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

[Shrikanth Hegde <sshegde@linux.ibm.com>]

On 9/7/26 2:24 PM, Venkat Rao Bagalkote wrote:
> 
> 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.
> 
> 

looks like it did movement of code, rather than introducing.

> 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
>>>
>>>