[PATCH v3] s390/cpacf: Unpoison instruction results

[PATCH v3] s390/cpacf: Unpoison instruction results

[Ilya Leoshkevich]

Stop KMSAN from complaining about CPACF outputs being uninitialized.

Do not unpoison variable-length parameter blocks: mapping function
codes (like CPACF_KIMD_SHA_256) to lengths will be ugly. So let the
callers do this once the need arises.

Also do not touch cpacf_kma(): this wrapper does not handle cc 1 and
cc2 at the moment and has to be reworked.

Reviewed-by: Harald Freudenberger <freude@linux.ibm.com>
Signed-off-by: Ilya Leoshkevich <iii@linux.ibm.com>
---

v2: https://lore.kernel.org/all/20260807122132.3592583-1-iii@linux.ibm.com/
v2 -> v3: Drop cpacf_kma() change, add R-b (Harald).

v1: https://lore.kernel.org/linux-s390/20260806190223.3292580-1-iii@linux.ibm.com/
v1 -> v2: Unpoison outputs of more instructions (Sashiko).

 arch/s390/include/asm/cpacf.h | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/arch/s390/include/asm/cpacf.h b/arch/s390/include/asm/cpacf.h
index a83683169d98d..6174552d856dc 100644
--- a/arch/s390/include/asm/cpacf.h
+++ b/arch/s390/include/asm/cpacf.h
@@ -301,6 +301,7 @@ static __always_inline void __cpacf_query(unsigned int opcode,
 					  cpacf_mask_t *mask)
 {
 	__cpacf_query_insn(opcode, mask, CPACF_FC_QUERY);
+	kmsan_unpoison_memory(mask, sizeof(*mask));
 }
 
 static __always_inline int __cpacf_check_opcode(unsigned int opcode)
@@ -370,6 +371,7 @@ static __always_inline int cpacf_query_func(unsigned int opcode,
 static __always_inline void __cpacf_qai(unsigned int opcode, cpacf_qai_t *qai)
 {
 	__cpacf_query_insn(opcode, qai, CPACF_FC_QUERY_AUTH_INFO);
+	kmsan_unpoison_memory(qai, sizeof(*qai));
 }
 
 /**
@@ -422,6 +424,7 @@ static inline int cpacf_km(unsigned long func, void *param,
 		  [opc] "i" (CPACF_KM)
 		: "cc", "memory", "0", "1");
 
+	kmsan_unpoison_memory(dest, src_len - s.odd);
 	return src_len - s.odd;
 }
 
@@ -454,6 +457,7 @@ static inline int cpacf_kmc(unsigned long func, void *param,
 		  [opc] "i" (CPACF_KMC)
 		: "cc", "memory", "0", "1");
 
+	kmsan_unpoison_memory(dest, src_len - s.odd);
 	return src_len - s.odd;
 }
 
@@ -587,6 +591,7 @@ static inline int cpacf_kmctr(unsigned long func, void *param, u8 *dest,
 		  [opc] "i" (CPACF_KMCTR)
 		: "cc", "memory", "0", "1");
 
+	kmsan_unpoison_memory(dest, src_len - s.odd);
 	return src_len - s.odd;
 }
 
@@ -619,6 +624,7 @@ static inline void cpacf_prno(unsigned long func, void *param,
 		: [fc] "d" (func), [pba] "d" ((unsigned long)param),
 		  [seed] "d" (s.pair), [opc] "i" (CPACF_PRNO)
 		: "cc", "memory", "0", "1");
+	kmsan_unpoison_memory(dest, dest_len);
 }
 
 /**
-- 
2.55.0

Re: [PATCH v3] s390/cpacf: Unpoison instruction results

[Vasily Gorbik]

On Fri, Aug 14, 2026 at 02:15:25PM +0200, Ilya Leoshkevich wrote:
> Stop KMSAN from complaining about CPACF outputs being uninitialized.
> 
> Do not unpoison variable-length parameter blocks: mapping function
> codes (like CPACF_KIMD_SHA_256) to lengths will be ugly. So let the
> callers do this once the need arises.
> 
> Also do not touch cpacf_kma(): this wrapper does not handle cc 1 and
> cc2 at the moment and has to be reworked.
> 
> Reviewed-by: Harald Freudenberger <freude@linux.ibm.com>
> Signed-off-by: Ilya Leoshkevich <iii@linux.ibm.com>
> ---
> 
> v2: https://lore.kernel.org/all/20260807122132.3592583-1-iii@linux.ibm.com/
> v2 -> v3: Drop cpacf_kma() change, add R-b (Harald).
> 
> v1: https://lore.kernel.org/linux-s390/20260806190223.3292580-1-iii@linux.ibm.com/
> v1 -> v2: Unpoison outputs of more instructions (Sashiko).
> 
>  arch/s390/include/asm/cpacf.h | 6 ++++++
>  1 file changed, 6 insertions(+)

Applied, thank you!