On Wed, Aug 20, 2025 at 11:02:11PM +0100, Marc Zyngier wrote:
Mark Brown broonie@kernel.org wrote:
As per DDI 0487 RWTXBY we need to manage PSTATE.EXLOCK when entering an
Nit: please use an underscore between the type of a statement and its "name", as it makes it a bit more readable (R_WTXBY).
Updated as you request. I have seen both usages - the non _ version plays nicer with searching the PDF to find the rules since you can just copy it directly into a PDF viewer.
- // EL, or to GCSCR_ELx.EXLOCKEN for an exception to the same
- // exception level. See ARM DDI 0487 RWTXBY, D.1.3.2 in K.a.
- new |= enter_exception64_gcs(vcpu, mode, target_mode);
- new |= PSR_D_BIT; new |= PSR_A_BIT; new |= PSR_I_BIT;
But that's not the only case where we have to deal with EXLOCK, is it? What of ERET and its PAuth variants? R_TYTWB says:
<quote> If in AArch64 state, any of the following situations can cause an illegal exception return:
[...]
- If the Effective value of GCSCR_ELx.EXLOCKEN is 1 and PSTATE.EXLOCK is 0, the execution of an exception return instruction to return to the current Exception level ELx.
</quote>
My reading of the spec is that this needs handling.
Am I right in thinking that this handling is needed for the NV case only?