* [PATCH] hv: vmbus_drv: detect hyperv through x86_hyper
@ 2012-08-31 5:32 Jason Wang
2012-08-31 15:14 ` KY Srinivasan
0 siblings, 1 reply; 2+ messages in thread
From: Jason Wang @ 2012-08-31 5:32 UTC (permalink / raw)
To: devel, linux-kernel; +Cc: Jason Wang, K. Y. Srinivasan, Haiyang Zhang
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" <kys@microsoft.com>
Cc: Haiyang Zhang <haiyangz@microsoft.com>
Signed-off-by: Jason Wang <jasowang@redhat.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
^ permalink raw reply related [flat|nested] 2+ messages in thread
* RE: [PATCH] hv: vmbus_drv: detect hyperv through x86_hyper
2012-08-31 5:32 [PATCH] hv: vmbus_drv: detect hyperv through x86_hyper Jason Wang
@ 2012-08-31 15:14 ` KY Srinivasan
0 siblings, 0 replies; 2+ messages in thread
From: KY Srinivasan @ 2012-08-31 15:14 UTC (permalink / raw)
To: Jason Wang, devel, linux-kernel, Greg KH (gregkh@linuxfoundation.org)
Cc: Haiyang Zhang
> -----Original Message-----
> From: Jason Wang [mailto:jasowang@redhat.com]
> Sent: Friday, August 31, 2012 1:33 AM
> To: devel@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" <kys@microsoft.com>
> Cc: Haiyang Zhang <haiyangz@microsoft.com>
> Signed-off-by: Jason Wang <jasowang@redhat.com>
Thanks Jason.
Acked-by: K. Y. Srinivasan <kys@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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