tjh.dev / kernel
Linux kernel mirror (for testing) git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
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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: 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>

James Morse 735dad99 831a7f16

+33
+33
arch/arm64/kernel/mpam.c
··· 4 4 #include <asm/mpam.h> 5 5 6 6 #include <linux/arm_mpam.h> 7 + #include <linux/cpu_pm.h> 7 8 #include <linux/jump_label.h> 8 9 #include <linux/percpu.h> 9 10 ··· 14 13 15 14 u64 arm64_mpam_global_default; 16 15 16 + static int mpam_pm_notifier(struct notifier_block *self, 17 + unsigned long cmd, void *v) 18 + { 19 + u64 regval; 20 + int cpu = smp_processor_id(); 21 + 22 + switch (cmd) { 23 + case CPU_PM_EXIT: 24 + /* 25 + * Don't use mpam_thread_switch() as the system register 26 + * value has changed under our feet. 27 + */ 28 + regval = READ_ONCE(per_cpu(arm64_mpam_current, cpu)); 29 + write_sysreg_s(regval | MPAM1_EL1_MPAMEN, SYS_MPAM1_EL1); 30 + isb(); 31 + 32 + write_sysreg_s(regval, SYS_MPAM0_EL1); 33 + 34 + return NOTIFY_OK; 35 + default: 36 + return NOTIFY_DONE; 37 + } 38 + } 39 + 40 + static struct notifier_block mpam_pm_nb = { 41 + .notifier_call = mpam_pm_notifier, 42 + }; 43 + 17 44 static int __init arm64_mpam_register_cpus(void) 18 45 { 19 46 u64 mpamidr = read_sanitised_ftr_reg(SYS_MPAMIDR_EL1); 20 47 u16 partid_max = FIELD_GET(MPAMIDR_EL1_PARTID_MAX, mpamidr); 21 48 u8 pmg_max = FIELD_GET(MPAMIDR_EL1_PMG_MAX, mpamidr); 22 49 50 + if (!system_supports_mpam()) 51 + return 0; 52 + 53 + cpu_pm_register_notifier(&mpam_pm_nb); 23 54 return mpam_register_requestor(partid_max, pmg_max); 24 55 } 25 56 /* Must occur before mpam_msc_driver_init() from subsys_initcall() */