x86_hyper != &x86_hyper_ms_hyperv)
return -ENODEV;
init_completion(&probe_event);