linux-kernel - [PATCH V8 07/44] x86/pkeys: Add PKS CPU feature bit

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Date:   Thu, 27 Jan 2022 09:54:28 -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 07/44] x86/pkeys: Add PKS CPU feature bit

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

Protection Keys for Supervisor pages (PKS) enables fast, hardware thread
specific, manipulation of permission restrictions on supervisor page
mappings.  It uses the same mechanism of Protection Keys as those on
User mappings but applies that mechanism to supervisor mappings using a
supervisor specific MSR.

The CPU indicates support for PKS in bit 31 of the ECX register after a
cpuid instruction.

Add the defines for this bit and the boilerplate disable infrastructure
predicated on the Kconfig option.

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

---
Changes for V8
	Split this out into it's own patch
---
 arch/x86/include/asm/cpufeatures.h       | 1 +
 arch/x86/include/asm/disabled-features.h | 8 +++++++-
 2 files changed, 8 insertions(+), 1 deletion(-)

diff --git a/arch/x86/include/asm/cpufeatures.h b/arch/x86/include/asm/cpufeatures.h
index 6db4e2932b3d..b917605e9915 100644
--- a/arch/x86/include/asm/cpufeatures.h
+++ b/arch/x86/include/asm/cpufeatures.h
@@ -370,6 +370,7 @@
 #define X86_FEATURE_MOVDIR64B		(16*32+28) /* MOVDIR64B instruction */
 #define X86_FEATURE_ENQCMD		(16*32+29) /* ENQCMD and ENQCMDS instructions */
 #define X86_FEATURE_SGX_LC		(16*32+30) /* Software Guard Extensions Launch Control */
+#define X86_FEATURE_PKS			(16*32+31) /* Protection Keys for Supervisor pages */
 
 /* AMD-defined CPU features, CPUID level 0x80000007 (EBX), word 17 */
 #define X86_FEATURE_OVERFLOW_RECOV	(17*32+ 0) /* MCA overflow recovery support */
diff --git a/arch/x86/include/asm/disabled-features.h b/arch/x86/include/asm/disabled-features.h
index 8f28fafa98b3..66fdad8f3941 100644
--- a/arch/x86/include/asm/disabled-features.h
+++ b/arch/x86/include/asm/disabled-features.h
@@ -44,6 +44,12 @@
 # define DISABLE_OSPKE		(1<<(X86_FEATURE_OSPKE & 31))
 #endif /* CONFIG_X86_INTEL_MEMORY_PROTECTION_KEYS */
 
+#ifdef CONFIG_ARCH_ENABLE_SUPERVISOR_PKEYS
+# define DISABLE_PKS		0
+#else
+# define DISABLE_PKS		(1<<(X86_FEATURE_PKS & 31))
+#endif
+
 #ifdef CONFIG_X86_5LEVEL
 # define DISABLE_LA57	0
 #else
@@ -85,7 +91,7 @@
 #define DISABLED_MASK14	0
 #define DISABLED_MASK15	0
 #define DISABLED_MASK16	(DISABLE_PKU|DISABLE_OSPKE|DISABLE_LA57|DISABLE_UMIP| \
-			 DISABLE_ENQCMD)
+			 DISABLE_ENQCMD|DISABLE_PKS)
 #define DISABLED_MASK17	0
 #define DISABLED_MASK18	0
 #define DISABLED_MASK19	0
-- 
2.31.1