diff mbox series

[v2] watchdog: iTCO_wdt: Account for rebooting on second timeout

Message ID 0b8bb307-d08b-41b5-696c-305cdac6789c@siemens.com (mailing list archive)
State Accepted
Headers show
Series [v2] watchdog: iTCO_wdt: Account for rebooting on second timeout | expand

Commit Message

Jan Kiszka May 30, 2021, 11:24 a.m. UTC 
From: Jan Kiszka <jan.kiszka@siemens.com>

This was already attempted to fix via 1fccb73011ea: If the BIOS did not
enable TCO SMIs, the timer definitely needs to trigger twice in order to
cause a reboot. If TCO SMIs are on, as well as SMIs in general, we can
continue to assume that the BIOS will perform a reboot on the first
timeout.

QEMU with its ICH9 and related BIOS falls into the former category,
currently taking twice the configured timeout in order to reboot the
machine. For iTCO version that fall under turn_SMI_watchdog_clear_off,
this is also true and was currently only addressed for v1, irrespective
of the turn_SMI_watchdog_clear_off value.

Signed-off-by: Jan Kiszka <jan.kiszka@siemens.com>
---

Changes in v2:
 - consider GBL_SMI_EN as well

 drivers/watchdog/iTCO_wdt.c | 12 +++++++++---
 1 file changed, 9 insertions(+), 3 deletions(-)

Comments

Guenter Roeck May 30, 2021, 1:19 p.m. UTC | #1 
On Sun, May 30, 2021 at 01:24:23PM +0200, Jan Kiszka wrote:
> From: Jan Kiszka <jan.kiszka@siemens.com>
> 
> This was already attempted to fix via 1fccb73011ea: If the BIOS did not
> enable TCO SMIs, the timer definitely needs to trigger twice in order to
> cause a reboot. If TCO SMIs are on, as well as SMIs in general, we can
> continue to assume that the BIOS will perform a reboot on the first
> timeout.
> 
> QEMU with its ICH9 and related BIOS falls into the former category,
> currently taking twice the configured timeout in order to reboot the
> machine. For iTCO version that fall under turn_SMI_watchdog_clear_off,
> this is also true and was currently only addressed for v1, irrespective
> of the turn_SMI_watchdog_clear_off value.
> 
> Signed-off-by: Jan Kiszka <jan.kiszka@siemens.com>
> ---
> 
> Changes in v2:
>  - consider GBL_SMI_EN as well
> 
>  drivers/watchdog/iTCO_wdt.c | 12 +++++++++---
>  1 file changed, 9 insertions(+), 3 deletions(-)
> 
> diff --git a/drivers/watchdog/iTCO_wdt.c b/drivers/watchdog/iTCO_wdt.c
> index bf31d7b67a69..3f1324871cfd 100644
> --- a/drivers/watchdog/iTCO_wdt.c
> +++ b/drivers/watchdog/iTCO_wdt.c
> @@ -71,6 +71,8 @@
>  #define TCOBASE(p)	((p)->tco_res->start)
>  /* SMI Control and Enable Register */
>  #define SMI_EN(p)	((p)->smi_res->start)
> +#define TCO_EN		(1 << 13)
> +#define GBL_SMI_EN	(1 << 0)
>  
>  #define TCO_RLD(p)	(TCOBASE(p) + 0x00) /* TCO Timer Reload/Curr. Value */
>  #define TCOv1_TMR(p)	(TCOBASE(p) + 0x01) /* TCOv1 Timer Initial Value*/
> @@ -355,8 +357,12 @@ static int iTCO_wdt_set_timeout(struct watchdog_device *wd_dev, unsigned int t)
>  
>  	tmrval = seconds_to_ticks(p, t);
>  
> -	/* For TCO v1 the timer counts down twice before rebooting */
> -	if (p->iTCO_version == 1)
> +	/*
> +	 * If TCO SMIs are off, the timer counts down twice before rebooting.
> +	 * Otherwise, the BIOS generally reboots when the SMI triggers.
> +	 */
> +	if (p->smi_res &&
> +	    (SMI_EN(p) & (TCO_EN | GBL_SMI_EN)) != (TCO_EN | GBL_SMI_EN))
>  		tmrval /= 2;

This expands the scope of this adjustment to all versions, while at the same
time making it conditional for v1. Is this correct ? What for systems with v1
TCO where the above conditions are not met ?

Guenter

>  
>  	/* from the specs: */
> @@ -521,7 +527,7 @@ static int iTCO_wdt_probe(struct platform_device *pdev)
>  		 * Disables TCO logic generating an SMI#
>  		 */
>  		val32 = inl(SMI_EN(p));
> -		val32 &= 0xffffdfff;	/* Turn off SMI clearing watchdog */
> +		val32 &= ~TCO_EN;	/* Turn off SMI clearing watchdog */
>  		outl(val32, SMI_EN(p));
>  	}
>  
> -- 
> 2.26.2
Jan Kiszka May 31, 2021, 8:27 a.m. UTC | #2 
On 30.05.21 15:19, Guenter Roeck wrote:
> On Sun, May 30, 2021 at 01:24:23PM +0200, Jan Kiszka wrote:
>> From: Jan Kiszka <jan.kiszka@siemens.com>
>>
>> This was already attempted to fix via 1fccb73011ea: If the BIOS did not
>> enable TCO SMIs, the timer definitely needs to trigger twice in order to
>> cause a reboot. If TCO SMIs are on, as well as SMIs in general, we can
>> continue to assume that the BIOS will perform a reboot on the first
>> timeout.
>>
>> QEMU with its ICH9 and related BIOS falls into the former category,
>> currently taking twice the configured timeout in order to reboot the
>> machine. For iTCO version that fall under turn_SMI_watchdog_clear_off,
>> this is also true and was currently only addressed for v1, irrespective
>> of the turn_SMI_watchdog_clear_off value.
>>
>> Signed-off-by: Jan Kiszka <jan.kiszka@siemens.com>
>> ---
>>
>> Changes in v2:
>>  - consider GBL_SMI_EN as well
>>
>>  drivers/watchdog/iTCO_wdt.c | 12 +++++++++---
>>  1 file changed, 9 insertions(+), 3 deletions(-)
>>
>> diff --git a/drivers/watchdog/iTCO_wdt.c b/drivers/watchdog/iTCO_wdt.c
>> index bf31d7b67a69..3f1324871cfd 100644
>> --- a/drivers/watchdog/iTCO_wdt.c
>> +++ b/drivers/watchdog/iTCO_wdt.c
>> @@ -71,6 +71,8 @@
>>  #define TCOBASE(p)	((p)->tco_res->start)
>>  /* SMI Control and Enable Register */
>>  #define SMI_EN(p)	((p)->smi_res->start)
>> +#define TCO_EN		(1 << 13)
>> +#define GBL_SMI_EN	(1 << 0)
>>  
>>  #define TCO_RLD(p)	(TCOBASE(p) + 0x00) /* TCO Timer Reload/Curr. Value */
>>  #define TCOv1_TMR(p)	(TCOBASE(p) + 0x01) /* TCOv1 Timer Initial Value*/
>> @@ -355,8 +357,12 @@ static int iTCO_wdt_set_timeout(struct watchdog_device *wd_dev, unsigned int t)
>>  
>>  	tmrval = seconds_to_ticks(p, t);
>>  
>> -	/* For TCO v1 the timer counts down twice before rebooting */
>> -	if (p->iTCO_version == 1)
>> +	/*
>> +	 * If TCO SMIs are off, the timer counts down twice before rebooting.
>> +	 * Otherwise, the BIOS generally reboots when the SMI triggers.
>> +	 */
>> +	if (p->smi_res &&
>> +	    (SMI_EN(p) & (TCO_EN | GBL_SMI_EN)) != (TCO_EN | GBL_SMI_EN))
>>  		tmrval /= 2;
> 
> This expands the scope of this adjustment to all versions, while at the same
> time making it conditional for v1. Is this correct ? What for systems with v1
> TCO where the above conditions are not met ?

Yes, this is intended. You find the reference to "reboots on second
timeout" even in latest EHL datasheets (v6).

Jan

> 
> Guenter
> 
>>  
>>  	/* from the specs: */
>> @@ -521,7 +527,7 @@ static int iTCO_wdt_probe(struct platform_device *pdev)
>>  		 * Disables TCO logic generating an SMI#
>>  		 */
>>  		val32 = inl(SMI_EN(p));
>> -		val32 &= 0xffffdfff;	/* Turn off SMI clearing watchdog */
>> +		val32 &= ~TCO_EN;	/* Turn off SMI clearing watchdog */
>>  		outl(val32, SMI_EN(p));
>>  	}
>>  
>> -- 
>> 2.26.2
Jan Kiszka May 31, 2021, 9:18 a.m. UTC | #3 
On 31.05.21 10:27, Jan Kiszka wrote:
> On 30.05.21 15:19, Guenter Roeck wrote:
>> On Sun, May 30, 2021 at 01:24:23PM +0200, Jan Kiszka wrote:
>>> From: Jan Kiszka <jan.kiszka@siemens.com>
>>>
>>> This was already attempted to fix via 1fccb73011ea: If the BIOS did not
>>> enable TCO SMIs, the timer definitely needs to trigger twice in order to
>>> cause a reboot. If TCO SMIs are on, as well as SMIs in general, we can
>>> continue to assume that the BIOS will perform a reboot on the first
>>> timeout.
>>>
>>> QEMU with its ICH9 and related BIOS falls into the former category,
>>> currently taking twice the configured timeout in order to reboot the
>>> machine. For iTCO version that fall under turn_SMI_watchdog_clear_off,
>>> this is also true and was currently only addressed for v1, irrespective
>>> of the turn_SMI_watchdog_clear_off value.
>>>
>>> Signed-off-by: Jan Kiszka <jan.kiszka@siemens.com>
>>> ---
>>>
>>> Changes in v2:
>>>  - consider GBL_SMI_EN as well
>>>
>>>  drivers/watchdog/iTCO_wdt.c | 12 +++++++++---
>>>  1 file changed, 9 insertions(+), 3 deletions(-)
>>>
>>> diff --git a/drivers/watchdog/iTCO_wdt.c b/drivers/watchdog/iTCO_wdt.c
>>> index bf31d7b67a69..3f1324871cfd 100644
>>> --- a/drivers/watchdog/iTCO_wdt.c
>>> +++ b/drivers/watchdog/iTCO_wdt.c
>>> @@ -71,6 +71,8 @@
>>>  #define TCOBASE(p)	((p)->tco_res->start)
>>>  /* SMI Control and Enable Register */
>>>  #define SMI_EN(p)	((p)->smi_res->start)
>>> +#define TCO_EN		(1 << 13)
>>> +#define GBL_SMI_EN	(1 << 0)
>>>  
>>>  #define TCO_RLD(p)	(TCOBASE(p) + 0x00) /* TCO Timer Reload/Curr. Value */
>>>  #define TCOv1_TMR(p)	(TCOBASE(p) + 0x01) /* TCOv1 Timer Initial Value*/
>>> @@ -355,8 +357,12 @@ static int iTCO_wdt_set_timeout(struct watchdog_device *wd_dev, unsigned int t)
>>>  
>>>  	tmrval = seconds_to_ticks(p, t);
>>>  
>>> -	/* For TCO v1 the timer counts down twice before rebooting */
>>> -	if (p->iTCO_version == 1)
>>> +	/*
>>> +	 * If TCO SMIs are off, the timer counts down twice before rebooting.
>>> +	 * Otherwise, the BIOS generally reboots when the SMI triggers.
>>> +	 */
>>> +	if (p->smi_res &&
>>> +	    (SMI_EN(p) & (TCO_EN | GBL_SMI_EN)) != (TCO_EN | GBL_SMI_EN))
>>>  		tmrval /= 2;
>>
>> This expands the scope of this adjustment to all versions, while at the same
>> time making it conditional for v1. Is this correct ? What for systems with v1
>> TCO where the above conditions are not met ?
> 
> Yes, this is intended. You find the reference to "reboots on second
> timeout" even in latest EHL datasheets (v6).
> 

To make it clearer: By default, we disabled SMIs on v1, thus had to
adjust the timeout there unconditionally. In QEMU (v2), the firmware
does not enable SMI, and we failed to handle that. Conceptually, any
platform on any (known) version that does not use TCO SMIs is affected.

Jan
Guenter Roeck June 2, 2021, 11:24 a.m. UTC | #4 
On Sun, May 30, 2021 at 01:24:23PM +0200, Jan Kiszka wrote:
> From: Jan Kiszka <jan.kiszka@siemens.com>
> 
> This was already attempted to fix via 1fccb73011ea: If the BIOS did not
> enable TCO SMIs, the timer definitely needs to trigger twice in order to
> cause a reboot. If TCO SMIs are on, as well as SMIs in general, we can
> continue to assume that the BIOS will perform a reboot on the first
> timeout.
> 
> QEMU with its ICH9 and related BIOS falls into the former category,
> currently taking twice the configured timeout in order to reboot the
> machine. For iTCO version that fall under turn_SMI_watchdog_clear_off,
> this is also true and was currently only addressed for v1, irrespective
> of the turn_SMI_watchdog_clear_off value.
> 
> Signed-off-by: Jan Kiszka <jan.kiszka@siemens.com>

Reviewed-by: Guenter Roeck <linux@roeck-us.net>

> ---
> 
> Changes in v2:
>  - consider GBL_SMI_EN as well
> 
>  drivers/watchdog/iTCO_wdt.c | 12 +++++++++---
>  1 file changed, 9 insertions(+), 3 deletions(-)
> 
> diff --git a/drivers/watchdog/iTCO_wdt.c b/drivers/watchdog/iTCO_wdt.c
> index bf31d7b67a69..3f1324871cfd 100644
> --- a/drivers/watchdog/iTCO_wdt.c
> +++ b/drivers/watchdog/iTCO_wdt.c
> @@ -71,6 +71,8 @@
>  #define TCOBASE(p)	((p)->tco_res->start)
>  /* SMI Control and Enable Register */
>  #define SMI_EN(p)	((p)->smi_res->start)
> +#define TCO_EN		(1 << 13)
> +#define GBL_SMI_EN	(1 << 0)
>  
>  #define TCO_RLD(p)	(TCOBASE(p) + 0x00) /* TCO Timer Reload/Curr. Value */
>  #define TCOv1_TMR(p)	(TCOBASE(p) + 0x01) /* TCOv1 Timer Initial Value*/
> @@ -355,8 +357,12 @@ static int iTCO_wdt_set_timeout(struct watchdog_device *wd_dev, unsigned int t)
>  
>  	tmrval = seconds_to_ticks(p, t);
>  
> -	/* For TCO v1 the timer counts down twice before rebooting */
> -	if (p->iTCO_version == 1)
> +	/*
> +	 * If TCO SMIs are off, the timer counts down twice before rebooting.
> +	 * Otherwise, the BIOS generally reboots when the SMI triggers.
> +	 */
> +	if (p->smi_res &&
> +	    (SMI_EN(p) & (TCO_EN | GBL_SMI_EN)) != (TCO_EN | GBL_SMI_EN))
>  		tmrval /= 2;
>  
>  	/* from the specs: */
> @@ -521,7 +527,7 @@ static int iTCO_wdt_probe(struct platform_device *pdev)
>  		 * Disables TCO logic generating an SMI#
>  		 */
>  		val32 = inl(SMI_EN(p));
> -		val32 &= 0xffffdfff;	/* Turn off SMI clearing watchdog */
> +		val32 &= ~TCO_EN;	/* Turn off SMI clearing watchdog */
>  		outl(val32, SMI_EN(p));
>  	}
>  
> -- 
> 2.26.2
diff mbox series

Patch

diff --git a/drivers/watchdog/iTCO_wdt.c b/drivers/watchdog/iTCO_wdt.c
index bf31d7b67a69..3f1324871cfd 100644
--- a/drivers/watchdog/iTCO_wdt.c
+++ b/drivers/watchdog/iTCO_wdt.c
@@ -71,6 +71,8 @@ 
 #define TCOBASE(p)	((p)->tco_res->start)
 /* SMI Control and Enable Register */
 #define SMI_EN(p)	((p)->smi_res->start)
+#define TCO_EN		(1 << 13)
+#define GBL_SMI_EN	(1 << 0)
 
 #define TCO_RLD(p)	(TCOBASE(p) + 0x00) /* TCO Timer Reload/Curr. Value */
 #define TCOv1_TMR(p)	(TCOBASE(p) + 0x01) /* TCOv1 Timer Initial Value*/
@@ -355,8 +357,12 @@  static int iTCO_wdt_set_timeout(struct watchdog_device *wd_dev, unsigned int t)
 
 	tmrval = seconds_to_ticks(p, t);
 
-	/* For TCO v1 the timer counts down twice before rebooting */
-	if (p->iTCO_version == 1)
+	/*
+	 * If TCO SMIs are off, the timer counts down twice before rebooting.
+	 * Otherwise, the BIOS generally reboots when the SMI triggers.
+	 */
+	if (p->smi_res &&
+	    (SMI_EN(p) & (TCO_EN | GBL_SMI_EN)) != (TCO_EN | GBL_SMI_EN))
 		tmrval /= 2;
 
 	/* from the specs: */
@@ -521,7 +527,7 @@  static int iTCO_wdt_probe(struct platform_device *pdev)
 		 * Disables TCO logic generating an SMI#
 		 */
 		val32 = inl(SMI_EN(p));
-		val32 &= 0xffffdfff;	/* Turn off SMI clearing watchdog */
+		val32 &= ~TCO_EN;	/* Turn off SMI clearing watchdog */
 		outl(val32, SMI_EN(p));
 	}