[PATCH v7 097/102] KVM: TDX: Handle TDG.VP.VMCALL hypercall

isaku.yamahata
2022-06-27T22:04:13Z

From: Isaku Yamahata <isaku.yamahata@intel.com>

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 <isaku.yamahata@intel.com>
---
arch/x86/kvm/vmx/tdx.c | 16 ++++++++++++++++
1 file changed, 16 insertions(+)

diff --git a/arch/x86/kvm/vmx/tdx.c b/arch/x86/kvm/vmx/tdx.c
index d4ac573d9db3..b1a1a7d96f39 100644
--- a/arch/x86/kvm/vmx/tdx.c
+++ b/arch/x86/kvm/vmx/tdx.c
@@ -1203,6 +1203,20 @@ 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 tdx_report_fatal_error(struct kvm_vcpu *vcpu)
{
/*
@@ -1297,6 +1311,8 @@ 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);
case TDG_VP_VMCALL_REPORT_FATAL_ERROR:
return tdx_report_fatal_error(vcpu);
case TDG_VP_VMCALL_MAP_GPA:
--
2.25.1