[PATCH 10/18] KVM: TDX: Handle TDG.VP.VMCALL hypercall

Binbin Wu
2024-12-10T00:48:25Z

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>
Signed-off-by: Binbin Wu <binbin.wu@linux.intel.com>
---
TDX "the rest" breakout:
- Use TDVMCALL_STATUS prefix for TDX call status codes (Binbin)

v19:
- rename TDG_VP_VMCALL_GET_TD_VM_CALL_INFO => TDVMCALL_GET_TD_VM_CALL_INFO
---
arch/x86/include/asm/shared/tdx.h | 1 +
arch/x86/kvm/vmx/tdx.c | 16 ++++++++++++++++
2 files changed, 17 insertions(+)

diff --git a/arch/x86/include/asm/shared/tdx.h b/arch/x86/include/asm/shared/tdx.h
index a602d081cf1c..192ae798b214 100644
--- a/arch/x86/include/asm/shared/tdx.h
+++ b/arch/x86/include/asm/shared/tdx.h
@@ -22,6 +22,7 @@
#define TDCS_NOTIFY_ENABLES 0x9100000000000010

/* TDX hypercall Leaf IDs */
+#define TDVMCALL_GET_TD_VM_CALL_INFO 0x10000
#define TDVMCALL_MAP_GPA 0x10001
#define TDVMCALL_GET_QUOTE 0x10002
#define TDVMCALL_REPORT_FATAL_ERROR 0x10003
diff --git a/arch/x86/kvm/vmx/tdx.c b/arch/x86/kvm/vmx/tdx.c
index b5aae9d784f7..413359741085 100644
--- a/arch/x86/kvm/vmx/tdx.c
+++ b/arch/x86/kvm/vmx/tdx.c
@@ -1528,6 +1528,20 @@ 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, TDVMCALL_STATUS_INVALID_OPERAND);
+ else {
+ tdvmcall_set_return_code(vcpu, TDVMCALL_STATUS_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))
@@ -1550,6 +1564,8 @@ static int handle_tdvmcall(struct kvm_vcpu *vcpu)
return tdx_emulate_rdmsr(vcpu);
case EXIT_REASON_MSR_WRITE:
return tdx_emulate_wrmsr(vcpu);
+ case TDVMCALL_GET_TD_VM_CALL_INFO:
+ return tdx_get_td_vm_call_info(vcpu);
default:
break;
}
--
2.46.0