[RFC PATCH v4 28/36] i386/tdx: Disable PIC for TDX VMs

[Xiaoyao Li]

Legacy PIC (8259) cannot be supported for TDX VMs since TDX module
doesn't allow directly interrupt injection.  Using posted interrupts
for the PIC is not a viable option as the guest BIOS/kernel will not
do EOI for PIC IRQs, i.e. will leave the vIRR bit set.

Hence disable PIC for TDX VMs and error out if user wants PIC.

Signed-off-by: Xiaoyao Li <xiaoyao.li@intel.com>
---
 target/i386/kvm/tdx.c | 7 +++++++
 1 file changed, 7 insertions(+)

diff --git a/target/i386/kvm/tdx.c b/target/i386/kvm/tdx.c
index 7ff4c6a9a7ca..59c7aa8f1818 100644
--- a/target/i386/kvm/tdx.c
+++ b/target/i386/kvm/tdx.c
@@ -333,6 +333,13 @@ int tdx_kvm_init(MachineState *ms, Error **errp)
         return -EINVAL;
     }
 
+    if (x86ms->pic == ON_OFF_AUTO_AUTO) {
+        x86ms->pic = ON_OFF_AUTO_OFF;
+    } else if (x86ms->pic == ON_OFF_AUTO_ON) {
+        error_setg(errp, "TDX VM doesn't support PIC");
+        return -EINVAL;
+    }
+
     if (!tdx_caps) {
         get_tdx_capabilities();
     }
-- 
2.27.0