LXR linux/arch/x86/include/asm/resctrl

   1/* SPDX-License-Identifier: GPL-2.0 */
   2#ifndef _ASM_X86_RESCTRL_SCHED_H
   3#define _ASM_X86_RESCTRL_SCHED_H
   4
   5#ifdef CONFIG_X86_CPU_RESCTRL
   6
   7#include <linux/sched.h>
   8#include <linux/jump_label.h>
   9
  10#define IA32_PQR_ASSOC  0x0c8f
  11
  12/**
  13 * struct resctrl_pqr_state - State cache for the PQR MSR
  14 * @cur_rmid:           The cached Resource Monitoring ID
  15 * @cur_closid: The cached Class Of Service ID
  16 * @default_rmid:       The user assigned Resource Monitoring ID
  17 * @default_closid:     The user assigned cached Class Of Service ID
  18 *
  19 * The upper 32 bits of IA32_PQR_ASSOC contain closid and the
  20 * lower 10 bits rmid. The update to IA32_PQR_ASSOC always
  21 * contains both parts, so we need to cache them. This also
  22 * stores the user configured per cpu CLOSID and RMID.
  23 *
  24 * The cache also helps to avoid pointless updates if the value does
  25 * not change.
  26 */
  27struct resctrl_pqr_state {
  28        u32                     cur_rmid;
  29        u32                     cur_closid;
  30        u32                     default_rmid;
  31        u32                     default_closid;
  32};
  33
  34DECLARE_PER_CPU(struct resctrl_pqr_state, pqr_state);
  35
  36DECLARE_STATIC_KEY_FALSE(rdt_enable_key);
  37DECLARE_STATIC_KEY_FALSE(rdt_alloc_enable_key);
  38DECLARE_STATIC_KEY_FALSE(rdt_mon_enable_key);
  39
  40/*
  41 * __resctrl_sched_in() - Writes the task's CLOSid/RMID to IA32_PQR_MSR
  42 *
  43 * Following considerations are made so that this has minimal impact
  44 * on scheduler hot path:
  45 * - This will stay as no-op unless we are running on an Intel SKU
  46 *   which supports resource control or monitoring and we enable by
  47 *   mounting the resctrl file system.
  48 * - Caches the per cpu CLOSid/RMID values and does the MSR write only
  49 *   when a task with a different CLOSid/RMID is scheduled in.
  50 * - We allocate RMIDs/CLOSids globally in order to keep this as
  51 *   simple as possible.
  52 * Must be called with preemption disabled.
  53 */
  54static void __resctrl_sched_in(void)
  55{
  56        struct resctrl_pqr_state *state = this_cpu_ptr(&pqr_state);
  57        u32 closid = state->default_closid;
  58        u32 rmid = state->default_rmid;
  59
  60        /*
  61         * If this task has a closid/rmid assigned, use it.
  62         * Else use the closid/rmid assigned to this cpu.
  63         */
  64        if (static_branch_likely(&rdt_alloc_enable_key)) {
  65                if (current->closid)
  66                        closid = current->closid;
  67        }
  68
  69        if (static_branch_likely(&rdt_mon_enable_key)) {
  70                if (current->rmid)
  71                        rmid = current->rmid;
  72        }
  73
  74        if (closid != state->cur_closid || rmid != state->cur_rmid) {
  75                state->cur_closid = closid;
  76                state->cur_rmid = rmid;
  77                wrmsr(IA32_PQR_ASSOC, rmid, closid);
  78        }
  79}
  80
  81static inline void resctrl_sched_in(void)
  82{
  83        if (static_branch_likely(&rdt_enable_key))
  84                __resctrl_sched_in();
  85}
  86
  87#else
  88
  89static inline void resctrl_sched_in(void) {}
  90
  91#endif /* CONFIG_X86_CPU_RESCTRL */
  92
  93#endif /* _ASM_X86_RESCTRL_SCHED_H */
  94