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       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                 :     296002 : static inline void resctrl_sched_in(void) {}
      90                 :            : 
      91                 :            : #endif /* CONFIG_X86_CPU_RESCTRL */
      92                 :            : 
      93                 :            : #endif /* _ASM_X86_RESCTRL_SCHED_H */