[v7,38/52] i386/apic: Skip kvm_apic_put() for TDX

Commit Message

Xiaoyao Li Jan. 24, 2025, 1:20 p.m. UTC

KVM neithers allow writing to MSR_IA32_APICBASE for TDs, nor allow for
KVM_SET_LAPIC[*].

Note, KVM_GET_LAPIC is also disallowed for TDX. It is called in the path

  do_kvm_cpu_synchronize_state()
  -> kvm_arch_get_registers()
     -> kvm_get_apic()

and it's already disllowed for confidential guest through
guest_state_protected.

[*] https://lore.kernel.org/all/[e-mail]/

Signed-off-by: Xiaoyao Li <[e-mail]>
---
 hw/i386/kvm/apic.c | 5 +++++
 1 file changed, 5 insertions(+)

Patch

diff --git a/hw/i386/kvm/apic.c b/hw/i386/kvm/apic.c
index 757510600098..a1850524a67f 100644
--- a/hw/i386/kvm/apic.c
+++ b/hw/i386/kvm/apic.c
@@ -17,6 +17,7 @@ 
 #include "system/hw_accel.h"
 #include "system/kvm.h"
 #include "kvm/kvm_i386.h"
+#include "kvm/tdx.h"
 
 static inline void kvm_apic_set_reg(struct kvm_lapic_state *kapic,
                                     int reg_id, uint32_t val)
@@ -141,6 +142,10 @@  static void kvm_apic_put(CPUState *cs, run_on_cpu_data data)
     struct kvm_lapic_state kapic;
     int ret;
 
+    if(is_tdx_vm()) {
+        return;
+    }
+
     kvm_put_apicbase(s->cpu, s->apicbase);
     kvm_put_apic_state(s, &kapic);