Re: [PATCH v19 04/14] KVM: arm64: Ensure GCS memory effects are visible

On Wed, Aug 19, 2026 at 06:23:11PM +0100, Leonardo Bras wrote:

> You state that we do _not_ use GCS in the hypervisor, nor in the host.
> I understand that we GCSB() when we exit the vcpu context, but why would we 
> need to GCSB() before getting back in?

> If cpus will GCSB() on guest_exit, and host/hyp does not use GCS, there 
> should be no GCS pending operation at the entry point.

That's there to ensure that updates written by another PE are seen,
following the same pattern as DDI0487 M.c K10.6.5 example K10-8 (or the
prior migration between PEs example, that has barriers due to the stack
switch operations rather than as distinct instructions).

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