[PATCH 2/3] KVM: VMX: Disallowing using to_vmx() in common VT code

[Sean Christopherson <seanjc@google.com>]

Poison to_vmx() in main.c and posted_intr.c so that attempting to interpret
the vCPU as a VMX vCPU will fail at compile time, as opposed to failing at
runtime, or worse corrupting state without outright failing.

Note, to_tdx() is buried in tdx.c, i.e. isn't broadly reachable, and so
doesn't need the same treatment as to_vmx().

Signed-off-by: Sean Christopherson <seanjc@google.com>
---
 arch/x86/kvm/vmx/main.c        | 2 ++
 arch/x86/kvm/vmx/posted_intr.c | 2 ++
 2 files changed, 4 insertions(+)

diff --git a/arch/x86/kvm/vmx/main.c b/arch/x86/kvm/vmx/main.c
index aa5b44bb212b..95d89d809c19 100644
--- a/arch/x86/kvm/vmx/main.c
+++ b/arch/x86/kvm/vmx/main.c
@@ -11,6 +11,8 @@
 #include "tdx.h"
 #include "tdx_arch.h"
 
+#pragma GCC poison to_vmx
+
 #ifdef CONFIG_KVM_INTEL_TDX
 static_assert(offsetof(struct vcpu_vmx, vt) == offsetof(struct vcpu_tdx, vt));
 
diff --git a/arch/x86/kvm/vmx/posted_intr.c b/arch/x86/kvm/vmx/posted_intr.c
index 4a6d9a17da23..24221ba553be 100644
--- a/arch/x86/kvm/vmx/posted_intr.c
+++ b/arch/x86/kvm/vmx/posted_intr.c
@@ -14,6 +14,8 @@
 #include "vmx.h"
 #include "tdx.h"
 
+#pragma GCC poison to_vmx
+
 /*
  * Maintain a per-CPU list of vCPUs that need to be awakened by wakeup_handler()
  * when a WAKEUP_VECTOR interrupted is posted.  vCPUs are added to the list when
-- 
2.55.0.691.gc56d675ccc-goog