1 /* SPDX-License-Identifier: GPL-2.0 */
2 #ifndef _ASM_X86_RESCTRL_H
3 #define _ASM_X86_RESCTRL_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  */
__resctrl_sched_in(void)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 	u32 tmp;
60 
61 	/*
62 	 * If this task has a closid/rmid assigned, use it.
63 	 * Else use the closid/rmid assigned to this cpu.
64 	 */
65 	if (static_branch_likely(&rdt_alloc_enable_key)) {
66 		tmp = READ_ONCE(current->closid);
67 		if (tmp)
68 			closid = tmp;
69 	}
70 
71 	if (static_branch_likely(&rdt_mon_enable_key)) {
72 		tmp = READ_ONCE(current->rmid);
73 		if (tmp)
74 			rmid = tmp;
75 	}
76 
77 	if (closid != state->cur_closid || rmid != state->cur_rmid) {
78 		state->cur_closid = closid;
79 		state->cur_rmid = rmid;
80 		wrmsr(IA32_PQR_ASSOC, rmid, closid);
81 	}
82 }
83 
resctrl_sched_in(void)84 static inline void resctrl_sched_in(void)
85 {
86 	if (static_branch_likely(&rdt_enable_key))
87 		__resctrl_sched_in();
88 }
89 
90 void resctrl_cpu_detect(struct cpuinfo_x86 *c);
91 
92 #else
93 
resctrl_sched_in(void)94 static inline void resctrl_sched_in(void) {}
resctrl_cpu_detect(struct cpuinfo_x86 * c)95 static inline void resctrl_cpu_detect(struct cpuinfo_x86 *c) {}
96 
97 #endif /* CONFIG_X86_CPU_RESCTRL */
98 
99 #endif /* _ASM_X86_RESCTRL_H */
100