linux-kernel - [PATCH V8 17/44] mm/pkeys: Introduce pks_mk

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Date:   Thu, 27 Jan 2022 09:54:38 -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>,
        linux-kernel@...r.kernel.org
Subject: [PATCH V8 17/44] mm/pkeys: Introduce pks_mk_noaccess()

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

After a valid access for a PKS protected page Users will need to change
the protections back to No Access for their Pkey

Define pks_mk_noaccess() to update the specified Pkey

Add documentation.

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

---
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/pkeys.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 e4a27b93f3d4..115afc67153f 100644
--- a/Documentation/core-api/protection-keys.rst
+++ b/Documentation/core-api/protection-keys.rst
@@ -145,7 +145,7 @@ Changing permissions of individual keys
 ---------------------------------------
 
 .. kernel-doc:: include/linux/pks-keys.h
-        :identifiers: pks_mk_readwrite
+        :identifiers: pks_mk_readwrite pks_mk_noaccess
 
 MSR details
 -----------
diff --git a/include/linux/pkeys.h b/include/linux/pkeys.h
index 73b554b99123..5f4965f5449b 100644
--- a/include/linux/pkeys.h
+++ b/include/linux/pkeys.h
@@ -57,6 +57,18 @@ static inline bool arch_pkeys_enabled(void)
 
 void pks_update_protection(int pkey, u32 protection);
 
+/**
+ * pks_mk_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_mk_noaccess(int pkey)
+{
+	pks_update_protection(pkey, PKEY_DISABLE_ACCESS);
+}
+
 /**
  * pks_mk_readwrite() - Make the domain Read/Write
  * @pkey: the pkey for which the access should change.
@@ -71,6 +83,7 @@ static inline void pks_mk_readwrite(int pkey)
 
 #else /* !CONFIG_ARCH_ENABLE_SUPERVISOR_PKEYS */
 
+static inline void pks_mk_noaccess(int pkey) {}
 static inline void pks_mk_readwrite(int pkey) {}
 
 #endif /* CONFIG_ARCH_ENABLE_SUPERVISOR_PKEYS */
-- 
2.31.1