[PATCH v1 32/40] i386/tdx: Disable PIC for TDX VMs

Xiaoyao Li
2022-08-02T07:50:57Z

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>
Acked-by: Gerd Hoffmann <kraxel@redhat.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 70c56b7ba32c..2f317a6bb55b 100644
--- a/target/i386/kvm/tdx.c
+++ b/target/i386/kvm/tdx.c
@@ -668,6 +668,13 @@ 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