[PATCH] powerpc/entry: Use hard_irq_disable() in arch_interrupt_exit_prepare()

[PATCH] powerpc/entry: Use hard_irq_disable() in arch_interrupt_exit_prepare()

[Mukesh Kumar Chaurasiya (IBM)]

commit 334f3f6d7a16 ("powerpc/entry: Disable interrupts before irqentry_exit")
fixed a BUG in preempt_schedule_irq() by calling local_irq_disable()
unconditionally in arch_interrupt_exit_prepare() before irqentry_exit().
The fix is correct in intent but uses the wrong primitive for PPC64.

On PPC64, local_irq_disable() only sets the soft-mask
(irq_soft_mask = IRQS_DISABLED). It does not set PACA_IRQ_HARD_DIS in
irq_happened and does not clear MSR[EE].

This causes a continuous WARN_ON boot hang on Power11 pSeries LPARs
using the dedicated-cede cpuidle path. When the CPU wakes from H_CEDE,
interrupt_exit_kernel_prepare() calls replay_soft_interrupts(), which
dispatches pending async handlers (timer_interrupt, do_IRQ) using the
DEFINE_INTERRUPT_HANDLER_ASYNC macro. That macro calls
arch_interrupt_async_exit_prepare() -> arch_interrupt_exit_prepare()
before irqentry_exit(). With local_irq_disable(), PACA_IRQ_HARD_DIS
is not set, but next_interrupt() unconditionally asserts it:

  WARN_ON(!(local_paca->irq_happened & PACA_IRQ_HARD_DIS));

This fires on every replayed interrupt, looping indefinitely and
preventing boot completion.

Fix this by replacing local_irq_disable() with hard_irq_disable().
On PPC64, hard_irq_disable() sets irq_soft_mask to IRQS_ALL_DISABLED,
sets PACA_IRQ_HARD_DIS in irq_happened, and clears MSR[EE] — satisfying
all of:

  - lockdep_assert_irqs_disabled() in irqentry_exit_to_kernel_mode()
  - next_interrupt()'s WARN_ON(!(irq_happened & PACA_IRQ_HARD_DIS))
  - preempt_schedule_irq()'s BUG_ON(!irqs_disabled())

On PPC32/non-64, hard_irq_disable() is equivalent to local_irq_disable(),
so there is no regression on those platforms.

Fixes: 334f3f6d7a16 ("powerpc/entry: Disable interrupts before irqentry_exit")
Reported-by: Venkat Rao Bagalkote <venkat88@linux.ibm.com>
Closes: https://lore.kernel.org/all/6f9bfb0f-b14c-468e-bb9f-c157d120d0dc@linux.ibm.com/
Signed-off-by: Mukesh Kumar Chaurasiya (IBM) <mkchauras@gmail.com>
---
 arch/powerpc/include/asm/entry-common.h | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/arch/powerpc/include/asm/entry-common.h b/arch/powerpc/include/asm/entry-common.h
index c5adb5006361..de64389b0815 100644
--- a/arch/powerpc/include/asm/entry-common.h
+++ b/arch/powerpc/include/asm/entry-common.h
@@ -270,7 +270,7 @@ static inline void arch_interrupt_exit_prepare(struct pt_regs *regs)
 	}
 
 	/* irqentry_exit expects to be called with interrupts disabled */
-	local_irq_disable();
+	hard_irq_disable();
 }
 
 static inline void arch_interrupt_async_enter_prepare(struct pt_regs *regs)
-- 
2.55.0

Re: [PATCH] powerpc/entry: Use hard_irq_disable() in arch_interrupt_exit_prepare()

[Venkat Rao Bagalkote]

On 12/08/26 8:50 pm, Mukesh Kumar Chaurasiya (IBM) wrote:
> commit 334f3f6d7a16 ("powerpc/entry: Disable interrupts before irqentry_exit")
> fixed a BUG in preempt_schedule_irq() by calling local_irq_disable()
> unconditionally in arch_interrupt_exit_prepare() before irqentry_exit().
> The fix is correct in intent but uses the wrong primitive for PPC64.
>
> On PPC64, local_irq_disable() only sets the soft-mask
> (irq_soft_mask = IRQS_DISABLED). It does not set PACA_IRQ_HARD_DIS in
> irq_happened and does not clear MSR[EE].
>
> This causes a continuous WARN_ON boot hang on Power11 pSeries LPARs
> using the dedicated-cede cpuidle path. When the CPU wakes from H_CEDE,
> interrupt_exit_kernel_prepare() calls replay_soft_interrupts(), which
> dispatches pending async handlers (timer_interrupt, do_IRQ) using the
> DEFINE_INTERRUPT_HANDLER_ASYNC macro. That macro calls
> arch_interrupt_async_exit_prepare() -> arch_interrupt_exit_prepare()
> before irqentry_exit(). With local_irq_disable(), PACA_IRQ_HARD_DIS
> is not set, but next_interrupt() unconditionally asserts it:
>
>    WARN_ON(!(local_paca->irq_happened & PACA_IRQ_HARD_DIS));
>
> This fires on every replayed interrupt, looping indefinitely and
> preventing boot completion.
>
> Fix this by replacing local_irq_disable() with hard_irq_disable().
> On PPC64, hard_irq_disable() sets irq_soft_mask to IRQS_ALL_DISABLED,
> sets PACA_IRQ_HARD_DIS in irq_happened, and clears MSR[EE] — satisfying
> all of:
>
>    - lockdep_assert_irqs_disabled() in irqentry_exit_to_kernel_mode()
>    - next_interrupt()'s WARN_ON(!(irq_happened & PACA_IRQ_HARD_DIS))
>    - preempt_schedule_irq()'s BUG_ON(!irqs_disabled())
>
> On PPC32/non-64, hard_irq_disable() is equivalent to local_irq_disable(),
> so there is no regression on those platforms.
>
> Fixes: 334f3f6d7a16 ("powerpc/entry: Disable interrupts before irqentry_exit")
> Reported-by: Venkat Rao Bagalkote <venkat88@linux.ibm.com>
> Closes: https://lore.kernel.org/all/6f9bfb0f-b14c-468e-bb9f-c157d120d0dc@linux.ibm.com/
> Signed-off-by: Mukesh Kumar Chaurasiya (IBM) <mkchauras@gmail.com>
> ---


Tested this, and it fixes the reported issue.

Tested-by: Venkat Rao Bagalkote <venkat88@linux.ibm.com>


Regards,

Venkat.


>   arch/powerpc/include/asm/entry-common.h | 2 +-
>   1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/arch/powerpc/include/asm/entry-common.h b/arch/powerpc/include/asm/entry-common.h
> index c5adb5006361..de64389b0815 100644
> --- a/arch/powerpc/include/asm/entry-common.h
> +++ b/arch/powerpc/include/asm/entry-common.h
> @@ -270,7 +270,7 @@ static inline void arch_interrupt_exit_prepare(struct pt_regs *regs)
>   	}
>   
>   	/* irqentry_exit expects to be called with interrupts disabled */
> -	local_irq_disable();
> +	hard_irq_disable();
>   }
>   
>   static inline void arch_interrupt_async_enter_prepare(struct pt_regs *regs)

Re: [PATCH] powerpc/entry: Use hard_irq_disable() in arch_interrupt_exit_prepare()

[Christophe Leroy (CS GROUP)]

Le 13/08/2026 à 08:36, Venkat Rao Bagalkote a écrit :
> 
> On 12/08/26 8:50 pm, Mukesh Kumar Chaurasiya (IBM) wrote:
>> commit 334f3f6d7a16 ("powerpc/entry: Disable interrupts before 
>> irqentry_exit")
>> fixed a BUG in preempt_schedule_irq() by calling local_irq_disable()
>> unconditionally in arch_interrupt_exit_prepare() before irqentry_exit().
>> The fix is correct in intent but uses the wrong primitive for PPC64.
>>
>> On PPC64, local_irq_disable() only sets the soft-mask
>> (irq_soft_mask = IRQS_DISABLED). It does not set PACA_IRQ_HARD_DIS in
>> irq_happened and does not clear MSR[EE].
>>
>> This causes a continuous WARN_ON boot hang on Power11 pSeries LPARs
>> using the dedicated-cede cpuidle path. When the CPU wakes from H_CEDE,
>> interrupt_exit_kernel_prepare() calls replay_soft_interrupts(), which
>> dispatches pending async handlers (timer_interrupt, do_IRQ) using the
>> DEFINE_INTERRUPT_HANDLER_ASYNC macro. That macro calls
>> arch_interrupt_async_exit_prepare() -> arch_interrupt_exit_prepare()
>> before irqentry_exit(). With local_irq_disable(), PACA_IRQ_HARD_DIS
>> is not set, but next_interrupt() unconditionally asserts it:
>>
>>    WARN_ON(!(local_paca->irq_happened & PACA_IRQ_HARD_DIS));
>>
>> This fires on every replayed interrupt, looping indefinitely and
>> preventing boot completion.
>>
>> Fix this by replacing local_irq_disable() with hard_irq_disable().
>> On PPC64, hard_irq_disable() sets irq_soft_mask to IRQS_ALL_DISABLED,
>> sets PACA_IRQ_HARD_DIS in irq_happened, and clears MSR[EE] — satisfying
>> all of:
>>
>>    - lockdep_assert_irqs_disabled() in irqentry_exit_to_kernel_mode()
>>    - next_interrupt()'s WARN_ON(!(irq_happened & PACA_IRQ_HARD_DIS))
>>    - preempt_schedule_irq()'s BUG_ON(!irqs_disabled())
>>
>> On PPC32/non-64, hard_irq_disable() is equivalent to local_irq_disable(),
>> so there is no regression on those platforms.
>>
>> Fixes: 334f3f6d7a16 ("powerpc/entry: Disable interrupts before 
>> irqentry_exit")
>> Reported-by: Venkat Rao Bagalkote <venkat88@linux.ibm.com>
>> Closes: https://eur01.safelinks.protection.outlook.com/? 
>> url=https%3A%2F%2Flore.kernel.org%2Fall%2F6f9bfb0f-b14c-468e-bb9f- 
>> c157d120d0dc%40linux.ibm.com%2F&data=05%7C02%7Cchristophe.leroy%40csgroup.eu%7Cf780f6a2abcf425c875808def90533e4%7C8b87af7d86474dc78df45f69a2011bb5%7C0%7C0%7C639221997929524168%7CUnknown%7CTWFpbGZsb3d8eyJFbXB0eU1hcGkiOnRydWUsIlYiOiIwLjAuMDAwMCIsIlAiOiJXaW4zMiIsIkFOIjoiTWFpbCIsIldUIjoyfQ%3D%3D%7C0%7C%7C%7C&sdata=kOer%2B610LkQs0ZKBn%2FutIB6j1bMoFasK4DmX4AEWOXA%3D&reserved=0
>> Signed-off-by: Mukesh Kumar Chaurasiya (IBM) <mkchauras@gmail.com>
>> ---
> 
> 
> Tested this, and it fixes the reported issue.
> 
> Tested-by: Venkat Rao Bagalkote <venkat88@linux.ibm.com>

Didn't you say yesterday [1] that the change doesn't fix the issue ? Did 
I miss something ?

[1] 
https://lore.kernel.org/all/2f7e6c34-7258-4b20-a38e-cedebccb835f@linux.ibm.com/


> 
> 
> Regards,
> 
> Venkat.
> 
> 
>>   arch/powerpc/include/asm/entry-common.h | 2 +-
>>   1 file changed, 1 insertion(+), 1 deletion(-)
>>
>> diff --git a/arch/powerpc/include/asm/entry-common.h b/arch/powerpc/ 
>> include/asm/entry-common.h
>> index c5adb5006361..de64389b0815 100644
>> --- a/arch/powerpc/include/asm/entry-common.h
>> +++ b/arch/powerpc/include/asm/entry-common.h
>> @@ -270,7 +270,7 @@ static inline void 
>> arch_interrupt_exit_prepare(struct pt_regs *regs)
>>       }
>>       /* irqentry_exit expects to be called with interrupts disabled */
>> -    local_irq_disable();
>> +    hard_irq_disable();
>>   }
>>   static inline void arch_interrupt_async_enter_prepare(struct pt_regs 
>> *regs)

Re: [PATCH] powerpc/entry: Use hard_irq_disable() in arch_interrupt_exit_prepare()

[Venkat Rao Bagalkote]

On 13/08/26 12:12 pm, Christophe Leroy (CS GROUP) wrote:
>
>
> Le 13/08/2026 à 08:36, Venkat Rao Bagalkote a écrit :
>>
>> On 12/08/26 8:50 pm, Mukesh Kumar Chaurasiya (IBM) wrote:
>>> commit 334f3f6d7a16 ("powerpc/entry: Disable interrupts before 
>>> irqentry_exit")
>>> fixed a BUG in preempt_schedule_irq() by calling local_irq_disable()
>>> unconditionally in arch_interrupt_exit_prepare() before 
>>> irqentry_exit().
>>> The fix is correct in intent but uses the wrong primitive for PPC64.
>>>
>>> On PPC64, local_irq_disable() only sets the soft-mask
>>> (irq_soft_mask = IRQS_DISABLED). It does not set PACA_IRQ_HARD_DIS in
>>> irq_happened and does not clear MSR[EE].
>>>
>>> This causes a continuous WARN_ON boot hang on Power11 pSeries LPARs
>>> using the dedicated-cede cpuidle path. When the CPU wakes from H_CEDE,
>>> interrupt_exit_kernel_prepare() calls replay_soft_interrupts(), which
>>> dispatches pending async handlers (timer_interrupt, do_IRQ) using the
>>> DEFINE_INTERRUPT_HANDLER_ASYNC macro. That macro calls
>>> arch_interrupt_async_exit_prepare() -> arch_interrupt_exit_prepare()
>>> before irqentry_exit(). With local_irq_disable(), PACA_IRQ_HARD_DIS
>>> is not set, but next_interrupt() unconditionally asserts it:
>>>
>>>    WARN_ON(!(local_paca->irq_happened & PACA_IRQ_HARD_DIS));
>>>
>>> This fires on every replayed interrupt, looping indefinitely and
>>> preventing boot completion.
>>>
>>> Fix this by replacing local_irq_disable() with hard_irq_disable().
>>> On PPC64, hard_irq_disable() sets irq_soft_mask to IRQS_ALL_DISABLED,
>>> sets PACA_IRQ_HARD_DIS in irq_happened, and clears MSR[EE] — satisfying
>>> all of:
>>>
>>>    - lockdep_assert_irqs_disabled() in irqentry_exit_to_kernel_mode()
>>>    - next_interrupt()'s WARN_ON(!(irq_happened & PACA_IRQ_HARD_DIS))
>>>    - preempt_schedule_irq()'s BUG_ON(!irqs_disabled())
>>>
>>> On PPC32/non-64, hard_irq_disable() is equivalent to 
>>> local_irq_disable(),
>>> so there is no regression on those platforms.
>>>
>>> Fixes: 334f3f6d7a16 ("powerpc/entry: Disable interrupts before 
>>> irqentry_exit")
>>> Reported-by: Venkat Rao Bagalkote <venkat88@linux.ibm.com>
>>> Closes: https://eur01.safelinks.protection.outlook.com/? 
>>> url=https%3A%2F%2Flore.kernel.org%2Fall%2F6f9bfb0f-b14c-468e-bb9f- 
>>> c157d120d0dc%40linux.ibm.com%2F&data=05%7C02%7Cchristophe.leroy%40csgroup.eu%7Cf780f6a2abcf425c875808def90533e4%7C8b87af7d86474dc78df45f69a2011bb5%7C0%7C0%7C639221997929524168%7CUnknown%7CTWFpbGZsb3d8eyJFbXB0eU1hcGkiOnRydWUsIlYiOiIwLjAuMDAwMCIsIlAiOiJXaW4zMiIsIkFOIjoiTWFpbCIsIldUIjoyfQ%3D%3D%7C0%7C%7C%7C&sdata=kOer%2B610LkQs0ZKBn%2FutIB6j1bMoFasK4DmX4AEWOXA%3D&reserved=0 
>>>
>>> Signed-off-by: Mukesh Kumar Chaurasiya (IBM) <mkchauras@gmail.com>
>>> ---
>>
>>
>> Tested this, and it fixes the reported issue.
>>
>> Tested-by: Venkat Rao Bagalkote <venkat88@linux.ibm.com>
>
> Didn't you say yesterday [1] that the change doesn't fix the issue ? 
> Did I miss something ?
>
> [1] 
> https://lore.kernel.org/all/2f7e6c34-7258-4b20-a38e-cedebccb835f@linux.ibm.com/ 
>
>
>
Hi Christophe,

I think there are two separate issues being mixed together here, both of 
which were reported by me.

The first issue is the early boot hang. I tested the patch in that 
context and reported that the boot hang still persisted.

The second issue is the WARN in __replay_soft_interrupts(). For that 
issue, the same patch fixes the problem, which is why I provided the 
Tested-by tag.

I believe the confusion comes from the fact that the same patch ended up 
being discussed in relation to both reports. My earlier comment that the 
patch did not fix the issue was referring to the boot hang, while my 
Tested-by was for the WARN in __replay_soft_interrupts().

So, to clarify:

Boot hang issue: not fixed by the patch.
WARN in __replay_soft_interrupts(): fixed by the patch.

Regards,
Venkat


>>
>>
>> Regards,
>>
>> Venkat.
>>
>>
>>> arch/powerpc/include/asm/entry-common.h | 2 +-
>>>   1 file changed, 1 insertion(+), 1 deletion(-)
>>>
>>> diff --git a/arch/powerpc/include/asm/entry-common.h b/arch/powerpc/ 
>>> include/asm/entry-common.h
>>> index c5adb5006361..de64389b0815 100644
>>> --- a/arch/powerpc/include/asm/entry-common.h
>>> +++ b/arch/powerpc/include/asm/entry-common.h
>>> @@ -270,7 +270,7 @@ static inline void 
>>> arch_interrupt_exit_prepare(struct pt_regs *regs)
>>>       }
>>>       /* irqentry_exit expects to be called with interrupts disabled */
>>> -    local_irq_disable();
>>> +    hard_irq_disable();
>>>   }
>>>   static inline void arch_interrupt_async_enter_prepare(struct 
>>> pt_regs *regs)
>

Re: [PATCH] powerpc/entry: Use hard_irq_disable() in arch_interrupt_exit_prepare()

[Shrikanth Hegde]

On 8/12/26 8:50 PM, Mukesh Kumar Chaurasiya (IBM) wrote:
> commit 334f3f6d7a16 ("powerpc/entry: Disable interrupts before irqentry_exit")
> fixed a BUG in preempt_schedule_irq() by calling local_irq_disable()
> unconditionally in arch_interrupt_exit_prepare() before irqentry_exit().
> The fix is correct in intent but uses the wrong primitive for PPC64.
> 
> On PPC64, local_irq_disable() only sets the soft-mask
> (irq_soft_mask = IRQS_DISABLED). It does not set PACA_IRQ_HARD_DIS in
> irq_happened and does not clear MSR[EE].
> 
> This causes a continuous WARN_ON boot hang on Power11 pSeries LPARs
> using the dedicated-cede cpuidle path. When the CPU wakes from H_CEDE,
> interrupt_exit_kernel_prepare() calls replay_soft_interrupts(), which
> dispatches pending async handlers (timer_interrupt, do_IRQ) using the
> DEFINE_INTERRUPT_HANDLER_ASYNC macro. That macro calls
> arch_interrupt_async_exit_prepare() -> arch_interrupt_exit_prepare()
> before irqentry_exit(). With local_irq_disable(), PACA_IRQ_HARD_DIS
> is not set, but next_interrupt() unconditionally asserts it:
> 
>    WARN_ON(!(local_paca->irq_happened & PACA_IRQ_HARD_DIS));
> 
> This fires on every replayed interrupt, looping indefinitely and
> preventing boot completion.
> 
> Fix this by replacing local_irq_disable() with hard_irq_disable().
> On PPC64, hard_irq_disable() sets irq_soft_mask to IRQS_ALL_DISABLED,
> sets PACA_IRQ_HARD_DIS in irq_happened, and clears MSR[EE] — satisfying
> all of:
> 
>    - lockdep_assert_irqs_disabled() in irqentry_exit_to_kernel_mode()
>    - next_interrupt()'s WARN_ON(!(irq_happened & PACA_IRQ_HARD_DIS))
>    - preempt_schedule_irq()'s BUG_ON(!irqs_disabled())
> 
> On PPC32/non-64, hard_irq_disable() is equivalent to local_irq_disable(),
> so there is no regression on those platforms.
> 

This is good explanation, but what i not understanding is,

why pattern of setting PACA_IRQ_HARD_DIS changed?
Previous code at interrupt_exit_kernel_prepare which did local_irq_disable too.

Please check where was PACA_IRQ_HARD_DIS set without GENERIC_ENTRY which was preventing
this from happening?


> Fixes: 334f3f6d7a16 ("powerpc/entry: Disable interrupts before irqentry_exit")
> Reported-by: Venkat Rao Bagalkote <venkat88@linux.ibm.com>
> Closes: https://lore.kernel.org/all/6f9bfb0f-b14c-468e-bb9f-c157d120d0dc@linux.ibm.com/
> Signed-off-by: Mukesh Kumar Chaurasiya (IBM) <mkchauras@gmail.com>
> ---
>   arch/powerpc/include/asm/entry-common.h | 2 +-
>   1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/arch/powerpc/include/asm/entry-common.h b/arch/powerpc/include/asm/entry-common.h
> index c5adb5006361..de64389b0815 100644
> --- a/arch/powerpc/include/asm/entry-common.h
> +++ b/arch/powerpc/include/asm/entry-common.h
> @@ -270,7 +270,7 @@ static inline void arch_interrupt_exit_prepare(struct pt_regs *regs)
>   	}
>   
>   	/* irqentry_exit expects to be called with interrupts disabled */
> -	local_irq_disable();
> +	hard_irq_disable();
>   }
>   
>   static inline void arch_interrupt_async_enter_prepare(struct pt_regs *regs)

Re: [PATCH] powerpc/entry: Use hard_irq_disable() in arch_interrupt_exit_prepare()

[Mukesh Kumar Chaurasiya]

On Fri, Aug 14, 2026 at 11:06:43AM +0530, Shrikanth Hegde wrote:
[...]
> This is good explanation, but what i not understanding is,
> 
> why pattern of setting PACA_IRQ_HARD_DIS changed?
> Previous code at interrupt_exit_kernel_prepare which did local_irq_disable too.
> 
> Please check where was PACA_IRQ_HARD_DIS set without GENERIC_ENTRY which was preventing
> this from happening?

That's an excellent point. I think we are looking at this incorrectly,
If this is related to the nested soft replay interrupt than this whole 
dynamics changes, local_irq_disable will work for the actual interrupt
but when we go nested something is telling that the nested interrupt
that interrupts are enabled. Let me look at this more deeply.

Regards,
Mukesh

Re: [PATCH] powerpc/entry: Use hard_irq_disable() in arch_interrupt_exit_prepare()

[Mukesh Kumar Chaurasiya]

On Fri, Aug 14, 2026 at 11:42:22AM +0530, Mukesh Kumar Chaurasiya wrote:
> On Fri, Aug 14, 2026 at 11:06:43AM +0530, Shrikanth Hegde wrote:
> [...]
> > This is good explanation, but what i not understanding is,
> > 
> > why pattern of setting PACA_IRQ_HARD_DIS changed?
> > Previous code at interrupt_exit_kernel_prepare which did local_irq_disable too.
> > 
> > Please check where was PACA_IRQ_HARD_DIS set without GENERIC_ENTRY which was preventing
> > this from happening?
> 
> That's an excellent point. I think we are looking at this incorrectly,
> If this is related to the nested soft replay interrupt than this whole 
> dynamics changes, local_irq_disable will work for the actual interrupt
> but when we go nested something is telling that the nested interrupt
> that interrupts are enabled. Let me look at this more deeply.
> 
> Regards,
> Mukesh

Hey Venkat,

Can you try this diff,

diff --git a/arch/powerpc/kernel/irq_64.c b/arch/powerpc/kernel/irq_64.c
index d5c48d1b0a31..2fbfebef74fe 100644
--- a/arch/powerpc/kernel/irq_64.c
+++ b/arch/powerpc/kernel/irq_64.c
@@ -117,7 +117,7 @@ static __no_kcsan void __replay_soft_interrupts(void)
 	local_paca->irq_happened |= PACA_IRQ_REPLAYING;
 
 	ppc_save_regs(&regs);
-	regs.softe = IRQS_ENABLED;
+	regs.softe = IRQS_DISABLED;
 	regs.msr |= MSR_EE;
 
 	/*

Re: [PATCH] powerpc/entry: Use hard_irq_disable() in arch_interrupt_exit_prepare()

[Venkat Rao Bagalkote]

On 15/08/26 10:27 am, Mukesh Kumar Chaurasiya wrote:
> On Fri, Aug 14, 2026 at 11:42:22AM +0530, Mukesh Kumar Chaurasiya wrote:
>> On Fri, Aug 14, 2026 at 11:06:43AM +0530, Shrikanth Hegde wrote:
>> [...]
>>> This is good explanation, but what i not understanding is,
>>>
>>> why pattern of setting PACA_IRQ_HARD_DIS changed?
>>> Previous code at interrupt_exit_kernel_prepare which did local_irq_disable too.
>>>
>>> Please check where was PACA_IRQ_HARD_DIS set without GENERIC_ENTRY which was preventing
>>> this from happening?
>> That's an excellent point. I think we are looking at this incorrectly,
>> If this is related to the nested soft replay interrupt than this whole
>> dynamics changes, local_irq_disable will work for the actual interrupt
>> but when we go nested something is telling that the nested interrupt
>> that interrupts are enabled. Let me look at this more deeply.
>>
>> Regards,
>> Mukesh
> Hey Venkat,
>
> Can you try this diff,
>
> diff --git a/arch/powerpc/kernel/irq_64.c b/arch/powerpc/kernel/irq_64.c
> index d5c48d1b0a31..2fbfebef74fe 100644
> --- a/arch/powerpc/kernel/irq_64.c
> +++ b/arch/powerpc/kernel/irq_64.c
> @@ -117,7 +117,7 @@ static __no_kcsan void __replay_soft_interrupts(void)
>   	local_paca->irq_happened |= PACA_IRQ_REPLAYING;
>   
>   	ppc_save_regs(&regs);
> -	regs.softe = IRQS_ENABLED;
> +	regs.softe = IRQS_DISABLED;
>   	regs.msr |= MSR_EE;
>   
>   	/*
>
Hello Mukesh,

With the proposed change, I still the issue.

[    0.742633] ------------[ cut here ]------------
[    0.742633] WARNING: arch/powerpc/kernel/irq_64.c:75 at 
__replay_soft_interrupts+0x104/0x220, CPU#6: swapper/0/1
[    0.742637] Modules linked in:
[    0.742638] CPU: 6 UID: 0 PID: 1 Comm: swapper/0 Tainted: G   W      
      7.2.0-rc7-dirty #25 PREEMPT
[    0.742639] Tainted: [W]=WARN
[    0.742640] Hardware name: IBM,9080-HEX Power11 (architected) 
0x820200 0xf000007 of:IBM,FW1110.01 (NH1110_069) hv:phyp pSeries
[    0.742641] NIP:  c00000000003a384 LR: c00000000003a360 CTR: 
c000000000029f00
[    0.742642] REGS: c000000009757410 TRAP: 0700   Tainted: G W          
   (7.2.0-rc7-dirty)
[    0.742643] MSR:  8000000002021033 <SF,VEC,ME,IR,DR,RI,LE> CR: 
88024824  XER: 00000003
[    0.742646] CFAR: c00000000002a708 IRQMASK: 1
[    0.742646] GPR00: c00000000003a360 c0000000097576b0 c000000001b28100 
c0000000097576d8
[    0.742646] GPR04: 0000000000000000 0000000000000001 c00000000968d200 
c0000000096eb200
[    0.742646] GPR08: 0000000000000001 0000000000000041 0000000000000001 
000000002c1b8100
[    0.742646] GPR12: c000000000029f00 c0000005ffff8f00 0000000000000000 
c00000000968d200
[    0.742646] GPR16: c000000002f3aaf8 0000000000000000 c00000000284e138 
0000000000000000
[    0.742646] GPR20: c00000000303aaf8 c00000000303ade8 0000000000000001 
0000000000000000
[    0.742646] GPR24: c00000000303ae08 0000000000000000 0000000000000000 
0000000000000002
[    0.742646] GPR28: 0000000000000003 fcffffffffffffff fcffffffffffffff 
c00000000968d200
[    0.742662] NIP [c00000000003a384] __replay_soft_interrupts+0x104/0x220
[    0.742665] LR [c00000000003a360] __replay_soft_interrupts+0xe0/0x220
[    0.742668] Call Trace:
[    0.742668] [c0000000097576b0] [c00000000003a360] 
__replay_soft_interrupts+0xe0/0x220 (unreliable)
[    0.742672] [c000000009757860] [c00000000003a694] 
arch_local_irq_restore+0x1f4/0x2d8
[    0.742675] [c0000000097578b0] [c0000000002face0] 
console_flush_all+0x3ec/0x558
[    0.742676] [c000000009757a00] [c0000000002faee4] 
console_unlock+0x98/0x1d8
[    0.742678] [c000000009757a80] [c0000000002fc698] 
vprintk_emit+0x2c0/0x3f4
[    0.742680] [c000000009757af0] [c0000000002fdc70] vprintk+0x30/0x7c
[    0.742682] [c000000009757b10] [c0000000002f6c78] _printk+0x3c/0x50
[    0.742683] [c000000009757b30] [c00000000205d814] 
load_system_certificate_list+0x24/0x5c
[    0.742685] [c000000009757b90] [c00000000001111c] 
do_one_initcall+0x5c/0x3f0
[    0.742687] [c000000009757c70] [c00000000200684c] 
do_initcalls+0x11c/0x270
[    0.742689] [c000000009757d30] [c000000002006c78] 
kernel_init_freeable+0x228/0x3c0
[    0.742690] [c000000009757de0] [c000000000011600] kernel_init+0x30/0x260

[    0.742692] [c000000009757e50] [c00000000000df7c] 
ret_from_kernel_user_thread+0x14/0x1c


Regards,

Venkat.

Re: [PATCH] powerpc/entry: Use hard_irq_disable() in arch_interrupt_exit_prepare()

[Mukesh Kumar Chaurasiya]

On Wed, Aug 19, 2026 at 11:24:40AM +0530, Venkat Rao Bagalkote wrote:
> 
[...]
> > Hey Venkat,
> > 
> > Can you try this diff,
> > 
> > diff --git a/arch/powerpc/kernel/irq_64.c b/arch/powerpc/kernel/irq_64.c
> > index d5c48d1b0a31..2fbfebef74fe 100644
> > --- a/arch/powerpc/kernel/irq_64.c
> > +++ b/arch/powerpc/kernel/irq_64.c
> > @@ -117,7 +117,7 @@ static __no_kcsan void __replay_soft_interrupts(void)
> >   	local_paca->irq_happened |= PACA_IRQ_REPLAYING;
> >   	ppc_save_regs(&regs);
> > -	regs.softe = IRQS_ENABLED;
> > +	regs.softe = IRQS_DISABLED;
> >   	regs.msr |= MSR_EE;
> >   	/*
> > 
> Hello Mukesh,
> 
> With the proposed change, I still the issue.
> 
> [    0.742633] ------------[ cut here ]------------
> [    0.742633] WARNING: arch/powerpc/kernel/irq_64.c:75 at
> __replay_soft_interrupts+0x104/0x220, CPU#6: swapper/0/1
> [    0.742637] Modules linked in:
> [    0.742638] CPU: 6 UID: 0 PID: 1 Comm: swapper/0 Tainted: G   W         
>  7.2.0-rc7-dirty #25 PREEMPT
> [    0.742639] Tainted: [W]=WARN
> [    0.742640] Hardware name: IBM,9080-HEX Power11 (architected) 0x820200
> 0xf000007 of:IBM,FW1110.01 (NH1110_069) hv:phyp pSeries
> [    0.742641] NIP:  c00000000003a384 LR: c00000000003a360 CTR:
> c000000000029f00
> [    0.742642] REGS: c000000009757410 TRAP: 0700   Tainted: G W           
> (7.2.0-rc7-dirty)
> [    0.742643] MSR:  8000000002021033 <SF,VEC,ME,IR,DR,RI,LE> CR: 88024824 
> XER: 00000003
> [    0.742646] CFAR: c00000000002a708 IRQMASK: 1
> [    0.742646] GPR00: c00000000003a360 c0000000097576b0 c000000001b28100
> c0000000097576d8
> [    0.742646] GPR04: 0000000000000000 0000000000000001 c00000000968d200
> c0000000096eb200
> [    0.742646] GPR08: 0000000000000001 0000000000000041 0000000000000001
> 000000002c1b8100
> [    0.742646] GPR12: c000000000029f00 c0000005ffff8f00 0000000000000000
> c00000000968d200
> [    0.742646] GPR16: c000000002f3aaf8 0000000000000000 c00000000284e138
> 0000000000000000
> [    0.742646] GPR20: c00000000303aaf8 c00000000303ade8 0000000000000001
> 0000000000000000
> [    0.742646] GPR24: c00000000303ae08 0000000000000000 0000000000000000
> 0000000000000002
> [    0.742646] GPR28: 0000000000000003 fcffffffffffffff fcffffffffffffff
> c00000000968d200
> [    0.742662] NIP [c00000000003a384] __replay_soft_interrupts+0x104/0x220
> [    0.742665] LR [c00000000003a360] __replay_soft_interrupts+0xe0/0x220
> [    0.742668] Call Trace:
> [    0.742668] [c0000000097576b0] [c00000000003a360]
> __replay_soft_interrupts+0xe0/0x220 (unreliable)
> [    0.742672] [c000000009757860] [c00000000003a694]
> arch_local_irq_restore+0x1f4/0x2d8
> [    0.742675] [c0000000097578b0] [c0000000002face0]
> console_flush_all+0x3ec/0x558
> [    0.742676] [c000000009757a00] [c0000000002faee4]
> console_unlock+0x98/0x1d8
> [    0.742678] [c000000009757a80] [c0000000002fc698]
> vprintk_emit+0x2c0/0x3f4
> [    0.742680] [c000000009757af0] [c0000000002fdc70] vprintk+0x30/0x7c
> [    0.742682] [c000000009757b10] [c0000000002f6c78] _printk+0x3c/0x50
> [    0.742683] [c000000009757b30] [c00000000205d814]
> load_system_certificate_list+0x24/0x5c
> [    0.742685] [c000000009757b90] [c00000000001111c]
> do_one_initcall+0x5c/0x3f0
> [    0.742687] [c000000009757c70] [c00000000200684c]
> do_initcalls+0x11c/0x270
> [    0.742689] [c000000009757d30] [c000000002006c78]
> kernel_init_freeable+0x228/0x3c0
> [    0.742690] [c000000009757de0] [c000000000011600] kernel_init+0x30/0x260
> 
> [    0.742692] [c000000009757e50] [c00000000000df7c]
> ret_from_kernel_user_thread+0x14/0x1c
> 
> 
> Regards,
> 
> Venkat.
> 

Hey Venkat, 
Thanks for verifying.

The regs.softe = IRQS_DISABLED change only prevents 
irqentry_exit_cond_resched() preemption path from running — it does nothing
about PACA_IRQ_HARD_DIS being cleared by the handler and not restored.
hard_irq_disable() fixes both: it atomically sets PACA_IRQ_HARD_DIS, sets
irq_soft_mask = IRQS_ALL_DISABLED, and clears MSR[EE], leaving a fully
consistent disabled state that next_interrupt() expects, regardless of
which entry path (idle wakeup or irqrestore) triggered the replay.

To answer's shrikanth question
it worked before because there was literally no interrupt-disabling code
on the handler exit path during replay. The new GENERIC_ENTRY
infrastructure brought a real exit sequence with it, and that sequence
needs hard_irq_disable() — not local_irq_disable() — to keep PPC64's
two-level interrupt state (irq_soft_mask + PACA_IRQ_HARD_DIS) consistent.

Hey Madhavan,
I think we are ok with this patch if there are no more objections from
anyone.

Regards,
Mukesh

Re: [PATCH] powerpc/entry: Use hard_irq_disable() in arch_interrupt_exit_prepare()

[Shrikanth Hegde]

On 8/19/26 2:16 PM, Mukesh Kumar Chaurasiya wrote:
> On Wed, Aug 19, 2026 at 11:24:40AM +0530, Venkat Rao Bagalkote wrote:
>>
> [...]
>>> Hey Venkat,
>>>
>>> Can you try this diff,
>>>
>>> diff --git a/arch/powerpc/kernel/irq_64.c b/arch/powerpc/kernel/irq_64.c
>>> index d5c48d1b0a31..2fbfebef74fe 100644
>>> --- a/arch/powerpc/kernel/irq_64.c
>>> +++ b/arch/powerpc/kernel/irq_64.c
>>> @@ -117,7 +117,7 @@ static __no_kcsan void __replay_soft_interrupts(void)
>>>    	local_paca->irq_happened |= PACA_IRQ_REPLAYING;
>>>    	ppc_save_regs(&regs);
>>> -	regs.softe = IRQS_ENABLED;
>>> +	regs.softe = IRQS_DISABLED;
>>>    	regs.msr |= MSR_EE;
>>>    	/*
>>>
>> Hello Mukesh,
>>
>> With the proposed change, I still the issue.
>>
>> [    0.742633] ------------[ cut here ]------------
>> [    0.742633] WARNING: arch/powerpc/kernel/irq_64.c:75 at
>> __replay_soft_interrupts+0x104/0x220, CPU#6: swapper/0/1
>> [    0.742637] Modules linked in:
>> [    0.742638] CPU: 6 UID: 0 PID: 1 Comm: swapper/0 Tainted: G   W
>>   7.2.0-rc7-dirty #25 PREEMPT
>> [    0.742639] Tainted: [W]=WARN
>> [    0.742640] Hardware name: IBM,9080-HEX Power11 (architected) 0x820200
>> 0xf000007 of:IBM,FW1110.01 (NH1110_069) hv:phyp pSeries
>> [    0.742641] NIP:  c00000000003a384 LR: c00000000003a360 CTR:
>> c000000000029f00
>> [    0.742642] REGS: c000000009757410 TRAP: 0700   Tainted: G W
>> (7.2.0-rc7-dirty)
>> [    0.742643] MSR:  8000000002021033 <SF,VEC,ME,IR,DR,RI,LE> CR: 88024824
>> XER: 00000003
>> [    0.742646] CFAR: c00000000002a708 IRQMASK: 1
>> [    0.742646] GPR00: c00000000003a360 c0000000097576b0 c000000001b28100
>> c0000000097576d8
>> [    0.742646] GPR04: 0000000000000000 0000000000000001 c00000000968d200
>> c0000000096eb200
>> [    0.742646] GPR08: 0000000000000001 0000000000000041 0000000000000001
>> 000000002c1b8100
>> [    0.742646] GPR12: c000000000029f00 c0000005ffff8f00 0000000000000000
>> c00000000968d200
>> [    0.742646] GPR16: c000000002f3aaf8 0000000000000000 c00000000284e138
>> 0000000000000000
>> [    0.742646] GPR20: c00000000303aaf8 c00000000303ade8 0000000000000001
>> 0000000000000000
>> [    0.742646] GPR24: c00000000303ae08 0000000000000000 0000000000000000
>> 0000000000000002
>> [    0.742646] GPR28: 0000000000000003 fcffffffffffffff fcffffffffffffff
>> c00000000968d200
>> [    0.742662] NIP [c00000000003a384] __replay_soft_interrupts+0x104/0x220
>> [    0.742665] LR [c00000000003a360] __replay_soft_interrupts+0xe0/0x220
>> [    0.742668] Call Trace:
>> [    0.742668] [c0000000097576b0] [c00000000003a360]
>> __replay_soft_interrupts+0xe0/0x220 (unreliable)
>> [    0.742672] [c000000009757860] [c00000000003a694]
>> arch_local_irq_restore+0x1f4/0x2d8
>> [    0.742675] [c0000000097578b0] [c0000000002face0]
>> console_flush_all+0x3ec/0x558
>> [    0.742676] [c000000009757a00] [c0000000002faee4]
>> console_unlock+0x98/0x1d8
>> [    0.742678] [c000000009757a80] [c0000000002fc698]
>> vprintk_emit+0x2c0/0x3f4
>> [    0.742680] [c000000009757af0] [c0000000002fdc70] vprintk+0x30/0x7c
>> [    0.742682] [c000000009757b10] [c0000000002f6c78] _printk+0x3c/0x50
>> [    0.742683] [c000000009757b30] [c00000000205d814]
>> load_system_certificate_list+0x24/0x5c
>> [    0.742685] [c000000009757b90] [c00000000001111c]
>> do_one_initcall+0x5c/0x3f0
>> [    0.742687] [c000000009757c70] [c00000000200684c]
>> do_initcalls+0x11c/0x270
>> [    0.742689] [c000000009757d30] [c000000002006c78]
>> kernel_init_freeable+0x228/0x3c0
>> [    0.742690] [c000000009757de0] [c000000000011600] kernel_init+0x30/0x260
>>
>> [    0.742692] [c000000009757e50] [c00000000000df7c]
>> ret_from_kernel_user_thread+0x14/0x1c
>>
>>
>> Regards,
>>
>> Venkat.
>>
> 
> Hey Venkat,
> Thanks for verifying.
> 
> The regs.softe = IRQS_DISABLED change only prevents
> irqentry_exit_cond_resched() preemption path from running — it does nothing
> about PACA_IRQ_HARD_DIS being cleared by the handler and not restored.
> hard_irq_disable() fixes both: it atomically sets PACA_IRQ_HARD_DIS, sets
> irq_soft_mask = IRQS_ALL_DISABLED, and clears MSR[EE], leaving a fully
> consistent disabled state that next_interrupt() expects, regardless of
> which entry path (idle wakeup or irqrestore) triggered the replay.
> 
> To answer's shrikanth question
> it worked before because there was literally no interrupt-disabling code
> on the handler exit path during replay. The new GENERIC_ENTRY
> infrastructure brought a real exit sequence with it, and that sequence
> needs hard_irq_disable() — not local_irq_disable() — to keep PPC64's
> two-level interrupt state (irq_soft_mask + PACA_IRQ_HARD_DIS) consistent.
> 
> Hey Madhavan,
> I think we are ok with this patch if there are no more objections from
> anyone.
> 

Venkat,

Can you collect vmcore with panic on warning enabled?

It maybe nested replay of soft interrupts which maybe causing problems 
here. We should see the regs state.

> Regards,
> Mukesh

Re: [PATCH] powerpc/entry: Use hard_irq_disable() in arch_interrupt_exit_prepare()

[Mukesh Kumar Chaurasiya]

On Wed, Aug 19, 2026 at 04:22:31PM +0530, Shrikanth Hegde wrote:
> 
> Can you collect vmcore with panic on warning enabled?
> 
> It maybe nested replay of soft interrupts which maybe causing problems here.
> We should see the regs state.
> 
> > Regards,
> > Mukesh
> 
Hey Venkat,

I have identified the root cause for this and discussed it with
Shrikanth also. We have agreed that the fix we have now is a proper fix
and why we got this issue now and not earlier. I'll send out a new
revision for this.

Regards,
Mukesh