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 */