On 9/9/26 2:42 PM, 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.
The usage window where it goes wrong is:
early_setup:
configure_exceptions();
<exception can happen now, and could prepare/exit of corresponding
exception>
<those could use radix_enabled() >
setup_feature_keys();
<jump labels are setup and post this it is safe to use radix_enabled()>
But since common wrappers don't have the context of early or late,
using early_radix_enabled() is safer option.
Commit message could convey the same.
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.
If you have data, please put the values of both early_radix_enabled and
radix_enabled()
in hash/radix guests in the chaneglog to ensure replacing with early variant
is functionally safe.
Add the missing #include <asm/mmu.h> since early_radix_enabled() is
declared there.
Fixes: 8d0e21012743 ("powerpc/mce: Avoid nmi_enter/exit in real mode on pseries
hash")
Signed-off-by: Venkat Rao Bagalkote <[email protected]>
Reviewed-by: Mukesh Kumar Chaurasiya <[email protected]>
---
v2:
- Added Fixes: tag referencing commit 8d0e21012743.
- Included <asm/mmu.h> in alphabetical order.
- Added Reviewed-by tag from Mukesh.
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..355f6bbf9894 100644
--- a/arch/powerpc/include/asm/interrupt.h
+++ b/arch/powerpc/include/asm/interrupt.h
@@ -70,6 +70,7 @@
#include <linux/irq-entry-common.h>
#include <asm/kprobes.h>
+#include <asm/mmu.h>
#include <asm/runlatch.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)) { \
