[RFC PATCH 07/23] i386/kvm: Squash getting/putting guest state for TDX VMs

[Isaku Yamahata]

From: Sean Christopherson <sean.j.christopherson@intel.com>

Ignore get/put state of TDX VMs as accessing/mutating guest state of
producation TDs is not supported.
Allow kvm_arch_get_registers() to run as normal, except for MSRs, for
debug TDs, and silently ignores attempts to read guest state for
non-debug TDs.

Signed-off-by: Sean Christopherson <sean.j.christopherson@intel.com>
---
 target/i386/kvm/kvm.c | 18 +++++++++++++++---
 1 file changed, 15 insertions(+), 3 deletions(-)

diff --git a/target/i386/kvm/kvm.c b/target/i386/kvm/kvm.c
index ab7a896bd2..9c5f669b7c 100644
--- a/target/i386/kvm/kvm.c
+++ b/target/i386/kvm/kvm.c
@@ -2565,6 +2565,11 @@ void kvm_put_apicbase(X86CPU *cpu, uint64_t value)
 {
     int ret;
 
+    /* TODO: Allow accessing guest state for debug TDs. */
+    if (vm_type == KVM_X86_TDX_VM) {
+            return;
+    }
+
     ret = kvm_put_one_msr(cpu, MSR_IA32_APICBASE, value);
     assert(ret == 1);
 }
@@ -4019,6 +4024,11 @@ int kvm_arch_put_registers(CPUState *cpu, int level)
 
     assert(cpu_is_stopped(cpu) || qemu_cpu_is_self(cpu));
 
+    /* TODO: Allow accessing guest state for debug TDs. */
+    if (vm_type == KVM_X86_TDX_VM) {
+        return 0;
+    }
+
     /* must be before kvm_put_nested_state so that EFER.SVME is set */
     ret = kvm_put_sregs(x86_cpu);
     if (ret < 0) {
@@ -4129,9 +4139,11 @@ int kvm_arch_get_registers(CPUState *cs)
     if (ret < 0) {
         goto out;
     }
-    ret = kvm_get_msrs(cpu);
-    if (ret < 0) {
-        goto out;
+    if (vm_type != KVM_X86_TDX_VM) {
+        ret = kvm_get_msrs(cpu);
+        if (ret < 0) {
+            goto out;
+        }
     }
     ret = kvm_get_apic(cpu);
     if (ret < 0) {
-- 
2.17.1