linux-kernel - [PATCH V8 12/44] mm/pkeys: Define PKS page table macros

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Date:   Thu, 27 Jan 2022 09:54:33 -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 12/44] mm/pkeys: Define PKS page table macros

From: Fenghua Yu <fenghua.yu@...el.com>

Kernel users will need a way to assign their pkey to pages.

Define _PAGE_PKEY() and PAGE_KERNEL_PKEY() to allow users to set a pkey
on a PTE.

Add documentation.

Co-developed-by: Ira Weiny <ira.weiny@...el.com>
Signed-off-by: Ira Weiny <ira.weiny@...el.com>
Signed-off-by: Fenghua Yu <fenghua.yu@...el.com>

---
Changes for V8
	Split out from the 'Add PKS kernel API' patch
	Include documentation in this patch
---
 Documentation/core-api/protection-keys.rst |  7 +++++++
 arch/x86/include/asm/pgtable_types.h       | 22 ++++++++++++++++++++++
 include/linux/pgtable.h                    |  4 ++++
 3 files changed, 33 insertions(+)

diff --git a/Documentation/core-api/protection-keys.rst b/Documentation/core-api/protection-keys.rst
index af283a1a9aa0..794b7dedc544 100644
--- a/Documentation/core-api/protection-keys.rst
+++ b/Documentation/core-api/protection-keys.rst
@@ -134,6 +134,13 @@ PKS Key Allocation
 .. kernel-doc:: include/linux/pks-keys.h
         :doc: PKS_KEY_ALLOCATION
 
+Adding Pages to a PKey protected domain
+---------------------------------------
+
+.. kernel-doc:: arch/x86/include/asm/pgtable_types.h
+        :doc: PKS_KEY_ASSIGNMENT
+
+
 MSR details
 -----------
 
diff --git a/arch/x86/include/asm/pgtable_types.h b/arch/x86/include/asm/pgtable_types.h
index 40497a9020c6..e1d4535b525e 100644
--- a/arch/x86/include/asm/pgtable_types.h
+++ b/arch/x86/include/asm/pgtable_types.h
@@ -71,6 +71,22 @@
 			 _PAGE_PKEY_BIT2 | \
 			 _PAGE_PKEY_BIT3)
 
+/**
+ * DOC: PKS_KEY_ASSIGNMENT
+ *
+ * The following macros are used to set a pkey value in a supervisor PTE.
+ *
+ * .. code-block:: c
+ *
+ *         #define _PAGE_KEY(pkey)
+ *         #define PAGE_KERNEL_PKEY(pkey)
+ */
+#ifdef CONFIG_ARCH_ENABLE_SUPERVISOR_PKEYS
+#define _PAGE_PKEY(pkey)	(_AT(pteval_t, pkey) << _PAGE_BIT_PKEY_BIT0)
+#else
+#define _PAGE_PKEY(pkey)	(_AT(pteval_t, 0))
+#endif
+
 #if defined(CONFIG_X86_64) || defined(CONFIG_X86_PAE)
 #define _PAGE_KNL_ERRATUM_MASK (_PAGE_DIRTY | _PAGE_ACCESSED)
 #else
@@ -226,6 +242,12 @@ enum page_cache_mode {
 #define PAGE_KERNEL_IO		__pgprot_mask(__PAGE_KERNEL_IO)
 #define PAGE_KERNEL_IO_NOCACHE	__pgprot_mask(__PAGE_KERNEL_IO_NOCACHE)
 
+#ifdef CONFIG_ARCH_ENABLE_SUPERVISOR_PKEYS
+#define PAGE_KERNEL_PKEY(pkey)	__pgprot_mask(__PAGE_KERNEL | _PAGE_PKEY(pkey))
+#else
+#define PAGE_KERNEL_PKEY(pkey) PAGE_KERNEL
+#endif
+
 #endif	/* __ASSEMBLY__ */
 
 /*         xwr */
diff --git a/include/linux/pgtable.h b/include/linux/pgtable.h
index bc8713a76e03..2864066e03ec 100644
--- a/include/linux/pgtable.h
+++ b/include/linux/pgtable.h
@@ -1510,6 +1510,10 @@ static inline bool arch_has_pfn_modify_check(void)
 # define PAGE_KERNEL_EXEC PAGE_KERNEL
 #endif
 
+#ifndef PAGE_KERNEL_PKEY
+#define PAGE_KERNEL_PKEY(pkey) PAGE_KERNEL
+#endif
+
 /*
  * Page Table Modification bits for pgtbl_mod_mask.
  *
-- 
2.31.1