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

On 07/09/26 10:57 pm, Shrikanth Hegde wrote:

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

quoted

On 07/09/26 2:04 pm, Michal Suchánek wrote:

quoted

Hello,

On Mon, Sep 07, 2026 at 12:30:58PM +0530, Venkat Rao Bagalkote wrote:

quoted

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  originally introduced !radxi_enabled() check in NMI 
wrapper path.

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

Hello Shrikanth,

Yes, you are right. commit 118178e62e2e, just consolidated NMI wrapper 
logic from arch/powerpc/kernel/mce.c into interrupt.h.

Tracing it further back, radix_enabled() check for pseries hash guest in 
real-mode NMI was originally introduced in

commit: 8d0e21012743 ("powerpc/mce: Avoid nmi_enter/exit in real mode on 
pseries hash")

I can add Fixes: 8d0e21012743, and send V2, if that works.

Regards,

Venkat.

quoted

Regards,

Venkat.

quoted

Thanks

Michal

quoted

Add the missing #include <asm/mmu.h> since early_radix_enabled() is
declared there.

Signed-off-by: Venkat Rao Bagalkote <redacted>
---
  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