On Wed, Sep 27, 2023 at 03:01:08PM +0100, Joey Gouly wrote: > +static void permission_overlay_switch(struct task_struct *next) > +{ > + if (alternative_has_cap_unlikely(ARM64_HAS_S1POE)) { > + current->thread.por_el0 = read_sysreg_s(SYS_POR_EL0); > + write_sysreg_s(next->thread.por_el0, SYS_POR_EL0); > + } > +} Does this need an ISB or is the POR_EL0 register write self-synchronising? -- Catalin