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caab277b | 1 | // SPDX-License-Identifier: GPL-2.0-only |
7de5c0af MZ |
2 | /* |
3 | * Copyright (C) 2016,2017 ARM Limited, All Rights Reserved. | |
4 | * Author: Marc Zyngier <marc.zyngier@arm.com> | |
7de5c0af MZ |
5 | */ |
6 | ||
7 | #include <linux/interrupt.h> | |
8 | #include <linux/irq.h> | |
9 | #include <linux/irqdomain.h> | |
10 | #include <linux/msi.h> | |
11 | #include <linux/sched.h> | |
12 | ||
13 | #include <linux/irqchip/arm-gic-v4.h> | |
14 | ||
7954907b MZ |
15 | /* |
16 | * WARNING: The blurb below assumes that you understand the | |
17 | * intricacies of GICv3, GICv4, and how a guest's view of a GICv3 gets | |
18 | * translated into GICv4 commands. So it effectively targets at most | |
19 | * two individuals. You know who you are. | |
20 | * | |
21 | * The core GICv4 code is designed to *avoid* exposing too much of the | |
22 | * core GIC code (that would in turn leak into the hypervisor code), | |
23 | * and instead provide a hypervisor agnostic interface to the HW (of | |
24 | * course, the astute reader will quickly realize that hypervisor | |
25 | * agnostic actually means KVM-specific - what were you thinking?). | |
26 | * | |
27 | * In order to achieve a modicum of isolation, we try to hide most of | |
28 | * the GICv4 "stuff" behind normal irqchip operations: | |
29 | * | |
30 | * - Any guest-visible VLPI is backed by a Linux interrupt (and a | |
31 | * physical LPI which gets unmapped when the guest maps the | |
32 | * VLPI). This allows the same DevID/EventID pair to be either | |
33 | * mapped to the LPI (host) or the VLPI (guest). Note that this is | |
34 | * exclusive, and you cannot have both. | |
35 | * | |
36 | * - Enabling/disabling a VLPI is done by issuing mask/unmask calls. | |
37 | * | |
38 | * - Guest INT/CLEAR commands are implemented through | |
39 | * irq_set_irqchip_state(). | |
40 | * | |
41 | * - The *bizarre* stuff (mapping/unmapping an interrupt to a VLPI, or | |
42 | * issuing an INV after changing a priority) gets shoved into the | |
43 | * irq_set_vcpu_affinity() method. While this is quite horrible | |
44 | * (let's face it, this is the irqchip version of an ioctl), it | |
45 | * confines the crap to a single location. And map/unmap really is | |
46 | * about setting the affinity of a VLPI to a vcpu, so only INV is | |
47 | * majorly out of place. So there. | |
48 | * | |
49 | * A number of commands are simply not provided by this interface, as | |
50 | * they do not make direct sense. For example, MAPD is purely local to | |
51 | * the virtual ITS (because it references a virtual device, and the | |
52 | * physical ITS is still very much in charge of the physical | |
53 | * device). Same goes for things like MAPC (the physical ITS deals | |
54 | * with the actual vPE affinity, and not the braindead concept of | |
55 | * collection). SYNC is not provided either, as each and every command | |
56 | * is followed by a VSYNC. This could be relaxed in the future, should | |
57 | * this be seen as a bottleneck (yes, this means *never*). | |
58 | * | |
59 | * But handling VLPIs is only one side of the job of the GICv4 | |
60 | * code. The other (darker) side is to take care of the doorbell | |
61 | * interrupts which are delivered when a VLPI targeting a non-running | |
62 | * vcpu is being made pending. | |
63 | * | |
64 | * The choice made here is that each vcpu (VPE in old northern GICv4 | |
65 | * dialect) gets a single doorbell LPI, no matter how many interrupts | |
66 | * are targeting it. This has a nice property, which is that the | |
67 | * interrupt becomes a handle for the VPE, and that the hypervisor | |
68 | * code can manipulate it through the normal interrupt API: | |
69 | * | |
70 | * - VMs (or rather the VM abstraction that matters to the GIC) | |
71 | * contain an irq domain where each interrupt maps to a VPE. In | |
72 | * turn, this domain sits on top of the normal LPI allocator, and a | |
73 | * specially crafted irq_chip implementation. | |
74 | * | |
75 | * - mask/unmask do what is expected on the doorbell interrupt. | |
76 | * | |
77 | * - irq_set_affinity is used to move a VPE from one redistributor to | |
78 | * another. | |
79 | * | |
80 | * - irq_set_vcpu_affinity once again gets hijacked for the purpose of | |
81 | * creating a new sub-API, namely scheduling/descheduling a VPE | |
82 | * (which involves programming GICR_V{PROP,PEND}BASER) and | |
83 | * performing INVALL operations. | |
84 | */ | |
85 | ||
7de5c0af MZ |
86 | static struct irq_domain *gic_domain; |
87 | static const struct irq_domain_ops *vpe_domain_ops; | |
166cba71 | 88 | static const struct irq_domain_ops *sgi_domain_ops; |
7de5c0af MZ |
89 | |
90 | int its_alloc_vcpu_irqs(struct its_vm *vm) | |
91 | { | |
92 | int vpe_base_irq, i; | |
93 | ||
94 | vm->fwnode = irq_domain_alloc_named_id_fwnode("GICv4-vpe", | |
95 | task_pid_nr(current)); | |
96 | if (!vm->fwnode) | |
97 | goto err; | |
98 | ||
99 | vm->domain = irq_domain_create_hierarchy(gic_domain, 0, vm->nr_vpes, | |
100 | vm->fwnode, vpe_domain_ops, | |
101 | vm); | |
102 | if (!vm->domain) | |
103 | goto err; | |
104 | ||
105 | for (i = 0; i < vm->nr_vpes; i++) { | |
106 | vm->vpes[i]->its_vm = vm; | |
107 | vm->vpes[i]->idai = true; | |
108 | } | |
109 | ||
110 | vpe_base_irq = __irq_domain_alloc_irqs(vm->domain, -1, vm->nr_vpes, | |
111 | NUMA_NO_NODE, vm, | |
112 | false, NULL); | |
113 | if (vpe_base_irq <= 0) | |
114 | goto err; | |
115 | ||
116 | for (i = 0; i < vm->nr_vpes; i++) | |
117 | vm->vpes[i]->irq = vpe_base_irq + i; | |
118 | ||
119 | return 0; | |
120 | ||
121 | err: | |
122 | if (vm->domain) | |
123 | irq_domain_remove(vm->domain); | |
124 | if (vm->fwnode) | |
125 | irq_domain_free_fwnode(vm->fwnode); | |
126 | ||
127 | return -ENOMEM; | |
128 | } | |
129 | ||
130 | void its_free_vcpu_irqs(struct its_vm *vm) | |
131 | { | |
132 | irq_domain_free_irqs(vm->vpes[0]->irq, vm->nr_vpes); | |
133 | irq_domain_remove(vm->domain); | |
134 | irq_domain_free_fwnode(vm->fwnode); | |
135 | } | |
eab84318 MZ |
136 | |
137 | static int its_send_vpe_cmd(struct its_vpe *vpe, struct its_cmd_info *info) | |
138 | { | |
139 | return irq_set_vcpu_affinity(vpe->irq, info); | |
140 | } | |
141 | ||
142 | int its_schedule_vpe(struct its_vpe *vpe, bool on) | |
143 | { | |
144 | struct its_cmd_info info; | |
8e01d9a3 | 145 | int ret; |
eab84318 MZ |
146 | |
147 | WARN_ON(preemptible()); | |
148 | ||
149 | info.cmd_type = on ? SCHEDULE_VPE : DESCHEDULE_VPE; | |
150 | ||
8e01d9a3 MZ |
151 | ret = its_send_vpe_cmd(vpe, &info); |
152 | if (!ret) | |
153 | vpe->resident = on; | |
154 | ||
155 | return ret; | |
eab84318 MZ |
156 | } |
157 | ||
158 | int its_invall_vpe(struct its_vpe *vpe) | |
159 | { | |
160 | struct its_cmd_info info = { | |
161 | .cmd_type = INVALL_VPE, | |
162 | }; | |
163 | ||
164 | return its_send_vpe_cmd(vpe, &info); | |
165 | } | |
f2eac75d MZ |
166 | |
167 | int its_map_vlpi(int irq, struct its_vlpi_map *map) | |
168 | { | |
169 | struct its_cmd_info info = { | |
170 | .cmd_type = MAP_VLPI, | |
6c09ffd0 AB |
171 | { |
172 | .map = map, | |
173 | }, | |
f2eac75d | 174 | }; |
90dc7122 | 175 | int ret; |
f2eac75d MZ |
176 | |
177 | /* | |
178 | * The host will never see that interrupt firing again, so it | |
179 | * is vital that we don't do any lazy masking. | |
180 | */ | |
181 | irq_set_status_flags(irq, IRQ_DISABLE_UNLAZY); | |
182 | ||
90dc7122 MZ |
183 | ret = irq_set_vcpu_affinity(irq, &info); |
184 | if (ret) | |
185 | irq_clear_status_flags(irq, IRQ_DISABLE_UNLAZY); | |
186 | ||
187 | return ret; | |
f2eac75d MZ |
188 | } |
189 | ||
190 | int its_get_vlpi(int irq, struct its_vlpi_map *map) | |
191 | { | |
192 | struct its_cmd_info info = { | |
193 | .cmd_type = GET_VLPI, | |
6c09ffd0 AB |
194 | { |
195 | .map = map, | |
196 | }, | |
f2eac75d MZ |
197 | }; |
198 | ||
199 | return irq_set_vcpu_affinity(irq, &info); | |
200 | } | |
201 | ||
202 | int its_unmap_vlpi(int irq) | |
203 | { | |
204 | irq_clear_status_flags(irq, IRQ_DISABLE_UNLAZY); | |
205 | return irq_set_vcpu_affinity(irq, NULL); | |
206 | } | |
207 | ||
208 | int its_prop_update_vlpi(int irq, u8 config, bool inv) | |
209 | { | |
210 | struct its_cmd_info info = { | |
211 | .cmd_type = inv ? PROP_UPDATE_AND_INV_VLPI : PROP_UPDATE_VLPI, | |
6c09ffd0 AB |
212 | { |
213 | .config = config, | |
214 | }, | |
f2eac75d MZ |
215 | }; |
216 | ||
217 | return irq_set_vcpu_affinity(irq, &info); | |
218 | } | |
3d63cb53 | 219 | |
166cba71 MZ |
220 | int its_init_v4(struct irq_domain *domain, |
221 | const struct irq_domain_ops *vpe_ops, | |
222 | const struct irq_domain_ops *sgi_ops) | |
3d63cb53 MZ |
223 | { |
224 | if (domain) { | |
225 | pr_info("ITS: Enabling GICv4 support\n"); | |
226 | gic_domain = domain; | |
166cba71 MZ |
227 | vpe_domain_ops = vpe_ops; |
228 | sgi_domain_ops = sgi_ops; | |
3d63cb53 MZ |
229 | return 0; |
230 | } | |
231 | ||
232 | pr_err("ITS: No GICv4 VPE domain allocated\n"); | |
233 | return -ENODEV; | |
234 | } |