Re: [PATCH] powerpc/interrupt: Use early_radix_enabled() in NMI real-mode guard

[Venkat Rao Bagalkote <venkat88@linux.ibm.com>]

On 07/09/26 2:04 pm, Michal Suchánek wrote:
> Hello,
>
> On Mon, Sep 07, 2026 at 12:30:58PM +0530, Venkat Rao Bagalkote wrote:
>> radix_enabled() uses a jump label which is only valid after
>> mmu_feature_keys_init() is called. Before that point, on a pSeries
>> hash guest, early_check_vec5() clears MMU_FTR_TYPE_RADIX in
>> cur_cpu_spec->mmu_features but the jump label has not yet been patched,
>> so radix_enabled() incorrectly returns true.
>>
>> Replace radix_enabled() with early_radix_enabled() which does a plain
>> bitmask check against cur_cpu_spec->mmu_features and is correct at all
>> times, including before jump label initialization.
> Any Fixes: here?


Hello Michal,

Yes, this can have.

Fixes: 118178e62e2e ("powerpc: move NMI entry/exit code into wrapper")

As commit 118178e62e2e originally introduced !radxi_enabled() check in 
NMI wrapper path.


Regards,

Venkat.

>
> Thanks
>
> Michal
>
>> Add the missing #include <asm/mmu.h> since early_radix_enabled() is
>> declared there.
>>
>> Signed-off-by: Venkat Rao Bagalkote <venkat88@linux.ibm.com>
>> ---
>>   arch/powerpc/include/asm/interrupt.h | 5 +++--
>>   1 file changed, 3 insertions(+), 2 deletions(-)
>>
>> diff --git a/arch/powerpc/include/asm/interrupt.h b/arch/powerpc/include/asm/interrupt.h
>> index 1b45a49e9bed..36a654e780f7 100644
>> --- a/arch/powerpc/include/asm/interrupt.h
>> +++ b/arch/powerpc/include/asm/interrupt.h
>> @@ -71,6 +71,7 @@
>>   
>>   #include <asm/kprobes.h>
>>   #include <asm/runlatch.h>
>> +#include <asm/mmu.h>
>>   
>>   #ifdef CONFIG_PPC_IRQ_SOFT_MASK_DEBUG
>>   /*
>> @@ -290,7 +291,7 @@ interrupt_handler long func(struct pt_regs *regs)			\
>>   		state = irqentry_nmi_enter(regs);			\
>>   	} else if (IS_ENABLED(CONFIG_PPC_BOOK3S_64) &&			\
>>   		   firmware_has_feature(FW_FEATURE_LPAR) &&		\
>> -		   !radix_enabled()) {					\
>> +		   !early_radix_enabled()) {				\
>>   		/* no nmi_entry for a pseries hash guest		\
>>   		 * taking a real mode exception */			\
>>   	} else if (IS_ENABLED(CONFIG_KASAN)) {				\
>> @@ -307,7 +308,7 @@ interrupt_handler long func(struct pt_regs *regs)			\
>>   		irqentry_nmi_exit(regs, state);				\
>>   	} else if (IS_ENABLED(CONFIG_PPC_BOOK3S_64) &&			\
>>   		   firmware_has_feature(FW_FEATURE_LPAR) &&		\
>> -		   !radix_enabled()) {					\
>> +		   !early_radix_enabled()) {				\
>>   		/* no nmi_exit for a pseries hash guest			\
>>   		 * taking a real mode exception */			\
>>   	} else if (IS_ENABLED(CONFIG_KASAN)) {				\
>> -- 
>> 2.45.2
>>
>>