KVM: SVM: Add support for SEV-ES GHCB MSR protocol function 0x100

The GHCB specification defines a GHCB MSR protocol using the lower
12-bits of the GHCB MSR (in the hypervisor this corresponds to the
GHCB GPA field in the VMCB).

Function 0x100 is a request for termination of the guest. The guest has
encountered some situation for which it has requested to be terminated.
The GHCB MSR value contains the reason for the request.
Signed-off-by: Tom Lendacky <thomas.lendacky@amd.com>
Message-Id: <f3a1f7850c75b6ea4101e15bbb4a3af1a203f1dc.1607620209.git.thomas.lendacky@amd.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

arch/x86/kvm/svm/sev.c

@@ -1570,6 +1570,19 @@ static int sev_handle_vmgexit_msr_protocol(struct vcpu_svm *svm)
 				  GHCB_MSR_INFO_POS);
 		break;
 	}
+	case GHCB_MSR_TERM_REQ: {
+		u64 reason_set, reason_code;
+
+		reason_set = get_ghcb_msr_bits(svm,
+					       GHCB_MSR_TERM_REASON_SET_MASK,
+					       GHCB_MSR_TERM_REASON_SET_POS);
+		reason_code = get_ghcb_msr_bits(svm,
+						GHCB_MSR_TERM_REASON_MASK,
+						GHCB_MSR_TERM_REASON_POS);
+		pr_info("SEV-ES guest requested termination: %#llx:%#llx\n",
+			reason_set, reason_code);
+		fallthrough;
+	}
 	default:
 		ret = -EINVAL;
 	}

arch/x86/kvm/svm/svm.h

@@ -543,6 +543,12 @@ void svm_vcpu_unblocking(struct kvm_vcpu *vcpu);
 #define GHCB_MSR_CPUID_REG_POS		30
 #define GHCB_MSR_CPUID_REG_MASK		0x3
 
+#define GHCB_MSR_TERM_REQ		0x100
+#define GHCB_MSR_TERM_REASON_SET_POS	12
+#define GHCB_MSR_TERM_REASON_SET_MASK	0xf
+#define GHCB_MSR_TERM_REASON_POS	16
+#define GHCB_MSR_TERM_REASON_MASK	0xff
+
 extern unsigned int max_sev_asid;
 
 static inline bool svm_sev_enabled(void)