[PATCH 3/4] x86: KVM: Advertise SM4 CPUID to userspace

[Tao Su <tao1.su@linux.intel.com>]

SM4 is a new set of instructions in the latest Intel platform
Clearwater Forest, which contains VSM4KEY4, VSM4RNDS4.

SM4 is enumerated via CPUID.(EAX=7,ECX=1):EAX[bit 2].

SM4 is on an expected-dense CPUID leaf and some other bits on this leaf
have kernel usages. Considering SM4 itself has no truly kernel usages,
hide this one in /proc/cpuinfo.

These instructions only operate in xmm, ymm registers and have no new VMX
controls, so there is no additional host enabling required for guests to
use these instructions, i.e. advertising SM4 CPUID to userspace is safe.

Tested-by: Jiaan Lu <jiaan.lu@intel.com>
Tested-by: Xuelian Guo <xuelian.guo@intel.com>
Signed-off-by: Tao Su <tao1.su@linux.intel.com>
---
 arch/x86/include/asm/cpufeatures.h | 1 +
 arch/x86/kvm/cpuid.c               | 2 +-
 2 files changed, 2 insertions(+), 1 deletion(-)

diff --git a/arch/x86/include/asm/cpufeatures.h b/arch/x86/include/asm/cpufeatures.h
index 460f4f93b039..d96277dceabf 100644
--- a/arch/x86/include/asm/cpufeatures.h
+++ b/arch/x86/include/asm/cpufeatures.h
@@ -319,6 +319,7 @@
 /* Intel-defined CPU features, CPUID level 0x00000007:1 (EAX), word 12 */
 #define X86_FEATURE_SHA512		(12*32+ 0) /* SHA512 instructions */
 #define X86_FEATURE_SM3			(12*32+ 1) /* SM3 instructions */
+#define X86_FEATURE_SM4			(12*32+ 2) /* SM4 instructions */
 #define X86_FEATURE_AVX_VNNI		(12*32+ 4) /* "avx_vnni" AVX VNNI instructions */
 #define X86_FEATURE_AVX512_BF16		(12*32+ 5) /* "avx512_bf16" AVX512 BFLOAT16 instructions */
 #define X86_FEATURE_CMPCCXADD           (12*32+ 7) /* CMPccXADD instructions */
diff --git a/arch/x86/kvm/cpuid.c b/arch/x86/kvm/cpuid.c
index e9f7489ba569..160b060121b2 100644
--- a/arch/x86/kvm/cpuid.c
+++ b/arch/x86/kvm/cpuid.c
@@ -698,7 +698,7 @@ void kvm_set_cpu_caps(void)
 		kvm_cpu_cap_set(X86_FEATURE_SPEC_CTRL_SSBD);
 
 	kvm_cpu_cap_mask(CPUID_7_1_EAX,
-		F(SHA512) | F(SM3) | F(AVX_VNNI) | F(AVX512_BF16) |
+		F(SHA512) | F(SM3) | F(SM4) | F(AVX_VNNI) | F(AVX512_BF16) |
 		F(CMPCCXADD) | F(FZRM) | F(FSRS) | F(FSRC) |
 		F(AMX_FP16) | F(AVX_IFMA) | F(LAM)
 	);
-- 
2.34.1