[PATCH Part2 RFC v2 02/37] KVM: SVM: Provide the Hypervisor Feature support VMGEXIT

[Brijesh Singh <brijesh.singh@xxxxxxx>]

Version 2 of the GHCB specification introduced advertisement of features
that are supported by the Hypervisor.

Now that KVM supports the basic SEV-SNP, advertisement the support through
the hypervisor feature request MSR protocol and NAE VMGEXITs.

Signed-off-by: Brijesh Singh <brijesh.singh@xxxxxxx>
---
 arch/x86/kvm/svm/sev.c | 14 ++++++++++++++
 arch/x86/kvm/svm/svm.h |  1 +
 2 files changed, 15 insertions(+)

diff --git a/arch/x86/kvm/svm/sev.c b/arch/x86/kvm/svm/sev.c
index 7bf4c2354a5a..5f0034e0dacc 100644
--- a/arch/x86/kvm/svm/sev.c
+++ b/arch/x86/kvm/svm/sev.c
@@ -2174,6 +2174,7 @@ static int sev_es_validate_vmgexit(struct vcpu_svm *svm)
 	case SVM_VMGEXIT_AP_HLT_LOOP:
 	case SVM_VMGEXIT_AP_JUMP_TABLE:
 	case SVM_VMGEXIT_UNSUPPORTED_EVENT:
+	case SVM_VMGEXIT_HYPERVISOR_FEATURES:
 		break;
 	default:
 		goto vmgexit_err;
@@ -2431,6 +2432,13 @@ static int sev_handle_vmgexit_msr_protocol(struct vcpu_svm *svm)
 				  GHCB_MSR_INFO_MASK,
 				  GHCB_MSR_INFO_POS);
 		break;
+	case GHCB_MSR_HV_FEATURES_REQ: {
+		set_ghcb_msr_bits(svm, GHCB_HV_FEATURES_SUPPORTED,
+				GHCB_MSR_HV_FEATURES_MASK, GHCB_MSR_HV_FEATURES_POS);
+		set_ghcb_msr_bits(svm, GHCB_MSR_HV_FEATURES_RESP,
+				GHCB_MSR_INFO_MASK, GHCB_MSR_INFO_POS);
+		break;
+	}
 	case GHCB_MSR_TERM_REQ: {
 		u64 reason_set, reason_code;
 
@@ -2546,6 +2554,12 @@ int sev_handle_vmgexit(struct kvm_vcpu *vcpu)
 		ret = 1;
 		break;
 	}
+	case SVM_VMGEXIT_HYPERVISOR_FEATURES: {
+		ghcb_set_sw_exit_info_2(ghcb, GHCB_HV_FEATURES_SUPPORTED);
+
+		ret = 1;
+		break;
+	}
 	case SVM_VMGEXIT_UNSUPPORTED_EVENT:
 		vcpu_unimpl(vcpu,
 			    "vmgexit: unsupported event - exit_info_1=%#llx, exit_info_2=%#llx\n",
diff --git a/arch/x86/kvm/svm/svm.h b/arch/x86/kvm/svm/svm.h
index dad528d9f08f..2b0083753812 100644
--- a/arch/x86/kvm/svm/svm.h
+++ b/arch/x86/kvm/svm/svm.h
@@ -530,6 +530,7 @@ void svm_vcpu_unblocking(struct kvm_vcpu *vcpu);
 #define GHCB_VERSION_MAX	1ULL
 #define GHCB_VERSION_MIN	1ULL
 
+#define GHCB_HV_FEATURES_SUPPORTED	0
 
 extern unsigned int max_sev_asid;
 
-- 
2.17.1