linux-kernel - [PATCH v4 02/13] x86/cpufeature: Enumerate Key Locker feature

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Date:   Mon, 13 Dec 2021 16:52:01 -0800
From:   "Chang S. Bae" <chang.seok.bae@...el.com>
To:     tglx@...utronix.de, bp@...e.de, dave.hansen@...ux.intel.com,
        mingo@...nel.org, luto@...nel.org, x86@...nel.org,
        herbert@...dor.apana.org.au
Cc:     linux-kernel@...r.kernel.org, linux-crypto@...r.kernel.org,
        ebiggers@...nel.org, dan.j.williams@...el.com,
        charishma1.gairuboyina@...el.com, kumar.n.dwarakanath@...el.com,
        lalithambika.krishnakumar@...el.com, ravi.v.shankar@...el.com,
        chang.seok.bae@...el.com
Subject: [PATCH v4 02/13] x86/cpufeature: Enumerate Key Locker feature

Key Locker is a CPU feature to minimize exposure of clear-text key
material. An encoded form, called 'key handle', is referenced for data
encryption or decryption instead of accessing the clear text key.

A wrapping key loaded in the CPU's software-inaccessible state is used to
transform a user key into a key handle.

It supports Advanced Encryption Standard (AES) cipher algorithm with new
SIMD instruction set like its predecessor (AES-NI). So a new AES
implementation will follow in the kernel's crypto library.

Here add it to enumerate the hardware capability, but it will not be
shown in /proc/cpuinfo as userspace usage is not supported.

Make the feature depend on XMM2 as it comes with AES SIMD instructions.

Add X86_FEATURE_KEYLOCKER to the disabled features mask. It will be
enabled under a new config option.

Signed-off-by: Chang S. Bae <chang.seok.bae@...el.com>
Reviewed-by: Dan Williams <dan.j.williams@...el.com>
Cc: x86@...nel.org
Cc: linux-kernel@...r.kernel.org
---
Changes from RFC v2:
* Do not publish the feature flag to userspace.
* Update the changelog.

Changes from RFC v1:
* Updated the changelog.
---
 arch/x86/include/asm/cpufeatures.h          | 1 +
 arch/x86/include/asm/disabled-features.h    | 8 +++++++-
 arch/x86/include/uapi/asm/processor-flags.h | 2 ++
 arch/x86/kernel/cpu/cpuid-deps.c            | 1 +
 4 files changed, 11 insertions(+), 1 deletion(-)

diff --git a/arch/x86/include/asm/cpufeatures.h b/arch/x86/include/asm/cpufeatures.h
index d5b5f2ab87a0..e1964446bbe5 100644
--- a/arch/x86/include/asm/cpufeatures.h
+++ b/arch/x86/include/asm/cpufeatures.h
@@ -361,6 +361,7 @@
 #define X86_FEATURE_AVX512_VPOPCNTDQ	(16*32+14) /* POPCNT for vectors of DW/QW */
 #define X86_FEATURE_LA57		(16*32+16) /* 5-level page tables */
 #define X86_FEATURE_RDPID		(16*32+22) /* RDPID instruction */
+#define X86_FEATURE_KEYLOCKER		(16*32+23) /* "" Key Locker */
 #define X86_FEATURE_BUS_LOCK_DETECT	(16*32+24) /* Bus Lock detect */
 #define X86_FEATURE_CLDEMOTE		(16*32+25) /* CLDEMOTE instruction */
 #define X86_FEATURE_MOVDIRI		(16*32+27) /* MOVDIRI instruction */
diff --git a/arch/x86/include/asm/disabled-features.h b/arch/x86/include/asm/disabled-features.h
index 8f28fafa98b3..75e1e87640d4 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_X86_KEYLOCKER
+# define DISABLE_KEYLOCKER	0
+#else
+# define DISABLE_KEYLOCKER	(1<<(X86_FEATURE_KEYLOCKER & 31))
+#endif /* CONFIG_X86_KEYLOCKER */
+
 #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_KEYLOCKER)
 #define DISABLED_MASK17	0
 #define DISABLED_MASK18	0
 #define DISABLED_MASK19	0
diff --git a/arch/x86/include/uapi/asm/processor-flags.h b/arch/x86/include/uapi/asm/processor-flags.h
index bcba3c643e63..b958a95a0908 100644
--- a/arch/x86/include/uapi/asm/processor-flags.h
+++ b/arch/x86/include/uapi/asm/processor-flags.h
@@ -124,6 +124,8 @@
 #define X86_CR4_PCIDE		_BITUL(X86_CR4_PCIDE_BIT)
 #define X86_CR4_OSXSAVE_BIT	18 /* enable xsave and xrestore */
 #define X86_CR4_OSXSAVE		_BITUL(X86_CR4_OSXSAVE_BIT)
+#define X86_CR4_KEYLOCKER_BIT	19 /* enable Key Locker */
+#define X86_CR4_KEYLOCKER	_BITUL(X86_CR4_KEYLOCKER_BIT)
 #define X86_CR4_SMEP_BIT	20 /* enable SMEP support */
 #define X86_CR4_SMEP		_BITUL(X86_CR4_SMEP_BIT)
 #define X86_CR4_SMAP_BIT	21 /* enable SMAP support */
diff --git a/arch/x86/kernel/cpu/cpuid-deps.c b/arch/x86/kernel/cpu/cpuid-deps.c
index c881bcafba7d..abe7e04b27d9 100644
--- a/arch/x86/kernel/cpu/cpuid-deps.c
+++ b/arch/x86/kernel/cpu/cpuid-deps.c
@@ -78,6 +78,7 @@ static const struct cpuid_dep cpuid_deps[] = {
 	{ X86_FEATURE_XFD,			X86_FEATURE_XSAVES    },
 	{ X86_FEATURE_XFD,			X86_FEATURE_XGETBV1   },
 	{ X86_FEATURE_AMX_TILE,			X86_FEATURE_XFD       },
+	{ X86_FEATURE_KEYLOCKER,		X86_FEATURE_XMM2      },
 	{}
 };
 
-- 
2.17.1