1/* SPDX-License-Identifier: GPL-2.0 */
 2#ifndef _ASM_X86_INTEL_RDT_SCHED_H
 3#define _ASM_X86_INTEL_RDT_SCHED_H
 4
 5#ifdef CONFIG_INTEL_RDT
 6
 7#include <linux/sched.h>
 8#include <linux/jump_label.h>
 9
10#define IA32_PQR_ASSOC	0x0c8f
11
12/**
13 * struct intel_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 intel_pqr_state {
28	u32			cur_rmid;
29	u32			cur_closid;
30	u32			default_rmid;
31	u32			default_closid;
32};
33
34DECLARE_PER_CPU(struct intel_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 * __intel_rdt_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 __intel_rdt_sched_in(void)
55{
56	struct intel_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 intel_rdt_sched_in(void)
82{
83	if (static_branch_likely(&rdt_enable_key))
84		__intel_rdt_sched_in();
85}
86
87#else
88
89static inline void intel_rdt_sched_in(void) {}
90
91#endif /* CONFIG_INTEL_RDT */
92
93#endif /* _ASM_X86_INTEL_RDT_SCHED_H */