Commit 735dad99 authored by James Morse's avatar James Morse
Browse files

arm64: mpam: Add cpu_pm notifier to restore MPAM sysregs 



The MPAM system registers will be lost if the CPU is reset during PSCI's
CPU_SUSPEND.

Add a PM notifier to restore them.

mpam_thread_switch(current) can't be used as this won't make any changes if
the in-memory copy says the register already has the correct value. In
reality the system register is UNKNOWN out of reset.

Tested-by: default avatarGavin Shan <gshan@redhat.com>
Tested-by: default avatarShaopeng Tan <tan.shaopeng@jp.fujitsu.com>
Tested-by: default avatarPeter Newman <peternewman@google.com>
Tested-by: default avatarZeng Heng <zengheng4@huawei.com>
Tested-by: default avatarPunit Agrawal <punit.agrawal@oss.qualcomm.com>
Tested-by: default avatarJesse Chick <jessechick@os.amperecomputing.com>
Reviewed-by: default avatarZeng Heng <zengheng4@huawei.com>
Reviewed-by: default avatarShaopeng Tan <tan.shaopeng@jp.fujitsu.com>
Reviewed-by: default avatarJonathan Cameron <jonathan.cameron@huawei.com>
Reviewed-by: default avatarGavin Shan <gshan@redhat.com>
Reviewed-by: default avatarCatalin Marinas <catalin.marinas@arm.com>
Co-developed-by: default avatarBen Horgan <ben.horgan@arm.com>
Signed-off-by: default avatarBen Horgan <ben.horgan@arm.com>
Signed-off-by: default avatarJames Morse <james.morse@arm.com>
parent 831a7f16

arch/arm64/kernel/mpam.c

+33 −0
Original line number Diff line number Diff line
@@ -4,6 +4,7 @@ 
#include <asm/mpam.h>



#include <linux/arm_mpam.h>

#include <linux/cpu_pm.h>

#include <linux/jump_label.h>

#include <linux/percpu.h>
@@ -13,12 +14,44 @@ DEFINE_PER_CPU(u64, arm64_mpam_current); 


u64 arm64_mpam_global_default;



static int mpam_pm_notifier(struct notifier_block *self,

			    unsigned long cmd, void *v)

{

	u64 regval;

	int cpu = smp_processor_id();



	switch (cmd) {

	case CPU_PM_EXIT:

		/*

		 * Don't use mpam_thread_switch() as the system register

		 * value has changed under our feet.

		 */

		regval = READ_ONCE(per_cpu(arm64_mpam_current, cpu));

		write_sysreg_s(regval | MPAM1_EL1_MPAMEN, SYS_MPAM1_EL1);

		isb();



		write_sysreg_s(regval, SYS_MPAM0_EL1);



		return NOTIFY_OK;

	default:

		return NOTIFY_DONE;

	}

}



static struct notifier_block mpam_pm_nb = {

	.notifier_call = mpam_pm_notifier,

};



static int __init arm64_mpam_register_cpus(void)

{

	u64 mpamidr = read_sanitised_ftr_reg(SYS_MPAMIDR_EL1);

	u16 partid_max = FIELD_GET(MPAMIDR_EL1_PARTID_MAX, mpamidr);

	u8 pmg_max = FIELD_GET(MPAMIDR_EL1_PMG_MAX, mpamidr);



	if (!system_supports_mpam())

		return 0;



	cpu_pm_register_notifier(&mpam_pm_nb);

	return mpam_register_requestor(partid_max, pmg_max);

}

/* Must occur before mpam_msc_driver_init() from subsys_initcall() */