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arm64: mpam: Add cpu_pm notifier to restore MPAM sysregs

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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: Gavin Shan <gshan@redhat.com>
Tested-by: Shaopeng Tan <tan.shaopeng@jp.fujitsu.com>
Tested-by: Peter Newman <peternewman@google.com>
Tested-by: Zeng Heng <zengheng4@huawei.com>
Tested-by: Punit Agrawal <punit.agrawal@oss.qualcomm.com>
Tested-by: Jesse Chick <jessechick@os.amperecomputing.com>
Reviewed-by: Zeng Heng <zengheng4@huawei.com>
Reviewed-by: Shaopeng Tan <tan.shaopeng@jp.fujitsu.com>
Reviewed-by: Jonathan Cameron <jonathan.cameron@huawei.com>
Reviewed-by: Gavin Shan <gshan@redhat.com>
Reviewed-by: Catalin Marinas <catalin.marinas@arm.com>
Co-developed-by: Ben Horgan <ben.horgan@arm.com>
Signed-off-by: Ben Horgan <ben.horgan@arm.com>
Signed-off-by: James Morse <james.morse@arm.com>
This commit is contained in:
James Morse 2026-03-13 14:45:47 +00:00
parent 831a7f1672
commit 735dad9999
1 changed files with 33 additions and 0 deletions
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33
arch/arm64/kernel/mpam.c
View File

@ -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() */