1 /* SPDX-License-Identifier: GPL-2.0 */ 2 /* Copyright (C) 2025 Arm Ltd. */ 3 4 #ifndef __ASM__MPAM_H 5 #define __ASM__MPAM_H 6 7 #include <linux/arm_mpam.h> 8 #include <linux/bitfield.h> 9 #include <linux/jump_label.h> 10 #include <linux/percpu.h> 11 #include <linux/sched.h> 12 13 #include <asm/sysreg.h> 14 15 DECLARE_STATIC_KEY_FALSE(mpam_enabled); 16 DECLARE_PER_CPU(u64, arm64_mpam_default); 17 DECLARE_PER_CPU(u64, arm64_mpam_current); 18 19 /* 20 * The value of the MPAM0_EL1 sysreg when a task is in resctrl's default group. 21 * This is used by the context switch code to use the resctrl CPU property 22 * instead. The value is modified when CDP is enabled/disabled by mounting 23 * the resctrl filesystem. 24 */ 25 extern u64 arm64_mpam_global_default; 26 27 #ifdef CONFIG_ARM64_MPAM 28 static inline u64 __mpam_regval(u16 partid_d, u16 partid_i, u8 pmg_d, u8 pmg_i) 29 { 30 return FIELD_PREP(MPAM0_EL1_PARTID_D, partid_d) | 31 FIELD_PREP(MPAM0_EL1_PARTID_I, partid_i) | 32 FIELD_PREP(MPAM0_EL1_PMG_D, pmg_d) | 33 FIELD_PREP(MPAM0_EL1_PMG_I, pmg_i); 34 } 35 36 static inline void mpam_set_cpu_defaults(int cpu, u16 partid_d, u16 partid_i, 37 u8 pmg_d, u8 pmg_i) 38 { 39 u64 default_val = __mpam_regval(partid_d, partid_i, pmg_d, pmg_i); 40 41 WRITE_ONCE(per_cpu(arm64_mpam_default, cpu), default_val); 42 } 43 44 /* 45 * The resctrl filesystem writes to the partid/pmg values for threads and CPUs, 46 * which may race with reads in mpam_thread_switch(). Ensure only one of the old 47 * or new values are used. Particular care should be taken with the pmg field as 48 * mpam_thread_switch() may read a partid and pmg that don't match, causing this 49 * value to be stored with cache allocations, despite being considered 'free' by 50 * resctrl. 51 */ 52 static inline u64 mpam_get_regval(struct task_struct *tsk) 53 { 54 return READ_ONCE(task_thread_info(tsk)->mpam_partid_pmg); 55 } 56 57 static inline void mpam_set_task_partid_pmg(struct task_struct *tsk, 58 u16 partid_d, u16 partid_i, 59 u8 pmg_d, u8 pmg_i) 60 { 61 u64 regval = __mpam_regval(partid_d, partid_i, pmg_d, pmg_i); 62 63 WRITE_ONCE(task_thread_info(tsk)->mpam_partid_pmg, regval); 64 } 65 66 static inline void mpam_thread_switch(struct task_struct *tsk) 67 { 68 u64 oldregval; 69 int cpu = smp_processor_id(); 70 u64 regval = mpam_get_regval(tsk); 71 72 if (!static_branch_likely(&mpam_enabled)) 73 return; 74 75 if (regval == READ_ONCE(arm64_mpam_global_default)) 76 regval = READ_ONCE(per_cpu(arm64_mpam_default, cpu)); 77 78 oldregval = READ_ONCE(per_cpu(arm64_mpam_current, cpu)); 79 if (oldregval == regval) 80 return; 81 82 write_sysreg_s(regval | MPAM1_EL1_MPAMEN, SYS_MPAM1_EL1); 83 if (system_supports_sme()) 84 write_sysreg_s(regval & (MPAMSM_EL1_PARTID_D | MPAMSM_EL1_PMG_D), SYS_MPAMSM_EL1); 85 isb(); 86 87 /* Synchronising the EL0 write is left until the ERET to EL0 */ 88 write_sysreg_s(regval, SYS_MPAM0_EL1); 89 90 WRITE_ONCE(per_cpu(arm64_mpam_current, cpu), regval); 91 } 92 #else 93 static inline void mpam_thread_switch(struct task_struct *tsk) {} 94 #endif /* CONFIG_ARM64_MPAM */ 95 96 #endif /* __ASM__MPAM_H */ 97