Re: [PATCH v20 05/14] KVM: arm64: Set PSTATE.EXLOCK when entering an exception

[Leonardo Bras]

On Tue, Sep 01, 2026 at 10:47:03PM +0100, Mark Brown wrote:
[...]
> +	/* When taking an exception to a higher EL EXLOCK is cleared. */
> +	if ((mode | PSR_MODE_THREAD_BIT) != target_mode)
> +		return 0;

"Higher" is mentioned here, but the comparison is a "!=", so I suppose 
here we trust the fact that we always have "mode <= target_mode", and only 
2 possible target exception levels (EL2h and EL1h).

It's a nit, but maybe a "<" here would be more clear?

The rest of the code seems correct based on R_WTXBY.

[...]
>  
> +	// PSTATE.EXLOCK is set to 0 upon any exception to a higher
> +	// EL, or to GCSCR_ELx.EXLOCKEN for an exception to the same
> +	// exception level.  See ARM DDI 0487 R_WTXBY.
> +	new |= compute_exlock(vcpu, mode, target_mode);

Same nit: am I really setting one bit here? or could be 
more stuff depending on the parameters? Having an "if (cond) new |= bit"
seems more clear to what is being done, without needing to read the comment 
above.

In any case, FWIW:

Reviewed-by: Leonardo Bras <leo.bras@xxxxxxx>

Thanks!
Leo