KVM: x86/xen: Bug the VM if 32-bit KVM observes a 64-bit mode hypercall

Bug the VM if 32-bit KVM attempts to handle a 64-bit hypercall, primarily
so that a future change to set "input" in mode-specific code doesn't
trigger a false positive warn=>error:

  arch/x86/kvm/xen.c:1687:6: error: variable 'input' is used uninitialized
                                    whenever 'if' condition is false [-Werror,-Wsometimes-uninitialized]
   1687 |         if (!longmode) {
        |             ^~~~~~~~~
  arch/x86/kvm/xen.c:1708:31: note: uninitialized use occurs here
   1708 |         trace_kvm_xen_hypercall(cpl, input, params[0], params[1], params[2],
        |                                      ^~~~~
  x86/kvm/xen.c:1687:2: note: remove the 'if' if its condition is always true
   1687 |         if (!longmode) {
        |         ^~~~~~~~~~~~~~
  arch/x86/kvm/xen.c:1677:11: note: initialize the variable 'input' to silence this warning
   1677 |         u64 input, params[6], r = -ENOSYS;
        |                  ^
  1 error generated.

Note, params[] also has the same flaw, but -Wsometimes-uninitialized
doesn't seem to be enforced for arrays, presumably because it's difficult
to avoid false positives on specific entries.

Reviewed-by: Binbin Wu <binbin.wu@linux.intel.com>
Link: https://patch.msgid.link/20260529222223.870923-3-seanjc@google.com
Signed-off-by: Sean Christopherson <seanjc@google.com>

0 files changed, 0 insertions, 0 deletions