On Mon, Nov 12, 2018 at 11:57:06AM +0000, Julien Thierry wrote: > diff --git a/arch/arm64/kernel/smp.c b/arch/arm64/kernel/smp.c > index 8dc9dde..e495360 100644 > --- a/arch/arm64/kernel/smp.c > +++ b/arch/arm64/kernel/smp.c > @@ -35,6 +35,7 @@ > #include <linux/smp.h> > #include <linux/seq_file.h> > #include <linux/irq.h> > +#include <linux/irqchip/arm-gic-v3.h> > #include <linux/percpu.h> > #include <linux/clockchips.h> > #include <linux/completion.h> > @@ -175,6 +176,25 @@ int __cpu_up(unsigned int cpu, struct task_struct *idle) > return ret; > } > > +static void init_gic_priority_masking(void) > +{ > + u32 gic_sre = gic_read_sre(); > + u32 cpuflags; > + > + if (WARN_ON(!(gic_sre & ICC_SRE_EL1_SRE))) > + return; > + > + WARN_ON(!irqs_disabled()); > + > + gic_write_pmr(GIC_PRIO_IRQOFF); > + > + cpuflags = read_sysreg(daif); > + > + /* We can only unmask PSR.I if we can take aborts */ > + if (!(cpuflags & PSR_A_BIT)) > + write_sysreg(cpuflags & ~PSR_I_BIT, daif);
I don't understand this. If you don't switch off PSR_I_BIT here, where does it happen? In which scenario do we actually have the A bit still set? At a quick look, smp_prepare_boot_cpu() would have the A bit cleared previously by setup_arch(). We have secondary_start_kernel() where you call init_gic_priority_masking() before local_daif_restore(). So what happens if you always turn off PSR_I_BIT here? -- Catalin