KVM: TDX: Check if there is valid exit infos based on vp_enter_ret

Check if there is valid exit info based on vp_enter_ret instead of relying
on the clobbered Exit Reason, in tdx_get_exit_info().

Current KVM uses "Exit Reason is not equal to the synthesized invalid
Exit Reason, -1u," as the condition to identify there is a real TD Exit
and valid exit infos.  However, there is one issue with this approach:
KVM updates the Exit Reason to the synthesized invalid Exit Reason for
real EPT MISCONFIG as well.  This is a false positive for real EPT
MISCONFIG, which has valid exit infos.

Though the issue can be addressed by changing the handling for real EPT
MISCONFIG to not update the Exit Reason to the synthesized one, relying
on the clobbered Exit Reason itself is brittle.  Instead, check
vp_enter_ret directly to identify if it is a valid Exit Reason.

Fixes: da407fe45908 ("KVM: TDX: Handle EPT violation/misconfig exit")
Cc: stable@vger.kernel.org
Suggested-by: Sean Christopherson <seanjc@google.com>
Signed-off-by: Xiaoyao Li <xiaoyao.li@intel.com>
Reviewed-by: Binbin Wu <binbin.wu@linux.intel.com>
Link: https://patch.msgid.link/20260819094903.3060020-3-xiaoyao.li@intel.com
Signed-off-by: Sean Christopherson <seanjc@google.com>

0 files changed, 0 insertions, 0 deletions