[PATCH] hv: fail the probing immediately when we are not in hyperv platform

[PATCH] hv: fail the probing immediately when we are not in hyperv platform

[Jason Wang]

We wait for about 5 seconds for the success of the hyperv registration even if
we were not in hyperv platform. This is suboptimal, so the patch check the cpuid
in the beginning of hv_acpi_init() instead of in vmbus_bus_init() to fail the
probing immediately.

Cc: "K. Y. Srinivasan" <kys@microsoft.com>
Cc: Haiyang Zhang <haiyangz@microsoft.com>
Signed-off-by: Jason Wang <jasowang@redhat.com>
---
 drivers/hv/hv.c        |   25 -------------------------
 drivers/hv/vmbus_drv.c |   25 +++++++++++++++++++++++++
 2 files changed, 25 insertions(+), 25 deletions(-)

diff --git a/drivers/hv/hv.c b/drivers/hv/hv.c
index 86f8885..a18ee5d 100644
--- a/drivers/hv/hv.c
+++ b/drivers/hv/hv.c
@@ -38,28 +38,6 @@ struct hv_context hv_context = {
 };
 
 /*
- * 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;
-}
-
-/*
  * query_hypervisor_info - Get version info of the windows hypervisor
  */
 static int query_hypervisor_info(void)
@@ -159,9 +137,6 @@ int hv_init(void)
 	memset(hv_context.synic_message_page, 0,
 	       sizeof(void *) * NR_CPUS);
 
-	if (!query_hypervisor_presence())
-		goto cleanup;
-
 	max_leaf = query_hypervisor_info();
 
 	/* Write our OS info */
diff --git a/drivers/hv/vmbus_drv.c b/drivers/hv/vmbus_drv.c
index 4748086..a9192fd 100644
--- a/drivers/hv/vmbus_drv.c
+++ b/drivers/hv/vmbus_drv.c
@@ -753,10 +753,35 @@ 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())
+		return -ENODEV;
+
 	init_completion(&probe_event);
 
 	/*
-- 
1.7.1

RE: [PATCH] hv: fail the probing immediately when we are not in hyperv platform

[KY Srinivasan]

> -----Original Message-----
> From: Jason Wang [mailto:jasowang@redhat.com]
> Sent: Friday, August 17, 2012 6:53 AM
> To: devel@linuxdriverproject.org; linux-kernel@vger.kernel.org
> Cc: Jason Wang; KY Srinivasan; Haiyang Zhang
> Subject: [PATCH] hv: fail the probing immediately when we are not in hyperv
> platform
> 
> We wait for about 5 seconds for the success of the hyperv registration even if
> we were not in hyperv platform. This is suboptimal, so the patch check the cpuid
> in the beginning of hv_acpi_init() instead of in vmbus_bus_init() to fail the
> probing immediately.
> 
> Cc: "K. Y. Srinivasan" <kys@microsoft.com>
> Cc: Haiyang Zhang <haiyangz@microsoft.com>
> Signed-off-by: Jason Wang <jasowang@redhat.com>
> ---
>  drivers/hv/hv.c        |   25 -------------------------
>  drivers/hv/vmbus_drv.c |   25 +++++++++++++++++++++++++
>  2 files changed, 25 insertions(+), 25 deletions(-)
> 
> diff --git a/drivers/hv/hv.c b/drivers/hv/hv.c
> index 86f8885..a18ee5d 100644
> --- a/drivers/hv/hv.c
> +++ b/drivers/hv/hv.c
> @@ -38,28 +38,6 @@ struct hv_context hv_context = {
>  };
> 
>  /*
> - * 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;
> -}
> -
> -/*
>   * query_hypervisor_info - Get version info of the windows hypervisor
>   */
>  static int query_hypervisor_info(void)
> @@ -159,9 +137,6 @@ int hv_init(void)
>  	memset(hv_context.synic_message_page, 0,
>  	       sizeof(void *) * NR_CPUS);
> 
> -	if (!query_hypervisor_presence())
> -		goto cleanup;
> -
>  	max_leaf = query_hypervisor_info();
> 
>  	/* Write our OS info */
> diff --git a/drivers/hv/vmbus_drv.c b/drivers/hv/vmbus_drv.c
> index 4748086..a9192fd 100644
> --- a/drivers/hv/vmbus_drv.c
> +++ b/drivers/hv/vmbus_drv.c
> @@ -753,10 +753,35 @@ 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())
> +		return -ENODEV;
> +
>  	init_completion(&probe_event);
> 
>  	/*
> --
> 1.7.1

Thank you.

Acked-by:  K. Y. Srinivasan <kys@microsoft.com>