> -----Original Message-----
> From: Jason Wang [mailto:jasow...@redhat.com]
> Sent: Friday, August 31, 2012 1:33 AM
> To: de...@linuxdriverproject.org; linux-kernel@vger.kernel.org
> Cc: Jason Wang; KY Srinivasan; Haiyang Zhang
> Subject: [PATCH] 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.
>
> Cc: "K. Y. Srinivasan" <k...@microsoft.com>
> Cc: Haiyang Zhang <haiya...@microsoft.com>
> Signed-off-by: Jason Wang <jasow...@redhat.com>
Thanks Jason.
Acked-by: K. Y. Srinivasan <k...@microsoft.com>
> ---
> drivers/hv/vmbus_drv.c | 25 ++-----------------------
> 1 files changed, 2 insertions(+), 23 deletions(-)
>
> diff --git a/drivers/hv/vmbus_drv.c b/drivers/hv/vmbus_drv.c
> index f40dd57..8e1a9ec 100644
> --- a/drivers/hv/vmbus_drv.c
> +++ b/drivers/hv/vmbus_drv.c
> @@ -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);
> --
> 1.7.1
>
>
>
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