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. On rarely unexpected
hardware failure, the key could be lost.
Here enumerate this hardware capability. It will not be shown up in
/proc/cpuinfo as userspace usage is not supported. This is because
there is no ABI to coordinate the wrapping-key failure.
The feature supports Advanced Encryption Standard (AES) cipher
algorithm with new SIMD instruction set like its predecessor (AES-NI).
Mark the feature having dependency on XMM2 like AES-NI has. The new AES
implementation will be in the crypto library.
Add X86_FEATURE_KEYLOCKER to the disabled feature list. It will be
enabled by a new Kconfig option.
Signed-off-by: Chang S. Bae <chang.seok.bae@xxxxxxxxx>
Reviewed-by: Dan Williams <dan.j.williams@xxxxxxxxx>
---
Changes from v6:
* Massage the changelog -- re-organize the change descriptions
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* Do not publish the feature flag to userspace.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 f0337f7bcf16..dd30435af487 100644
--- a/arch/x86/include/asm/cpufeatures.h
+++ b/arch/x86/include/asm/cpufeatures.h
@@ -399,6 +399,7 @@
#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 da4054fbf533..14aa6dc3b846 100644
--- a/arch/x86/include/asm/disabled-features.h
+++ b/arch/x86/include/asm/disabled-features.h
@@ -38,6 +38,12 @@
# 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
@@ -150,7 +156,7 @@
#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 (DISABLE_IBT)
#define DISABLED_MASK19 (DISABLE_SEV_SNP)
diff --git a/arch/x86/include/uapi/asm/processor-flags.h b/arch/x86/include/uapi/asm/processor-flags.h
index f1a4adc78272..a24f7cb2cd68 100644
--- a/arch/x86/include/uapi/asm/processor-flags.h
+++ b/arch/x86/include/uapi/asm/processor-flags.h
@@ -128,6 +128,8 @@
#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 b7174209d855..820dcf35eca9 100644
--- a/arch/x86/kernel/cpu/cpuid-deps.c
+++ b/arch/x86/kernel/cpu/cpuid-deps.c
@@ -84,6 +84,7 @@ static const struct cpuid_dep cpuid_deps[] = {
{ X86_FEATURE_SHSTK, X86_FEATURE_XSAVES },
{ X86_FEATURE_FRED, X86_FEATURE_LKGS },
{ X86_FEATURE_FRED, X86_FEATURE_WRMSRNS },
+ { X86_FEATURE_KEYLOCKER, X86_FEATURE_XMM2 },
{}
};
--
2.34.1
