1 // SPDX-License-Identifier: GPL-2.0
2 /*
3  * Copyright 2019 Arm Limited
4  * Author: Andrew Murray <Andrew.Murray@arm.com>
5  */
6 #include <linux/kvm_host.h>
7 #include <linux/perf_event.h>
8 #include <asm/kvm_hyp.h>
9 
10 /*
11  * Given the perf event attributes and system type, determine
12  * if we are going to need to switch counters at guest entry/exit.
13  */
kvm_pmu_switch_needed(struct perf_event_attr * attr)14 static bool kvm_pmu_switch_needed(struct perf_event_attr *attr)
15 {
16 	/**
17 	 * With VHE the guest kernel runs at EL1 and the host at EL2,
18 	 * where user (EL0) is excluded then we have no reason to switch
19 	 * counters.
20 	 */
21 	if (has_vhe() && attr->exclude_user)
22 		return false;
23 
24 	/* Only switch if attributes are different */
25 	return (attr->exclude_host != attr->exclude_guest);
26 }
27 
28 /*
29  * Add events to track that we may want to switch at guest entry/exit
30  * time.
31  */
kvm_set_pmu_events(u32 set,struct perf_event_attr * attr)32 void kvm_set_pmu_events(u32 set, struct perf_event_attr *attr)
33 {
34 	struct kvm_host_data *ctx = this_cpu_ptr_hyp_sym(kvm_host_data);
35 
36 	if (!kvm_arm_support_pmu_v3() || !ctx || !kvm_pmu_switch_needed(attr))
37 		return;
38 
39 	if (!attr->exclude_host)
40 		ctx->pmu_events.events_host |= set;
41 	if (!attr->exclude_guest)
42 		ctx->pmu_events.events_guest |= set;
43 }
44 
45 /*
46  * Stop tracking events
47  */
kvm_clr_pmu_events(u32 clr)48 void kvm_clr_pmu_events(u32 clr)
49 {
50 	struct kvm_host_data *ctx = this_cpu_ptr_hyp_sym(kvm_host_data);
51 
52 	if (!kvm_arm_support_pmu_v3() || !ctx)
53 		return;
54 
55 	ctx->pmu_events.events_host &= ~clr;
56 	ctx->pmu_events.events_guest &= ~clr;
57 }
58 
59 #define PMEVTYPER_READ_CASE(idx)				\
60 	case idx:						\
61 		return read_sysreg(pmevtyper##idx##_el0)
62 
63 #define PMEVTYPER_WRITE_CASE(idx)				\
64 	case idx:						\
65 		write_sysreg(val, pmevtyper##idx##_el0);	\
66 		break
67 
68 #define PMEVTYPER_CASES(readwrite)				\
69 	PMEVTYPER_##readwrite##_CASE(0);			\
70 	PMEVTYPER_##readwrite##_CASE(1);			\
71 	PMEVTYPER_##readwrite##_CASE(2);			\
72 	PMEVTYPER_##readwrite##_CASE(3);			\
73 	PMEVTYPER_##readwrite##_CASE(4);			\
74 	PMEVTYPER_##readwrite##_CASE(5);			\
75 	PMEVTYPER_##readwrite##_CASE(6);			\
76 	PMEVTYPER_##readwrite##_CASE(7);			\
77 	PMEVTYPER_##readwrite##_CASE(8);			\
78 	PMEVTYPER_##readwrite##_CASE(9);			\
79 	PMEVTYPER_##readwrite##_CASE(10);			\
80 	PMEVTYPER_##readwrite##_CASE(11);			\
81 	PMEVTYPER_##readwrite##_CASE(12);			\
82 	PMEVTYPER_##readwrite##_CASE(13);			\
83 	PMEVTYPER_##readwrite##_CASE(14);			\
84 	PMEVTYPER_##readwrite##_CASE(15);			\
85 	PMEVTYPER_##readwrite##_CASE(16);			\
86 	PMEVTYPER_##readwrite##_CASE(17);			\
87 	PMEVTYPER_##readwrite##_CASE(18);			\
88 	PMEVTYPER_##readwrite##_CASE(19);			\
89 	PMEVTYPER_##readwrite##_CASE(20);			\
90 	PMEVTYPER_##readwrite##_CASE(21);			\
91 	PMEVTYPER_##readwrite##_CASE(22);			\
92 	PMEVTYPER_##readwrite##_CASE(23);			\
93 	PMEVTYPER_##readwrite##_CASE(24);			\
94 	PMEVTYPER_##readwrite##_CASE(25);			\
95 	PMEVTYPER_##readwrite##_CASE(26);			\
96 	PMEVTYPER_##readwrite##_CASE(27);			\
97 	PMEVTYPER_##readwrite##_CASE(28);			\
98 	PMEVTYPER_##readwrite##_CASE(29);			\
99 	PMEVTYPER_##readwrite##_CASE(30)
100 
101 /*
102  * Read a value direct from PMEVTYPER<idx> where idx is 0-30
103  * or PMCCFILTR_EL0 where idx is ARMV8_PMU_CYCLE_IDX (31).
104  */
kvm_vcpu_pmu_read_evtype_direct(int idx)105 static u64 kvm_vcpu_pmu_read_evtype_direct(int idx)
106 {
107 	switch (idx) {
108 	PMEVTYPER_CASES(READ);
109 	case ARMV8_PMU_CYCLE_IDX:
110 		return read_sysreg(pmccfiltr_el0);
111 	default:
112 		WARN_ON(1);
113 	}
114 
115 	return 0;
116 }
117 
118 /*
119  * Write a value direct to PMEVTYPER<idx> where idx is 0-30
120  * or PMCCFILTR_EL0 where idx is ARMV8_PMU_CYCLE_IDX (31).
121  */
kvm_vcpu_pmu_write_evtype_direct(int idx,u32 val)122 static void kvm_vcpu_pmu_write_evtype_direct(int idx, u32 val)
123 {
124 	switch (idx) {
125 	PMEVTYPER_CASES(WRITE);
126 	case ARMV8_PMU_CYCLE_IDX:
127 		write_sysreg(val, pmccfiltr_el0);
128 		break;
129 	default:
130 		WARN_ON(1);
131 	}
132 }
133 
134 /*
135  * Modify ARMv8 PMU events to include EL0 counting
136  */
kvm_vcpu_pmu_enable_el0(unsigned long events)137 static void kvm_vcpu_pmu_enable_el0(unsigned long events)
138 {
139 	u64 typer;
140 	u32 counter;
141 
142 	for_each_set_bit(counter, &events, 32) {
143 		typer = kvm_vcpu_pmu_read_evtype_direct(counter);
144 		typer &= ~ARMV8_PMU_EXCLUDE_EL0;
145 		kvm_vcpu_pmu_write_evtype_direct(counter, typer);
146 	}
147 }
148 
149 /*
150  * Modify ARMv8 PMU events to exclude EL0 counting
151  */
kvm_vcpu_pmu_disable_el0(unsigned long events)152 static void kvm_vcpu_pmu_disable_el0(unsigned long events)
153 {
154 	u64 typer;
155 	u32 counter;
156 
157 	for_each_set_bit(counter, &events, 32) {
158 		typer = kvm_vcpu_pmu_read_evtype_direct(counter);
159 		typer |= ARMV8_PMU_EXCLUDE_EL0;
160 		kvm_vcpu_pmu_write_evtype_direct(counter, typer);
161 	}
162 }
163 
164 /*
165  * On VHE ensure that only guest events have EL0 counting enabled.
166  * This is called from both vcpu_{load,put} and the sysreg handling.
167  * Since the latter is preemptible, special care must be taken to
168  * disable preemption.
169  */
kvm_vcpu_pmu_restore_guest(struct kvm_vcpu * vcpu)170 void kvm_vcpu_pmu_restore_guest(struct kvm_vcpu *vcpu)
171 {
172 	struct kvm_host_data *host;
173 	u32 events_guest, events_host;
174 
175 	if (!kvm_arm_support_pmu_v3() || !has_vhe())
176 		return;
177 
178 	preempt_disable();
179 	host = this_cpu_ptr_hyp_sym(kvm_host_data);
180 	events_guest = host->pmu_events.events_guest;
181 	events_host = host->pmu_events.events_host;
182 
183 	kvm_vcpu_pmu_enable_el0(events_guest);
184 	kvm_vcpu_pmu_disable_el0(events_host);
185 	preempt_enable();
186 }
187 
188 /*
189  * On VHE ensure that only host events have EL0 counting enabled
190  */
kvm_vcpu_pmu_restore_host(struct kvm_vcpu * vcpu)191 void kvm_vcpu_pmu_restore_host(struct kvm_vcpu *vcpu)
192 {
193 	struct kvm_host_data *host;
194 	u32 events_guest, events_host;
195 
196 	if (!kvm_arm_support_pmu_v3() || !has_vhe())
197 		return;
198 
199 	host = this_cpu_ptr_hyp_sym(kvm_host_data);
200 	events_guest = host->pmu_events.events_guest;
201 	events_host = host->pmu_events.events_host;
202 
203 	kvm_vcpu_pmu_enable_el0(events_host);
204 	kvm_vcpu_pmu_disable_el0(events_guest);
205 }
206