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Diffstat (limited to '')
| -rw-r--r-- | arch/x86/include/asm/resctrl.h | 99 |
1 files changed, 99 insertions, 0 deletions
diff --git a/arch/x86/include/asm/resctrl.h b/arch/x86/include/asm/resctrl.h new file mode 100644 index 000000000..b9ccdf5ea --- /dev/null +++ b/arch/x86/include/asm/resctrl.h @@ -0,0 +1,99 @@ +/* SPDX-License-Identifier: GPL-2.0 */ +#ifndef _ASM_X86_RESCTRL_H +#define _ASM_X86_RESCTRL_H + +#ifdef CONFIG_X86_CPU_RESCTRL + +#include <linux/sched.h> +#include <linux/jump_label.h> + +#define IA32_PQR_ASSOC 0x0c8f + +/** + * struct resctrl_pqr_state - State cache for the PQR MSR + * @cur_rmid: The cached Resource Monitoring ID + * @cur_closid: The cached Class Of Service ID + * @default_rmid: The user assigned Resource Monitoring ID + * @default_closid: The user assigned cached Class Of Service ID + * + * The upper 32 bits of IA32_PQR_ASSOC contain closid and the + * lower 10 bits rmid. The update to IA32_PQR_ASSOC always + * contains both parts, so we need to cache them. This also + * stores the user configured per cpu CLOSID and RMID. + * + * The cache also helps to avoid pointless updates if the value does + * not change. + */ +struct resctrl_pqr_state { + u32 cur_rmid; + u32 cur_closid; + u32 default_rmid; + u32 default_closid; +}; + +DECLARE_PER_CPU(struct resctrl_pqr_state, pqr_state); + +DECLARE_STATIC_KEY_FALSE(rdt_enable_key); +DECLARE_STATIC_KEY_FALSE(rdt_alloc_enable_key); +DECLARE_STATIC_KEY_FALSE(rdt_mon_enable_key); + +/* + * __resctrl_sched_in() - Writes the task's CLOSid/RMID to IA32_PQR_MSR + * + * Following considerations are made so that this has minimal impact + * on scheduler hot path: + * - This will stay as no-op unless we are running on an Intel SKU + * which supports resource control or monitoring and we enable by + * mounting the resctrl file system. + * - Caches the per cpu CLOSid/RMID values and does the MSR write only + * when a task with a different CLOSid/RMID is scheduled in. + * - We allocate RMIDs/CLOSids globally in order to keep this as + * simple as possible. + * Must be called with preemption disabled. + */ +static inline void __resctrl_sched_in(struct task_struct *tsk) +{ + struct resctrl_pqr_state *state = this_cpu_ptr(&pqr_state); + u32 closid = state->default_closid; + u32 rmid = state->default_rmid; + u32 tmp; + + /* + * If this task has a closid/rmid assigned, use it. + * Else use the closid/rmid assigned to this cpu. + */ + if (static_branch_likely(&rdt_alloc_enable_key)) { + tmp = READ_ONCE(tsk->closid); + if (tmp) + closid = tmp; + } + + if (static_branch_likely(&rdt_mon_enable_key)) { + tmp = READ_ONCE(tsk->rmid); + if (tmp) + rmid = tmp; + } + + if (closid != state->cur_closid || rmid != state->cur_rmid) { + state->cur_closid = closid; + state->cur_rmid = rmid; + wrmsr(IA32_PQR_ASSOC, rmid, closid); + } +} + +static inline void resctrl_sched_in(struct task_struct *tsk) +{ + if (static_branch_likely(&rdt_enable_key)) + __resctrl_sched_in(tsk); +} + +void resctrl_cpu_detect(struct cpuinfo_x86 *c); + +#else + +static inline void resctrl_sched_in(struct task_struct *tsk) {} +static inline void resctrl_cpu_detect(struct cpuinfo_x86 *c) {} + +#endif /* CONFIG_X86_CPU_RESCTRL */ + +#endif /* _ASM_X86_RESCTRL_H */ |