[PATCH 3/5] KVM: x86: Expose Zhaoxin RNG2 CPUID feature

[Ewan Hai]

Advertise the Zhaoxin second-generation hardware RNG to guests viaCPUID 0xC0000001 EDX bits 22 (RNG2) and 23 (RNG2_EN).RNG2 is exposed by the REP XRNG2 instruction (encoding F3 0F A7 F8),documented in the Zhaoxin PadLock Instruction Reference, subsection 1.3("REP XRNG2"). It produces random bytes from two on-die RNG sourcesselectable via RAX bits[10:9] and an output mode (raw vs post-processed)controlled by RDX bits[1:0], providing high-quality entropy intendedfor cryptographic operations.REP XRNG2 is user-mode and available in all CPU modes, with noassociated MSR control. The RNG2 and RNG2_EN bits are redundant byhardware design (set or cleared together) and both serve purely asCPUID-level feature-presence reporting flags requiring no KVMemulation. Both bits are advertised because different software mayprobe either one when checking for RNG2 availability.Signed-off-by: Ewan Hai <ewanhai-oc@xxxxxxxxxxx>--- 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.cindex 8aaa3f20670e..087c41341240 100644--- a/arch/x86/kvm/cpuid.c+++ b/arch/x86/kvm/cpuid.c@@ -1286,6 +1286,8 @@ void kvm_initialize_cpu_caps(void) 		F(PHE_EN), 		F(PMM), 		F(PMM_EN),+		F(RNG2),+		F(RNG2_EN), 	);  	/*diff --git a/arch/x86/kvm/reverse_cpuid.h b/arch/x86/kvm/reverse_cpuid.hindex a1cd9116ef63..859ba43126d8 100644--- a/arch/x86/kvm/reverse_cpuid.h+++ b/arch/x86/kvm/reverse_cpuid.h@@ -81,6 +81,8 @@ #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)+#define X86_FEATURE_RNG2		KVM_X86_FEATURE(CPUID_C000_0001_EDX, 22)+#define X86_FEATURE_RNG2_EN		KVM_X86_FEATURE(CPUID_C000_0001_EDX, 23)  struct cpuid_reg { 	u32 function;-- 2.34.1




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