Re: [PATCH 4/7] clocksource: arch_timer: Add support for not-fw-configured timer on ARM64

[Daniel Lezcano]

On 15/10/2018 14:12, Marek Szyprowski wrote:
> Hi All,
> 
> On 2018-10-08 15:17, Marc Zyngier wrote:
>> + Mark Rutland
>>
>> Hi Marek,
>>
>> On 08/10/18 13:50, Marek Szyprowski wrote:
>>> Use common infrastructure for ARM Architected Timers erratum to enable
>>> support for systems with broken CPU firmware (timer registers not
>>> properly configured). This mode has been already availabled on ARM
>>> (32bits) architecture. This enables to run Linux kernel on ARM64 boards
>>> using physical architected timers instead of the virtual ones. Examples
>>> of such system with broken firmware are Samsung Exynos5433 SoC based
>>> TM2(e) boards, which is already deployed for years and updating firmware
>>> is not possible.
>>>
>>> Signed-off-by: Marek Szyprowski 
>>> ---
>>>   drivers/clocksource/Kconfig  | 11 +++
>>>   drivers/clocksource/arm_arch_timer.c | 15 ---
>>>   2 files changed, 23 insertions(+), 3 deletions(-)
>>>
>>> diff --git a/drivers/clocksource/Kconfig b/drivers/clocksource/Kconfig
>>> index a11f4ba98b05..a30752579b03 100644
>>> --- a/drivers/clocksource/Kconfig
>>> +++ b/drivers/clocksource/Kconfig
>>> @@ -364,6 +364,17 @@ config ARM64_ERRATUM_858921
>>>     The workaround will be dynamically enabled when an affected
>>>     core is detected.
>>>   +config ARCH_TIMER_REGISTERS_NOT_FW_CONFIGURED
>>> +    bool "Workaround for arch timer registers not configured by
>>> firmware"
>>> +    default y
>>> +    select ARM_ARCH_TIMER_OOL_WORKAROUND
>>> +    depends on ARM_ARCH_TIMER && ARM64
>>> +    help
>>> +  This option enables a workaround for boards, on which arch timer
>>> +  registers are not properly configured by the board firmware.
>>> +  The workaround will be dynamically enabled when an affected
>>> +  board is detected.
>>> +
>>
>> I'm sorry, but I'm strongly pushing back on this.
>>
>> This horrible hack was accepted with the express condition that it
>> would be limited to ARMv7 platforms (on the ground that we never
>> really documented the arch timer boot requirements on that version of
>> the architecture), and would never proliferate on arm64. From day 1,
>> we established what the boot protocol was, and we mandated that either:
>>
>> - kernel is entered at EL2 on all CPUs
>> - cntvoff_el2 is zeroed on all CPUs
>>
>> and we've got most people to fix their firmware, or live with the
>> consequences. If these machines cannot receive a non-broken firmware,
>> what are the odds that they will receive a mainline kernel?
> 
> Well, I know that the firmware is broken, but I cannot do anything about it.
> On the other hand updating kernel is still possible and mainline runs fine
> on TM2(e) boards. I will send v2 without this patch then.

I second Marc's opinion.



-- 
  Linaro.org │ Open source software for ARM SoCs

Follow Linaro:   Facebook |
 Twitter |
 Blog

Re: [PATCH 4/7] clocksource: arch_timer: Add support for not-fw-configured timer on ARM64

[Daniel Lezcano]

On 15/10/2018 14:12, Marek Szyprowski wrote:
> Hi All,
> 
> On 2018-10-08 15:17, Marc Zyngier wrote:
>> + Mark Rutland
>>
>> Hi Marek,
>>
>> On 08/10/18 13:50, Marek Szyprowski wrote:
>>> Use common infrastructure for ARM Architected Timers erratum to enable
>>> support for systems with broken CPU firmware (timer registers not
>>> properly configured). This mode has been already availabled on ARM
>>> (32bits) architecture. This enables to run Linux kernel on ARM64 boards
>>> using physical architected timers instead of the virtual ones. Examples
>>> of such system with broken firmware are Samsung Exynos5433 SoC based
>>> TM2(e) boards, which is already deployed for years and updating firmware
>>> is not possible.
>>>
>>> Signed-off-by: Marek Szyprowski 
>>> ---
>>>   drivers/clocksource/Kconfig  | 11 +++
>>>   drivers/clocksource/arm_arch_timer.c | 15 ---
>>>   2 files changed, 23 insertions(+), 3 deletions(-)
>>>
>>> diff --git a/drivers/clocksource/Kconfig b/drivers/clocksource/Kconfig
>>> index a11f4ba98b05..a30752579b03 100644
>>> --- a/drivers/clocksource/Kconfig
>>> +++ b/drivers/clocksource/Kconfig
>>> @@ -364,6 +364,17 @@ config ARM64_ERRATUM_858921
>>>     The workaround will be dynamically enabled when an affected
>>>     core is detected.
>>>   +config ARCH_TIMER_REGISTERS_NOT_FW_CONFIGURED
>>> +    bool "Workaround for arch timer registers not configured by
>>> firmware"
>>> +    default y
>>> +    select ARM_ARCH_TIMER_OOL_WORKAROUND
>>> +    depends on ARM_ARCH_TIMER && ARM64
>>> +    help
>>> +  This option enables a workaround for boards, on which arch timer
>>> +  registers are not properly configured by the board firmware.
>>> +  The workaround will be dynamically enabled when an affected
>>> +  board is detected.
>>> +
>>
>> I'm sorry, but I'm strongly pushing back on this.
>>
>> This horrible hack was accepted with the express condition that it
>> would be limited to ARMv7 platforms (on the ground that we never
>> really documented the arch timer boot requirements on that version of
>> the architecture), and would never proliferate on arm64. From day 1,
>> we established what the boot protocol was, and we mandated that either:
>>
>> - kernel is entered at EL2 on all CPUs
>> - cntvoff_el2 is zeroed on all CPUs
>>
>> and we've got most people to fix their firmware, or live with the
>> consequences. If these machines cannot receive a non-broken firmware,
>> what are the odds that they will receive a mainline kernel?
> 
> Well, I know that the firmware is broken, but I cannot do anything about it.
> On the other hand updating kernel is still possible and mainline runs fine
> on TM2(e) boards. I will send v2 without this patch then.

I second Marc's opinion.



-- 
  Linaro.org │ Open source software for ARM SoCs

Follow Linaro:   Facebook |
 Twitter |
 Blog

Re: [PATCH 4/7] clocksource: arch_timer: Add support for not-fw-configured timer on ARM64

[Marek Szyprowski]

Hi All,

On 2018-10-08 15:17, Marc Zyngier wrote:
> + Mark Rutland
>
> Hi Marek,
>
> On 08/10/18 13:50, Marek Szyprowski wrote:
>> Use common infrastructure for ARM Architected Timers erratum to enable
>> support for systems with broken CPU firmware (timer registers not
>> properly configured). This mode has been already availabled on ARM
>> (32bits) architecture. This enables to run Linux kernel on ARM64 boards
>> using physical architected timers instead of the virtual ones. Examples
>> of such system with broken firmware are Samsung Exynos5433 SoC based
>> TM2(e) boards, which is already deployed for years and updating firmware
>> is not possible.
>>
>> Signed-off-by: Marek Szyprowski 
>> ---
>>   drivers/clocksource/Kconfig  | 11 +++
>>   drivers/clocksource/arm_arch_timer.c | 15 ---
>>   2 files changed, 23 insertions(+), 3 deletions(-)
>>
>> diff --git a/drivers/clocksource/Kconfig b/drivers/clocksource/Kconfig
>> index a11f4ba98b05..a30752579b03 100644
>> --- a/drivers/clocksource/Kconfig
>> +++ b/drivers/clocksource/Kconfig
>> @@ -364,6 +364,17 @@ config ARM64_ERRATUM_858921
>>     The workaround will be dynamically enabled when an affected
>>     core is detected.
>>   +config ARCH_TIMER_REGISTERS_NOT_FW_CONFIGURED
>> +    bool "Workaround for arch timer registers not configured by
>> firmware"
>> +    default y
>> +    select ARM_ARCH_TIMER_OOL_WORKAROUND
>> +    depends on ARM_ARCH_TIMER && ARM64
>> +    help
>> +  This option enables a workaround for boards, on which arch timer
>> +  registers are not properly configured by the board firmware.
>> +  The workaround will be dynamically enabled when an affected
>> +  board is detected.
>> +
>
> I'm sorry, but I'm strongly pushing back on this.
>
> This horrible hack was accepted with the express condition that it
> would be limited to ARMv7 platforms (on the ground that we never
> really documented the arch timer boot requirements on that version of
> the architecture), and would never proliferate on arm64. From day 1,
> we established what the boot protocol was, and we mandated that either:
>
> - kernel is entered at EL2 on all CPUs
> - cntvoff_el2 is zeroed on all CPUs
>
> and we've got most people to fix their firmware, or live with the
> consequences. If these machines cannot receive a non-broken firmware,
> what are the odds that they will receive a mainline kernel?

Well, I know that the firmware is broken, but I cannot do anything about it.
On the other hand updating kernel is still possible and mainline runs fine
on TM2(e) boards. I will send v2 without this patch then.

Best regards
-- 
Marek Szyprowski, PhD
Samsung R Institute Poland

Re: [PATCH 4/7] clocksource: arch_timer: Add support for not-fw-configured timer on ARM64

[Marek Szyprowski]

Hi All,

On 2018-10-08 15:17, Marc Zyngier wrote:
> + Mark Rutland
>
> Hi Marek,
>
> On 08/10/18 13:50, Marek Szyprowski wrote:
>> Use common infrastructure for ARM Architected Timers erratum to enable
>> support for systems with broken CPU firmware (timer registers not
>> properly configured). This mode has been already availabled on ARM
>> (32bits) architecture. This enables to run Linux kernel on ARM64 boards
>> using physical architected timers instead of the virtual ones. Examples
>> of such system with broken firmware are Samsung Exynos5433 SoC based
>> TM2(e) boards, which is already deployed for years and updating firmware
>> is not possible.
>>
>> Signed-off-by: Marek Szyprowski 
>> ---
>>   drivers/clocksource/Kconfig  | 11 +++
>>   drivers/clocksource/arm_arch_timer.c | 15 ---
>>   2 files changed, 23 insertions(+), 3 deletions(-)
>>
>> diff --git a/drivers/clocksource/Kconfig b/drivers/clocksource/Kconfig
>> index a11f4ba98b05..a30752579b03 100644
>> --- a/drivers/clocksource/Kconfig
>> +++ b/drivers/clocksource/Kconfig
>> @@ -364,6 +364,17 @@ config ARM64_ERRATUM_858921
>>     The workaround will be dynamically enabled when an affected
>>     core is detected.
>>   +config ARCH_TIMER_REGISTERS_NOT_FW_CONFIGURED
>> +    bool "Workaround for arch timer registers not configured by
>> firmware"
>> +    default y
>> +    select ARM_ARCH_TIMER_OOL_WORKAROUND
>> +    depends on ARM_ARCH_TIMER && ARM64
>> +    help
>> +  This option enables a workaround for boards, on which arch timer
>> +  registers are not properly configured by the board firmware.
>> +  The workaround will be dynamically enabled when an affected
>> +  board is detected.
>> +
>
> I'm sorry, but I'm strongly pushing back on this.
>
> This horrible hack was accepted with the express condition that it
> would be limited to ARMv7 platforms (on the ground that we never
> really documented the arch timer boot requirements on that version of
> the architecture), and would never proliferate on arm64. From day 1,
> we established what the boot protocol was, and we mandated that either:
>
> - kernel is entered at EL2 on all CPUs
> - cntvoff_el2 is zeroed on all CPUs
>
> and we've got most people to fix their firmware, or live with the
> consequences. If these machines cannot receive a non-broken firmware,
> what are the odds that they will receive a mainline kernel?

Well, I know that the firmware is broken, but I cannot do anything about it.
On the other hand updating kernel is still possible and mainline runs fine
on TM2(e) boards. I will send v2 without this patch then.

Best regards
-- 
Marek Szyprowski, PhD
Samsung R Institute Poland

Re: [PATCH 4/7] clocksource: arch_timer: Add support for not-fw-configured timer on ARM64

[Marc Zyngier]

+ Mark Rutland

Hi Marek,

On 08/10/18 13:50, Marek Szyprowski wrote:

Use common infrastructure for ARM Architected Timers erratum to enable
support for systems with broken CPU firmware (timer registers not
properly configured). This mode has been already availabled on ARM
(32bits) architecture. This enables to run Linux kernel on ARM64 boards
using physical architected timers instead of the virtual ones. Examples
of such system with broken firmware are Samsung Exynos5433 SoC based
TM2(e) boards, which is already deployed for years and updating firmware
is not possible.

Signed-off-by: Marek Szyprowski 
---
  drivers/clocksource/Kconfig  | 11 +++
  drivers/clocksource/arm_arch_timer.c | 15 ---
  2 files changed, 23 insertions(+), 3 deletions(-)

diff --git a/drivers/clocksource/Kconfig b/drivers/clocksource/Kconfig
index a11f4ba98b05..a30752579b03 100644
--- a/drivers/clocksource/Kconfig
+++ b/drivers/clocksource/Kconfig
@@ -364,6 +364,17 @@ config ARM64_ERRATUM_858921
  The workaround will be dynamically enabled when an affected
  core is detected.
  
+config ARCH_TIMER_REGISTERS_NOT_FW_CONFIGURED

+   bool "Workaround for arch timer registers not configured by firmware"
+   default y
+   select ARM_ARCH_TIMER_OOL_WORKAROUND
+   depends on ARM_ARCH_TIMER && ARM64
+   help
+ This option enables a workaround for boards, on which arch timer
+ registers are not properly configured by the board firmware.
+ The workaround will be dynamically enabled when an affected
+ board is detected.
+


I'm sorry, but I'm strongly pushing back on this.

This horrible hack was accepted with the express condition that it would 
be limited to ARMv7 platforms (on the ground that we never really 
documented the arch timer boot requirements on that version of the 
architecture), and would never proliferate on arm64. From day 1, we 
established what the boot protocol was, and we mandated that either:


- kernel is entered at EL2 on all CPUs
- cntvoff_el2 is zeroed on all CPUs

and we've got most people to fix their firmware, or live with the 
consequences. If these machines cannot receive a non-broken firmware, 
what are the odds that they will receive a mainline kernel?


Thanks,

M.
--
Jazz is not dead. It just smells funny...

Re: [PATCH 4/7] clocksource: arch_timer: Add support for not-fw-configured timer on ARM64

[Marc Zyngier]

+ Mark Rutland

Hi Marek,

On 08/10/18 13:50, Marek Szyprowski wrote:

Use common infrastructure for ARM Architected Timers erratum to enable
support for systems with broken CPU firmware (timer registers not
properly configured). This mode has been already availabled on ARM
(32bits) architecture. This enables to run Linux kernel on ARM64 boards
using physical architected timers instead of the virtual ones. Examples
of such system with broken firmware are Samsung Exynos5433 SoC based
TM2(e) boards, which is already deployed for years and updating firmware
is not possible.

Signed-off-by: Marek Szyprowski 
---
  drivers/clocksource/Kconfig  | 11 +++
  drivers/clocksource/arm_arch_timer.c | 15 ---
  2 files changed, 23 insertions(+), 3 deletions(-)

diff --git a/drivers/clocksource/Kconfig b/drivers/clocksource/Kconfig
index a11f4ba98b05..a30752579b03 100644
--- a/drivers/clocksource/Kconfig
+++ b/drivers/clocksource/Kconfig
@@ -364,6 +364,17 @@ config ARM64_ERRATUM_858921
  The workaround will be dynamically enabled when an affected
  core is detected.
  
+config ARCH_TIMER_REGISTERS_NOT_FW_CONFIGURED

+   bool "Workaround for arch timer registers not configured by firmware"
+   default y
+   select ARM_ARCH_TIMER_OOL_WORKAROUND
+   depends on ARM_ARCH_TIMER && ARM64
+   help
+ This option enables a workaround for boards, on which arch timer
+ registers are not properly configured by the board firmware.
+ The workaround will be dynamically enabled when an affected
+ board is detected.
+


I'm sorry, but I'm strongly pushing back on this.

This horrible hack was accepted with the express condition that it would 
be limited to ARMv7 platforms (on the ground that we never really 
documented the arch timer boot requirements on that version of the 
architecture), and would never proliferate on arm64. From day 1, we 
established what the boot protocol was, and we mandated that either:


- kernel is entered at EL2 on all CPUs
- cntvoff_el2 is zeroed on all CPUs

and we've got most people to fix their firmware, or live with the 
consequences. If these machines cannot receive a non-broken firmware, 
what are the odds that they will receive a mainline kernel?


Thanks,

M.
--
Jazz is not dead. It just smells funny...

[PATCH 4/7] clocksource: arch_timer: Add support for not-fw-configured timer on ARM64

[Marek Szyprowski]

Use common infrastructure for ARM Architected Timers erratum to enable
support for systems with broken CPU firmware (timer registers not
properly configured). This mode has been already availabled on ARM
(32bits) architecture. This enables to run Linux kernel on ARM64 boards
using physical architected timers instead of the virtual ones. Examples
of such system with broken firmware are Samsung Exynos5433 SoC based
TM2(e) boards, which is already deployed for years and updating firmware
is not possible.

Signed-off-by: Marek Szyprowski 
---
 drivers/clocksource/Kconfig  | 11 +++
 drivers/clocksource/arm_arch_timer.c | 15 ---
 2 files changed, 23 insertions(+), 3 deletions(-)

diff --git a/drivers/clocksource/Kconfig b/drivers/clocksource/Kconfig
index a11f4ba98b05..a30752579b03 100644
--- a/drivers/clocksource/Kconfig
+++ b/drivers/clocksource/Kconfig
@@ -364,6 +364,17 @@ config ARM64_ERRATUM_858921
  The workaround will be dynamically enabled when an affected
  core is detected.
 
+config ARCH_TIMER_REGISTERS_NOT_FW_CONFIGURED
+   bool "Workaround for arch timer registers not configured by firmware"
+   default y
+   select ARM_ARCH_TIMER_OOL_WORKAROUND
+   depends on ARM_ARCH_TIMER && ARM64
+   help
+ This option enables a workaround for boards, on which arch timer
+ registers are not properly configured by the board firmware.
+ The workaround will be dynamically enabled when an affected
+ board is detected.
+
 config ARM_GLOBAL_TIMER
bool "Support for the ARM global timer" if COMPILE_TEST
select TIMER_OF if OF
diff --git a/drivers/clocksource/arm_arch_timer.c 
b/drivers/clocksource/arm_arch_timer.c
index 9a7d4dc00b6e..b6f109654daf 100644
--- a/drivers/clocksource/arm_arch_timer.c
+++ b/drivers/clocksource/arm_arch_timer.c
@@ -423,6 +423,14 @@ static const struct arch_timer_erratum_workaround 
ool_workarounds[] = {
.read_cntvct_el0 = arm64_1188873_read_cntvct_el0,
},
 #endif
+#ifdef CONFIG_ARCH_TIMER_REGISTERS_NOT_FW_CONFIGURED
+   {
+   .match_type = ate_match_dt,
+   .id = "arm,cpu-registers-not-fw-configured",
+   .desc = "broken CPU firmware (timer registers not configured)",
+   .read_cntvct_el0 = arch_counter_get_cntpct,
+   },
+#endif
 };
 
 typedef bool (*ate_match_fn_t)(const struct arch_timer_erratum_workaround *,
@@ -1234,9 +1242,10 @@ static int __init arch_timer_of_init(struct device_node 
*np)
 * If we cannot rely on firmware initializing the timer registers then
 * we should use the physical timers instead.
 */
-   if (IS_ENABLED(CONFIG_ARM) &&
-   of_property_read_bool(np, "arm,cpu-registers-not-fw-configured"))
-   arch_timer_uses_ppi = ARCH_TIMER_PHYS_SECURE_PPI;
+   if (of_property_read_bool(np, "arm,cpu-registers-not-fw-configured"))
+   arch_timer_uses_ppi = IS_ENABLED(CONFIG_ARM64) ?
+   ARCH_TIMER_PHYS_NONSECURE_PPI :
+   ARCH_TIMER_PHYS_SECURE_PPI;
else
arch_timer_uses_ppi = arch_timer_select_ppi();
 
-- 
2.17.1

[PATCH 4/7] clocksource: arch_timer: Add support for not-fw-configured timer on ARM64

[Marek Szyprowski]

Use common infrastructure for ARM Architected Timers erratum to enable
support for systems with broken CPU firmware (timer registers not
properly configured). This mode has been already availabled on ARM
(32bits) architecture. This enables to run Linux kernel on ARM64 boards
using physical architected timers instead of the virtual ones. Examples
of such system with broken firmware are Samsung Exynos5433 SoC based
TM2(e) boards, which is already deployed for years and updating firmware
is not possible.

Signed-off-by: Marek Szyprowski 
---
 drivers/clocksource/Kconfig  | 11 +++
 drivers/clocksource/arm_arch_timer.c | 15 ---
 2 files changed, 23 insertions(+), 3 deletions(-)

diff --git a/drivers/clocksource/Kconfig b/drivers/clocksource/Kconfig
index a11f4ba98b05..a30752579b03 100644
--- a/drivers/clocksource/Kconfig
+++ b/drivers/clocksource/Kconfig
@@ -364,6 +364,17 @@ config ARM64_ERRATUM_858921
  The workaround will be dynamically enabled when an affected
  core is detected.
 
+config ARCH_TIMER_REGISTERS_NOT_FW_CONFIGURED
+   bool "Workaround for arch timer registers not configured by firmware"
+   default y
+   select ARM_ARCH_TIMER_OOL_WORKAROUND
+   depends on ARM_ARCH_TIMER && ARM64
+   help
+ This option enables a workaround for boards, on which arch timer
+ registers are not properly configured by the board firmware.
+ The workaround will be dynamically enabled when an affected
+ board is detected.
+
 config ARM_GLOBAL_TIMER
bool "Support for the ARM global timer" if COMPILE_TEST
select TIMER_OF if OF
diff --git a/drivers/clocksource/arm_arch_timer.c 
b/drivers/clocksource/arm_arch_timer.c
index 9a7d4dc00b6e..b6f109654daf 100644
--- a/drivers/clocksource/arm_arch_timer.c
+++ b/drivers/clocksource/arm_arch_timer.c
@@ -423,6 +423,14 @@ static const struct arch_timer_erratum_workaround 
ool_workarounds[] = {
.read_cntvct_el0 = arm64_1188873_read_cntvct_el0,
},
 #endif
+#ifdef CONFIG_ARCH_TIMER_REGISTERS_NOT_FW_CONFIGURED
+   {
+   .match_type = ate_match_dt,
+   .id = "arm,cpu-registers-not-fw-configured",
+   .desc = "broken CPU firmware (timer registers not configured)",
+   .read_cntvct_el0 = arch_counter_get_cntpct,
+   },
+#endif
 };
 
 typedef bool (*ate_match_fn_t)(const struct arch_timer_erratum_workaround *,
@@ -1234,9 +1242,10 @@ static int __init arch_timer_of_init(struct device_node 
*np)
 * If we cannot rely on firmware initializing the timer registers then
 * we should use the physical timers instead.
 */
-   if (IS_ENABLED(CONFIG_ARM) &&
-   of_property_read_bool(np, "arm,cpu-registers-not-fw-configured"))
-   arch_timer_uses_ppi = ARCH_TIMER_PHYS_SECURE_PPI;
+   if (of_property_read_bool(np, "arm,cpu-registers-not-fw-configured"))
+   arch_timer_uses_ppi = IS_ENABLED(CONFIG_ARM64) ?
+   ARCH_TIMER_PHYS_NONSECURE_PPI :
+   ARCH_TIMER_PHYS_SECURE_PPI;
else
arch_timer_uses_ppi = arch_timer_select_ppi();
 
-- 
2.17.1