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

[Mark Brown]

On Thu, Sep 03, 2026 at 03:25:09PM +0100, Leonardo Bras wrote:
> 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?

Sure.

> > +	// 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.

The goal with the comment is to explain the rule that the code is
implementing in a style similar to all the other field updates in the
same function.

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