KVM: TDX: Exit to userspace for SetupEventNotifyInterrupt

JIRA: https://issues.redhat.com/browse/RHEL-47242

commit 4580dbe
Author: Paolo Bonzini <pbonzini@redhat.com>
Date:   Fri Jun 20 13:28:08 2025 -0400

    KVM: TDX: Exit to userspace for SetupEventNotifyInterrupt

    Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

Signed-off-by: Maxim Levitsky <mlevitsk@redhat.com>

Author: Maxim Levitsky

Documentation/virt/kvm/api.rst

@@ -7184,6 +7184,10 @@ The valid value for 'flags' is:
 					u64 leaf;
 					u64 r11, r12, r13, r14;
 				} get_tdvmcall_info;
+				struct {
+					u64 ret;
+					u64 vector;
+				} setup_event_notify;
 			};
 		} tdx;
 
@@ -7214,6 +7218,9 @@ status of TDVMCALLs.  The output values for the given leaf should be
 placed in fields from ``r11`` to ``r14`` of the ``get_tdvmcall_info``
 field of the union.
 
+* ``TDVMCALL_SETUP_EVENT_NOTIFY_INTERRUPT``: the guest has requested to
+set up a notification interrupt for vector ``vector``.
+
 KVM may add support for more values in the future that may cause a userspace
 exit, even without calls to ``KVM_ENABLE_CAP`` or similar.  In this case,
 it will enter with output fields already valid; in the common case, the

arch/x86/include/asm/shared/tdx.h

@@ -37,6 +37,7 @@
 #define TDVMCALL_MAP_GPA		0x10001
 #define TDVMCALL_GET_QUOTE		0x10002
 #define TDVMCALL_REPORT_FATAL_ERROR	0x10003
+#define TDVMCALL_SETUP_EVENT_NOTIFY_INTERRUPT 0x10004ULL
 
 /*
  * TDG.VP.VMCALL Status Codes (returned in R10)

arch/x86/kvm/vmx/tdx.c

@@ -1530,6 +1530,27 @@ static int tdx_get_quote(struct kvm_vcpu *vcpu)
 	return 0;
 }
 
+static int tdx_setup_event_notify_interrupt(struct kvm_vcpu *vcpu)
+{
+	struct vcpu_tdx *tdx = to_tdx(vcpu);
+	u64 vector = tdx->vp_enter_args.r12;
+
+	if (vector < 32 || vector > 255) {
+		tdvmcall_set_return_code(vcpu, TDVMCALL_STATUS_INVALID_OPERAND);
+		return 1;
+	}
+
+	vcpu->run->exit_reason = KVM_EXIT_TDX;
+	vcpu->run->tdx.flags = 0;
+	vcpu->run->tdx.nr = TDVMCALL_SETUP_EVENT_NOTIFY_INTERRUPT;
+	vcpu->run->tdx.setup_event_notify.ret = TDVMCALL_STATUS_SUBFUNC_UNSUPPORTED;
+	vcpu->run->tdx.setup_event_notify.vector = vector;
+
+	vcpu->arch.complete_userspace_io = tdx_complete_simple;
+
+	return 0;
+}
+
 static int handle_tdvmcall(struct kvm_vcpu *vcpu)
 {
 	switch (tdvmcall_leaf(vcpu)) {
@@ -1541,6 +1562,8 @@ static int handle_tdvmcall(struct kvm_vcpu *vcpu)
 		return tdx_get_td_vm_call_info(vcpu);
 	case TDVMCALL_GET_QUOTE:
 		return tdx_get_quote(vcpu);
+	case TDVMCALL_SETUP_EVENT_NOTIFY_INTERRUPT:
+		return tdx_setup_event_notify_interrupt(vcpu);
 	default:
 		break;
 	}

include/uapi/linux/kvm.h

@@ -467,6 +467,10 @@ struct kvm_run {
 					__u64 leaf;
 					__u64 r11, r12, r13, r14;
 				} get_tdvmcall_info;
+				struct {
+					__u64 ret;
+					__u64 vector;
+				} setup_event_notify;
 			};
 		} tdx;
 		/* Fix the size of the union. */