linux-kernel - [PATCH V9 18/45] mm/pkeys: Introduce pks_set

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Date:   Thu, 10 Mar 2022 09:19:52 -0800
From:   ira.weiny@...el.com
To:     Dave Hansen <dave.hansen@...ux.intel.com>,
        "H. Peter Anvin" <hpa@...or.com>,
        Dan Williams <dan.j.williams@...el.com>
Cc:     Ira Weiny <ira.weiny@...el.com>, Fenghua Yu <fenghua.yu@...el.com>,
        Rick Edgecombe <rick.p.edgecombe@...el.com>,
        "Shankar, Ravi V" <ravi.v.shankar@...el.com>,
        linux-kernel@...r.kernel.org
Subject: [PATCH V9 18/45] mm/pkeys: Introduce pks_set_noaccess()

From: Ira Weiny <ira.weiny@...el.com>

After a valid access consumers will want to change PKS protections back
to No Access for their pkey.

Define pks_set_noaccess() to update the specified pkey.

Add documentation.

Signed-off-by: Ira Weiny <ira.weiny@...el.com>

---
Changes for V9
	Move to pks.h
	Change pkey type to u8
	From 0day
		Fix documentation link
	From Dave Hansen
		use pkey
		s/pks_mk*/pks_set*/

Changes for V8
	Make the call inline
	Split this patch out from 'Add PKS kernel API'
	Include documentation in this patch
---
 Documentation/core-api/protection-keys.rst |  2 +-
 include/linux/pks.h                        | 13 +++++++++++++
 2 files changed, 14 insertions(+), 1 deletion(-)

diff --git a/Documentation/core-api/protection-keys.rst b/Documentation/core-api/protection-keys.rst
index e6564f5336b7..2ec35349ecfd 100644
--- a/Documentation/core-api/protection-keys.rst
+++ b/Documentation/core-api/protection-keys.rst
@@ -147,7 +147,7 @@ Changing permissions of individual keys
 ---------------------------------------
 
 .. kernel-doc:: include/linux/pks.h
-        :identifiers: pks_set_readwrite
+        :identifiers: pks_set_readwrite pks_set_noaccess
 
 MSR details
 ~~~~~~~~~~~
diff --git a/include/linux/pks.h b/include/linux/pks.h
index 8b705a937b19..9f18f8b4cbb1 100644
--- a/include/linux/pks.h
+++ b/include/linux/pks.h
@@ -10,6 +10,18 @@
 
 void pks_update_protection(u8 pkey, u8 protection);
 
+/**
+ * pks_set_noaccess() - Disable all access to the domain
+ * @pkey: the pkey for which the access should change.
+ *
+ * Disable all access to the domain specified by pkey.  This is not a global
+ * update and only affects the current running thread.
+ */
+static inline void pks_set_noaccess(u8 pkey)
+{
+	pks_update_protection(pkey, PKEY_DISABLE_ACCESS);
+}
+
 /**
  * pks_set_readwrite() - Make the domain Read/Write
  * @pkey: the pkey for which the access should change.
@@ -24,6 +36,7 @@ static inline void pks_set_readwrite(u8 pkey)
 
 #else /* !CONFIG_ARCH_ENABLE_SUPERVISOR_PKEYS */
 
+static inline void pks_set_noaccess(u8 pkey) {}
 static inline void pks_set_readwrite(u8 pkey) {}
 
 #endif /* CONFIG_ARCH_ENABLE_SUPERVISOR_PKEYS */
-- 
2.35.1