[PATCH 1/3] KVM: SEV: mask CPUID[0x8000001F].eax according to supported features

[Paolo Bonzini]

Do not return the SEV-ES bit from KVM_GET_SUPPORTED_CPUID unless
the corresponding module parameter is 1, and clear the memory encryption
leaf completely if SEV is disabled.

Signed-off-by: Paolo Bonzini <pbonzini@xxxxxxxxxx>
---
 arch/x86/kvm/cpuid.c   | 5 ++++-
 arch/x86/kvm/cpuid.h   | 1 +
 arch/x86/kvm/svm/svm.c | 7 +++++++
 3 files changed, 12 insertions(+), 1 deletion(-)

diff --git a/arch/x86/kvm/cpuid.c b/arch/x86/kvm/cpuid.c
index 2ae061586677..d791d1f093ab 100644
--- a/arch/x86/kvm/cpuid.c
+++ b/arch/x86/kvm/cpuid.c
@@ -944,8 +944,11 @@ static inline int __do_cpuid_func(struct kvm_cpuid_array *array, u32 function)
 		break;
 	/* Support memory encryption cpuid if host supports it */
 	case 0x8000001F:
-		if (!boot_cpu_has(X86_FEATURE_SEV))
+		if (!kvm_cpu_cap_has(X86_FEATURE_SEV)) {
 			entry->eax = entry->ebx = entry->ecx = entry->edx = 0;
+			break;
+		}
+		cpuid_entry_override(entry, CPUID_8000_001F_EAX);
 		break;
 	/*Add support for Centaur's CPUID instruction*/
 	case 0xC0000000:
diff --git a/arch/x86/kvm/cpuid.h b/arch/x86/kvm/cpuid.h
index 888e88b42e8d..e873a60a4830 100644
--- a/arch/x86/kvm/cpuid.h
+++ b/arch/x86/kvm/cpuid.h
@@ -99,6 +99,7 @@ static const struct cpuid_reg reverse_cpuid[] = {
 	[CPUID_7_EDX]         = {         7, 0, CPUID_EDX},
 	[CPUID_7_1_EAX]       = {         7, 1, CPUID_EAX},
 	[CPUID_12_EAX]        = {0x00000012, 0, CPUID_EAX},
+	[CPUID_8000_001F_EAX] = {0x8000001F, 0, CPUID_EAX},
 };
 
 /*
diff --git a/arch/x86/kvm/svm/svm.c b/arch/x86/kvm/svm/svm.c
index cd8c333ed2dc..acdb8457289e 100644
--- a/arch/x86/kvm/svm/svm.c
+++ b/arch/x86/kvm/svm/svm.c
@@ -923,6 +923,13 @@ static __init void svm_set_cpu_caps(void)
 	if (boot_cpu_has(X86_FEATURE_LS_CFG_SSBD) ||
 	    boot_cpu_has(X86_FEATURE_AMD_SSBD))
 		kvm_cpu_cap_set(X86_FEATURE_VIRT_SSBD);
+
+	/* CPUID 0x8000001F */
+	if (sev) {
+		kvm_cpu_cap_set(X86_FEATURE_SEV);
+		if (sev_es)
+			kvm_cpu_cap_set(X86_FEATURE_SEV_ES);
+	}
 }
 
 static __init int svm_hardware_setup(void)
-- 
2.26.2