On Thu, 21 Aug 2025 21:44:21 +0100, Mark Brown broonie@kernel.org wrote:
On Wed, Aug 20, 2025 at 11:02:11PM +0100, Marc Zyngier wrote:
Mark Brown broonie@kernel.org wrote:
- // 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.
nit: I think you can drop the section number in the ARM ARM. The rule "numbers" are stable across revision of the document, and K.a is already absolutely ancient (over a year old and two revisions behind).
- 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?
So far, NV is indeed the only case where we have to emulate ERET.
M.