[PATCH v1 2/5] KVM: x86: Expose Zhaoxin CCS (SM3 + SM4) CPUID feature

[Ewan Hai <ewandevelop@gmail.com>]

Advertise the Zhaoxin CCS (Chinese Cryptography Standard) feature to
guests via CPUID 0xC0000001 EDX bits 4 (CCS) and 5 (CCS_EN). CCS groups
two user-mode instructions for Chinese national cryptographic
primitives, documented in the Zhaoxin GMI Instruction Set Reference,
chapter 2 ("CCS instruction group"):

  - SM3 (encoding F3 0F A6 E8, subsection 2.1) implements the SM3 hash
    algorithm specified in GM/T 0004-2012. It supports two modes
    selected by RAX: auto-padding stream mode (RAX=0) and pre-padded
    block mode (RAX=-1).

  - SM4 (encoding F3 0F A7 F0, subsection 2.2) implements the SM4 block
    cipher specified in GM/T 0002-2012, supporting ECB / CBC / CFB /
    OFB / CTR modes via a control word in RAX, and CBC-MAC / CFB-MAC
    when RAX bit[11] is set.

Both instructions are user-mode and available in all CPU modes, with no
associated MSR control. The CCS and CCS_EN bits are redundant by
hardware design (set or cleared together) and both serve purely as
CPUID-level feature-presence reporting flags requiring no KVM
emulation. Both bits are advertised because different software may
probe either one when checking for CCS availability.

Signed-off-by: Ewan Hai <ewandevelop@gmail.com>
---
 arch/x86/kvm/cpuid.c         | 2 ++
 arch/x86/kvm/reverse_cpuid.h | 2 ++
 2 files changed, 4 insertions(+)

diff --git a/arch/x86/kvm/cpuid.c b/arch/x86/kvm/cpuid.c
index 1eb4b88aaa80..8aaa3f20670e 100644
--- a/arch/x86/kvm/cpuid.c
+++ b/arch/x86/kvm/cpuid.c
@@ -1276,6 +1276,8 @@ void kvm_initialize_cpu_caps(void)
 		F(SM2_EN),
 		F(XSTORE),
 		F(XSTORE_EN),
+		F(CCS),
+		F(CCS_EN),
 		F(XCRYPT),
 		F(XCRYPT_EN),
 		F(ACE2),
diff --git a/arch/x86/kvm/reverse_cpuid.h b/arch/x86/kvm/reverse_cpuid.h
index 7b55110cc046..a1cd9116ef63 100644
--- a/arch/x86/kvm/reverse_cpuid.h
+++ b/arch/x86/kvm/reverse_cpuid.h
@@ -79,6 +79,8 @@
 /* Zhaoxin/Centaur sub-features, CPUID level 0xC0000001 (EDX) */
 #define X86_FEATURE_SM2			KVM_X86_FEATURE(CPUID_C000_0001_EDX, 0)
 #define X86_FEATURE_SM2_EN		KVM_X86_FEATURE(CPUID_C000_0001_EDX, 1)
+#define X86_FEATURE_CCS			KVM_X86_FEATURE(CPUID_C000_0001_EDX, 4)
+#define X86_FEATURE_CCS_EN		KVM_X86_FEATURE(CPUID_C000_0001_EDX, 5)
 
 struct cpuid_reg {
 	u32 function;
-- 
2.34.1