arch/x86/include/asm/resctrl_sched.h

   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  */
  27 struct resctrl_pqr_state {
  28         u32                     cur_rmid;
  29         u32                     cur_closid;
  30         u32                     default_rmid;
  31         u32                     default_closid;
  32 };
  33
  34 DECLARE_PER_CPU(struct resctrl_pqr_state, pqr_state);
  35
  36 DECLARE_STATIC_KEY_FALSE(rdt_enable_key);
  37 DECLARE_STATIC_KEY_FALSE(rdt_alloc_enable_key);
  38 DECLARE_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  */
  54 static 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
  81 static inline void resctrl_sched_in(void)
  82 {
  83         if (static_branch_likely(&rdt_enable_key))
  84                 __resctrl_sched_in();
  85 }
  86
  87 #else
  88
  89 static inline void resctrl_sched_in(void) {}
  90
  91 #endif /* CONFIG_X86_CPU_RESCTRL */
  92
  93 #endif /* _ASM_X86_RESCTRL_SCHED_H */