Balbir Singh [off-list ref] writes:

On Fri,  8 Sep 2017 15:44:54 -0700
Ram Pai [off-list ref] wrote:

quoted

cleanup the bits corresponding to a key in the AMR, and IAMR
register, when the key is newly allocated/activated or is freed.
We dont want some residual bits cause the hardware enforce
unintended behavior when the key is activated or freed.

Signed-off-by: Ram Pai <redacted>
---
 arch/powerpc/include/asm/pkeys.h |   12 ++++++++++++
 1 files changed, 12 insertions(+), 0 deletions(-)

diff --git a/arch/powerpc/include/asm/pkeys.h b/arch/powerpc/include/asm/pkeys.h
index 5a83ed7..53bf13b 100644
--- a/arch/powerpc/include/asm/pkeys.h
+++ b/arch/powerpc/include/asm/pkeys.h

@@ -54,6 +54,8 @@ static inline bool mm_pkey_is_allocated(struct mm_struct *mm, int pkey)
 		mm_set_pkey_is_allocated(mm, pkey));
 }
 
+extern void __arch_activate_pkey(int pkey);
+extern void __arch_deactivate_pkey(int pkey);
 /*
  * Returns a positive, 5-bit key on success, or -1 on failure.
  */

@@ -80,6 +82,12 @@ static inline int mm_pkey_alloc(struct mm_struct *mm)
 
 	ret = ffz((u32)mm_pkey_allocation_map(mm));
 	mm_set_pkey_allocated(mm, ret);
+
+	/*
+	 * enable the key in the hardware
+	 */
+	if (ret > 0)
+		__arch_activate_pkey(ret);
 	return ret;
 }
 

@@ -91,6 +99,10 @@ static inline int mm_pkey_free(struct mm_struct *mm, int pkey)
 	if (!mm_pkey_is_allocated(mm, pkey))
 		return -EINVAL;
 
+	/*
+	 * Disable the key in the hardware
+	 */
+	__arch_deactivate_pkey(pkey);
 	mm_set_pkey_free(mm, pkey);
 
 	return 0;

I think some of these patches can be merged, too much fine granularity
is hurting my ability to see the larger function/implementation.

Completely agree

-aneesh