On Mon, Aug 19, 2024 at 04:44:52PM +0100, Mark Brown wrote: > On Mon, Aug 19, 2024 at 12:46:13PM +0100, Catalin Marinas wrote: > > On Thu, Aug 01, 2024 at 01:06:46PM +0100, Mark Brown wrote:
> > > + /* > > > + * Ensure that GCS changes are observable by/from other PEs in > > > + * case of migration. > > > + */ > > > + if (task_gcs_el0_enabled(current) || task_gcs_el0_enabled(next)) > > > + gcsb_dsync(); > > Could we do the sysreg writing under this 'if' block? If no app is using > > GCS (which would be the case for a while), it looks like unnecessary > > sysreg accesses. > Yes, that should be fine I think. I forgot when writing the above that we always allow reads from GCSPR_EL0 in order to avoid corner cases for unwinders in the case of asynchronous disable. I'd expect that to be cheap to access though.
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