[v18,104/121] KVM: TDX: Handle TDG.VP.VMCALL<GetTdVmCallInfo> hypercall

Commit Message

Isaku Yamahata Jan. 22, 2024, 11:54 p.m. UTC

From: Isaku Yamahata <[e-mail]>

Implement TDG.VP.VMCALL<GetTdVmCallInfo> hypercall.  If the input value is
zero, return success code and zero in output registers.

TDG.VP.VMCALL<GetTdVmCallInfo> hypercall is a subleaf of TDG.VP.VMCALL to
enumerate which TDG.VP.VMCALL sub leaves are supported.  This hypercall is
for future enhancement of the Guest-Host-Communication Interface (GHCI)
specification.  The GHCI version of 344426-001US defines it to require
input R12 to be zero and to return zero in output registers, R11, R12, R13,
and R14 so that guest TD enumerates no enhancement.

Signed-off-by: Isaku Yamahata <[e-mail]>
---
 arch/x86/kvm/vmx/tdx.c | 16 ++++++++++++++++
 1 file changed, 16 insertions(+)

Patch

diff --git a/arch/x86/kvm/vmx/tdx.c b/arch/x86/kvm/vmx/tdx.c
index 5a2b211a365c..9283d45ea4b8 100644
--- a/arch/x86/kvm/vmx/tdx.c
+++ b/arch/x86/kvm/vmx/tdx.c
@@ -1403,6 +1403,20 @@  static int tdx_emulate_wrmsr(struct kvm_vcpu *vcpu)
 	return 1;
 }
 
+static int tdx_get_td_vm_call_info(struct kvm_vcpu *vcpu)
+{
+	if (tdvmcall_a0_read(vcpu))
+		tdvmcall_set_return_code(vcpu, TDG_VP_VMCALL_INVALID_OPERAND);
+	else {
+		tdvmcall_set_return_code(vcpu, TDG_VP_VMCALL_SUCCESS);
+		kvm_r11_write(vcpu, 0);
+		tdvmcall_a0_write(vcpu, 0);
+		tdvmcall_a1_write(vcpu, 0);
+		tdvmcall_a2_write(vcpu, 0);
+	}
+	return 1;
+}
+
 static int handle_tdvmcall(struct kvm_vcpu *vcpu)
 {
 	if (tdvmcall_exit_type(vcpu))
@@ -1421,6 +1435,8 @@  static int handle_tdvmcall(struct kvm_vcpu *vcpu)
 		return tdx_emulate_rdmsr(vcpu);
 	case EXIT_REASON_MSR_WRITE:
 		return tdx_emulate_wrmsr(vcpu);
+	case TDG_VP_VMCALL_GET_TD_VM_CALL_INFO:
+		return tdx_get_td_vm_call_info(vcpu);
 	default:
 		break;
 	}