From: James Morse <james.morse@arm.com> maillist inclusion category: feature bugzilla: https://gitee.com/openeuler/kernel/issues/IC30P1 Reference: https://git.kernel.org/pub/scm/linux/kernel/git/morse/linux.git/commit/?h=mp... -------------------------------- The MPAM system registers will be lost if the CPU is reset during PSCI's CPU_SUSPEND. 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. Signed-off-by: James Morse <james.morse@arm.com> Signed-off-by: Zeng Heng <zengheng4@huawei.com> --- arch/arm64/kernel/mpam.c | 28 ++++++++++++++++++++++++++++ 1 file changed, 28 insertions(+) diff --git a/arch/arm64/kernel/mpam.c b/arch/arm64/kernel/mpam.c index d8891d5c59c0..d3ac3bfb5564 100644 --- a/arch/arm64/kernel/mpam.c +++ b/arch/arm64/kernel/mpam.c @@ -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> #include <linux/crash_dump.h> @@ -13,6 +14,32 @@ DEFINE_STATIC_KEY_FALSE(mpam_enabled); DEFINE_PER_CPU(u64, arm64_mpam_default); DEFINE_PER_CPU(u64, arm64_mpam_current); +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(0, SYS_MPAM1_EL1); + 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) { u16 partid_max; @@ -29,6 +56,7 @@ static int __init arm64_mpam_register_cpus(void) partid_max = FIELD_GET(MPAMIDR_PARTID_MAX, mpamidr); pmg_max = FIELD_GET(MPAMIDR_PMG_MAX, mpamidr); + cpu_pm_register_notifier(&mpam_pm_nb); return mpam_register_requestor(partid_max, pmg_max); } arch_initcall(arm64_mpam_register_cpus); -- 2.25.1