xref: /openbmc/linux/arch/arm64/kvm/pmu.c (revision 2a598d0b)
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 
9 static DEFINE_PER_CPU(struct kvm_pmu_events, kvm_pmu_events);
10 
11 /*
12  * Given the perf event attributes and system type, determine
13  * if we are going to need to switch counters at guest entry/exit.
14  */
15 static bool kvm_pmu_switch_needed(struct perf_event_attr *attr)
16 {
17 	/**
18 	 * With VHE the guest kernel runs at EL1 and the host at EL2,
19 	 * where user (EL0) is excluded then we have no reason to switch
20 	 * counters.
21 	 */
22 	if (has_vhe() && attr->exclude_user)
23 		return false;
24 
25 	/* Only switch if attributes are different */
26 	return (attr->exclude_host != attr->exclude_guest);
27 }
28 
29 struct kvm_pmu_events *kvm_get_pmu_events(void)
30 {
31 	return this_cpu_ptr(&kvm_pmu_events);
32 }
33 
34 /*
35  * Add events to track that we may want to switch at guest entry/exit
36  * time.
37  */
38 void kvm_set_pmu_events(u32 set, struct perf_event_attr *attr)
39 {
40 	struct kvm_pmu_events *pmu = kvm_get_pmu_events();
41 
42 	if (!kvm_arm_support_pmu_v3() || !pmu || !kvm_pmu_switch_needed(attr))
43 		return;
44 
45 	if (!attr->exclude_host)
46 		pmu->events_host |= set;
47 	if (!attr->exclude_guest)
48 		pmu->events_guest |= set;
49 }
50 
51 /*
52  * Stop tracking events
53  */
54 void kvm_clr_pmu_events(u32 clr)
55 {
56 	struct kvm_pmu_events *pmu = kvm_get_pmu_events();
57 
58 	if (!kvm_arm_support_pmu_v3() || !pmu)
59 		return;
60 
61 	pmu->events_host &= ~clr;
62 	pmu->events_guest &= ~clr;
63 }
64 
65 #define PMEVTYPER_READ_CASE(idx)				\
66 	case idx:						\
67 		return read_sysreg(pmevtyper##idx##_el0)
68 
69 #define PMEVTYPER_WRITE_CASE(idx)				\
70 	case idx:						\
71 		write_sysreg(val, pmevtyper##idx##_el0);	\
72 		break
73 
74 #define PMEVTYPER_CASES(readwrite)				\
75 	PMEVTYPER_##readwrite##_CASE(0);			\
76 	PMEVTYPER_##readwrite##_CASE(1);			\
77 	PMEVTYPER_##readwrite##_CASE(2);			\
78 	PMEVTYPER_##readwrite##_CASE(3);			\
79 	PMEVTYPER_##readwrite##_CASE(4);			\
80 	PMEVTYPER_##readwrite##_CASE(5);			\
81 	PMEVTYPER_##readwrite##_CASE(6);			\
82 	PMEVTYPER_##readwrite##_CASE(7);			\
83 	PMEVTYPER_##readwrite##_CASE(8);			\
84 	PMEVTYPER_##readwrite##_CASE(9);			\
85 	PMEVTYPER_##readwrite##_CASE(10);			\
86 	PMEVTYPER_##readwrite##_CASE(11);			\
87 	PMEVTYPER_##readwrite##_CASE(12);			\
88 	PMEVTYPER_##readwrite##_CASE(13);			\
89 	PMEVTYPER_##readwrite##_CASE(14);			\
90 	PMEVTYPER_##readwrite##_CASE(15);			\
91 	PMEVTYPER_##readwrite##_CASE(16);			\
92 	PMEVTYPER_##readwrite##_CASE(17);			\
93 	PMEVTYPER_##readwrite##_CASE(18);			\
94 	PMEVTYPER_##readwrite##_CASE(19);			\
95 	PMEVTYPER_##readwrite##_CASE(20);			\
96 	PMEVTYPER_##readwrite##_CASE(21);			\
97 	PMEVTYPER_##readwrite##_CASE(22);			\
98 	PMEVTYPER_##readwrite##_CASE(23);			\
99 	PMEVTYPER_##readwrite##_CASE(24);			\
100 	PMEVTYPER_##readwrite##_CASE(25);			\
101 	PMEVTYPER_##readwrite##_CASE(26);			\
102 	PMEVTYPER_##readwrite##_CASE(27);			\
103 	PMEVTYPER_##readwrite##_CASE(28);			\
104 	PMEVTYPER_##readwrite##_CASE(29);			\
105 	PMEVTYPER_##readwrite##_CASE(30)
106 
107 /*
108  * Read a value direct from PMEVTYPER<idx> where idx is 0-30
109  * or PMCCFILTR_EL0 where idx is ARMV8_PMU_CYCLE_IDX (31).
110  */
111 static u64 kvm_vcpu_pmu_read_evtype_direct(int idx)
112 {
113 	switch (idx) {
114 	PMEVTYPER_CASES(READ);
115 	case ARMV8_PMU_CYCLE_IDX:
116 		return read_sysreg(pmccfiltr_el0);
117 	default:
118 		WARN_ON(1);
119 	}
120 
121 	return 0;
122 }
123 
124 /*
125  * Write a value direct to PMEVTYPER<idx> where idx is 0-30
126  * or PMCCFILTR_EL0 where idx is ARMV8_PMU_CYCLE_IDX (31).
127  */
128 static void kvm_vcpu_pmu_write_evtype_direct(int idx, u32 val)
129 {
130 	switch (idx) {
131 	PMEVTYPER_CASES(WRITE);
132 	case ARMV8_PMU_CYCLE_IDX:
133 		write_sysreg(val, pmccfiltr_el0);
134 		break;
135 	default:
136 		WARN_ON(1);
137 	}
138 }
139 
140 /*
141  * Modify ARMv8 PMU events to include EL0 counting
142  */
143 static void kvm_vcpu_pmu_enable_el0(unsigned long events)
144 {
145 	u64 typer;
146 	u32 counter;
147 
148 	for_each_set_bit(counter, &events, 32) {
149 		typer = kvm_vcpu_pmu_read_evtype_direct(counter);
150 		typer &= ~ARMV8_PMU_EXCLUDE_EL0;
151 		kvm_vcpu_pmu_write_evtype_direct(counter, typer);
152 	}
153 }
154 
155 /*
156  * Modify ARMv8 PMU events to exclude EL0 counting
157  */
158 static void kvm_vcpu_pmu_disable_el0(unsigned long events)
159 {
160 	u64 typer;
161 	u32 counter;
162 
163 	for_each_set_bit(counter, &events, 32) {
164 		typer = kvm_vcpu_pmu_read_evtype_direct(counter);
165 		typer |= ARMV8_PMU_EXCLUDE_EL0;
166 		kvm_vcpu_pmu_write_evtype_direct(counter, typer);
167 	}
168 }
169 
170 /*
171  * On VHE ensure that only guest events have EL0 counting enabled.
172  * This is called from both vcpu_{load,put} and the sysreg handling.
173  * Since the latter is preemptible, special care must be taken to
174  * disable preemption.
175  */
176 void kvm_vcpu_pmu_restore_guest(struct kvm_vcpu *vcpu)
177 {
178 	struct kvm_pmu_events *pmu;
179 	u32 events_guest, events_host;
180 
181 	if (!kvm_arm_support_pmu_v3() || !has_vhe())
182 		return;
183 
184 	preempt_disable();
185 	pmu = kvm_get_pmu_events();
186 	events_guest = pmu->events_guest;
187 	events_host = pmu->events_host;
188 
189 	kvm_vcpu_pmu_enable_el0(events_guest);
190 	kvm_vcpu_pmu_disable_el0(events_host);
191 	preempt_enable();
192 }
193 
194 /*
195  * On VHE ensure that only host events have EL0 counting enabled
196  */
197 void kvm_vcpu_pmu_restore_host(struct kvm_vcpu *vcpu)
198 {
199 	struct kvm_pmu_events *pmu;
200 	u32 events_guest, events_host;
201 
202 	if (!kvm_arm_support_pmu_v3() || !has_vhe())
203 		return;
204 
205 	pmu = kvm_get_pmu_events();
206 	events_guest = pmu->events_guest;
207 	events_host = pmu->events_host;
208 
209 	kvm_vcpu_pmu_enable_el0(events_host);
210 	kvm_vcpu_pmu_disable_el0(events_guest);
211 }
212 
213 /*
214  * With VHE, keep track of the PMUSERENR_EL0 value for the host EL0 on the pCPU
215  * where PMUSERENR_EL0 for the guest is loaded, since PMUSERENR_EL0 is switched
216  * to the value for the guest on vcpu_load().  The value for the host EL0
217  * will be restored on vcpu_put(), before returning to userspace.
218  * This isn't necessary for nVHE, as the register is context switched for
219  * every guest enter/exit.
220  *
221  * Return true if KVM takes care of the register. Otherwise return false.
222  */
223 bool kvm_set_pmuserenr(u64 val)
224 {
225 	struct kvm_cpu_context *hctxt;
226 	struct kvm_vcpu *vcpu;
227 
228 	if (!kvm_arm_support_pmu_v3() || !has_vhe())
229 		return false;
230 
231 	vcpu = kvm_get_running_vcpu();
232 	if (!vcpu || !vcpu_get_flag(vcpu, PMUSERENR_ON_CPU))
233 		return false;
234 
235 	hctxt = &this_cpu_ptr(&kvm_host_data)->host_ctxt;
236 	ctxt_sys_reg(hctxt, PMUSERENR_EL0) = val;
237 	return true;
238 }
239