KVM: TDX: Don't assume exit_reason[31:16] is all-0 in tdx_to_vmx_exit_reason()

When handling the real Exit Reason, don't assume the upper 16 bits as
all-0 in tdx_to_vmx_exit_reason(), in preparation for enabling Bus Lock
VM exit.

When Bus Lock VM exit is enabled, the bit 26 of Exit Reason becomes
valid and it can be 1 with various exit reasons.  Change the logic in
tdx_to_vmx_exit_reason() to check the 'basic' Exit Reason for correctness.
Also preserve bit[31:16] when changing the (basic) Exit Reason, to not
lose the information in bit[31:16].

Change the return type of tdx_to_vmx_exit_reason() to
"union vmx_exit_reason" for the convenience of manipulating the basic
field.

Fixes: c42856af8f70 ("KVM: TDX: Add a place holder for handler of TDX hypercalls (TDG.VP.VMCALL)")
Cc: stable@vger.kernel.org
Signed-off-by: Xiaoyao Li <xiaoyao.li@intel.com>
Link: https://patch.msgid.link/20260819094903.3060020-5-xiaoyao.li@intel.com
Signed-off-by: Sean Christopherson <seanjc@google.com>

0 files changed, 0 insertions, 0 deletions