Re: [PATCH v10 01/30] arm64/sysreg: Update SMIDR_EL1 to DDI0601 2025-06

[Mark Brown <broonie@kernel.org>]

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On Mon, May 11, 2026 at 11:40:02AM +0100, Mark Rutland wrote:
> On Sat, May 09, 2026 at 09:43:11AM +0900, Mark Brown wrote:

> > We're exposing the affinity fields so there's a build time issue.

> What I'm asking is what is the rationale for updating these definitions?
> e.g.

> * Are we planning to use any of the fields in a specific way in the
>   *host*?

> * Are we planning to use any of the fields in a specific way in the
>   *guest*?

> * Is this updated just out of habit?

> Knowing the rationale would help with review, even if that rationale is
> just "it seemed nice to use the latest".

The immediate motivation for including this in the current series is the
above.

> Which people are aware?

Probably a conversation best taken off list.

> > > Do we expect to expose that to VMs, or just hide priorities entirely? I
> > > suspect we probably want to require that the guest sees
> > > SMIDR_EL1.SMPS==0, and not care about any of that.

> > Currently we're not exposing priority support to guests so we don't need
> > to worry about it yet.

> Do we plan to in future?

The plan to evaluate the priority support that hardware implements in
the context of practical systems and consider if and how to expose it
for either hosts or guests, we need to ensure we've got a good
understanding of the system impacts and user needs.  Architecturally the
priority support is all very implementation defined.

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