1 // SPDX-License-Identifier: GPL-2.0-only
2 /*
3  * Copyright (C) 2016,2017 ARM Limited, All Rights Reserved.
4  * Author: Marc Zyngier <marc.zyngier@arm.com>
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 
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 
86 static struct irq_domain *gic_domain;
87 static const struct irq_domain_ops *vpe_domain_ops;
88 static const struct irq_domain_ops *sgi_domain_ops;
89 
90 #ifdef CONFIG_ARM64
91 #include <asm/cpufeature.h>
92 
gic_cpuif_has_vsgi(void)93 bool gic_cpuif_has_vsgi(void)
94 {
95 	unsigned long fld, reg = read_sanitised_ftr_reg(SYS_ID_AA64PFR0_EL1);
96 
97 	fld = cpuid_feature_extract_unsigned_field(reg, ID_AA64PFR0_EL1_GIC_SHIFT);
98 
99 	return fld >= 0x3;
100 }
101 #else
gic_cpuif_has_vsgi(void)102 bool gic_cpuif_has_vsgi(void)
103 {
104 	return false;
105 }
106 #endif
107 
has_v4_1(void)108 static bool has_v4_1(void)
109 {
110 	return !!sgi_domain_ops;
111 }
112 
has_v4_1_sgi(void)113 static bool has_v4_1_sgi(void)
114 {
115 	return has_v4_1() && gic_cpuif_has_vsgi();
116 }
117 
its_alloc_vcpu_sgis(struct its_vpe * vpe,int idx)118 static int its_alloc_vcpu_sgis(struct its_vpe *vpe, int idx)
119 {
120 	char *name;
121 	int sgi_base;
122 
123 	if (!has_v4_1_sgi())
124 		return 0;
125 
126 	name = kasprintf(GFP_KERNEL, "GICv4-sgi-%d", task_pid_nr(current));
127 	if (!name)
128 		goto err;
129 
130 	vpe->fwnode = irq_domain_alloc_named_id_fwnode(name, idx);
131 	if (!vpe->fwnode)
132 		goto err;
133 
134 	kfree(name);
135 	name = NULL;
136 
137 	vpe->sgi_domain = irq_domain_create_linear(vpe->fwnode, 16,
138 						   sgi_domain_ops, vpe);
139 	if (!vpe->sgi_domain)
140 		goto err;
141 
142 	sgi_base = irq_domain_alloc_irqs(vpe->sgi_domain, 16, NUMA_NO_NODE, vpe);
143 	if (sgi_base <= 0)
144 		goto err;
145 
146 	return 0;
147 
148 err:
149 	if (vpe->sgi_domain)
150 		irq_domain_remove(vpe->sgi_domain);
151 	if (vpe->fwnode)
152 		irq_domain_free_fwnode(vpe->fwnode);
153 	kfree(name);
154 	return -ENOMEM;
155 }
156 
its_alloc_vcpu_irqs(struct its_vm * vm)157 int its_alloc_vcpu_irqs(struct its_vm *vm)
158 {
159 	int vpe_base_irq, i;
160 
161 	vm->fwnode = irq_domain_alloc_named_id_fwnode("GICv4-vpe",
162 						      task_pid_nr(current));
163 	if (!vm->fwnode)
164 		goto err;
165 
166 	vm->domain = irq_domain_create_hierarchy(gic_domain, 0, vm->nr_vpes,
167 						 vm->fwnode, vpe_domain_ops,
168 						 vm);
169 	if (!vm->domain)
170 		goto err;
171 
172 	for (i = 0; i < vm->nr_vpes; i++) {
173 		vm->vpes[i]->its_vm = vm;
174 		vm->vpes[i]->idai = true;
175 	}
176 
177 	vpe_base_irq = irq_domain_alloc_irqs(vm->domain, vm->nr_vpes,
178 					     NUMA_NO_NODE, vm);
179 	if (vpe_base_irq <= 0)
180 		goto err;
181 
182 	for (i = 0; i < vm->nr_vpes; i++) {
183 		int ret;
184 		vm->vpes[i]->irq = vpe_base_irq + i;
185 		ret = its_alloc_vcpu_sgis(vm->vpes[i], i);
186 		if (ret)
187 			goto err;
188 	}
189 
190 	return 0;
191 
192 err:
193 	if (vm->domain)
194 		irq_domain_remove(vm->domain);
195 	if (vm->fwnode)
196 		irq_domain_free_fwnode(vm->fwnode);
197 
198 	return -ENOMEM;
199 }
200 
its_free_sgi_irqs(struct its_vm * vm)201 static void its_free_sgi_irqs(struct its_vm *vm)
202 {
203 	int i;
204 
205 	if (!has_v4_1_sgi())
206 		return;
207 
208 	for (i = 0; i < vm->nr_vpes; i++) {
209 		unsigned int irq = irq_find_mapping(vm->vpes[i]->sgi_domain, 0);
210 
211 		if (WARN_ON(!irq))
212 			continue;
213 
214 		irq_domain_free_irqs(irq, 16);
215 		irq_domain_remove(vm->vpes[i]->sgi_domain);
216 		irq_domain_free_fwnode(vm->vpes[i]->fwnode);
217 	}
218 }
219 
its_free_vcpu_irqs(struct its_vm * vm)220 void its_free_vcpu_irqs(struct its_vm *vm)
221 {
222 	its_free_sgi_irqs(vm);
223 	irq_domain_free_irqs(vm->vpes[0]->irq, vm->nr_vpes);
224 	irq_domain_remove(vm->domain);
225 	irq_domain_free_fwnode(vm->fwnode);
226 }
227 
its_send_vpe_cmd(struct its_vpe * vpe,struct its_cmd_info * info)228 static int its_send_vpe_cmd(struct its_vpe *vpe, struct its_cmd_info *info)
229 {
230 	return irq_set_vcpu_affinity(vpe->irq, info);
231 }
232 
its_make_vpe_non_resident(struct its_vpe * vpe,bool db)233 int its_make_vpe_non_resident(struct its_vpe *vpe, bool db)
234 {
235 	struct irq_desc *desc = irq_to_desc(vpe->irq);
236 	struct its_cmd_info info = { };
237 	int ret;
238 
239 	WARN_ON(preemptible());
240 
241 	info.cmd_type = DESCHEDULE_VPE;
242 	if (has_v4_1()) {
243 		/* GICv4.1 can directly deal with doorbells */
244 		info.req_db = db;
245 	} else {
246 		/* Undo the nested disable_irq() calls... */
247 		while (db && irqd_irq_disabled(&desc->irq_data))
248 			enable_irq(vpe->irq);
249 	}
250 
251 	ret = its_send_vpe_cmd(vpe, &info);
252 	if (!ret)
253 		vpe->resident = false;
254 
255 	vpe->ready = false;
256 
257 	return ret;
258 }
259 
its_make_vpe_resident(struct its_vpe * vpe,bool g0en,bool g1en)260 int its_make_vpe_resident(struct its_vpe *vpe, bool g0en, bool g1en)
261 {
262 	struct its_cmd_info info = { };
263 	int ret;
264 
265 	WARN_ON(preemptible());
266 
267 	info.cmd_type = SCHEDULE_VPE;
268 	if (has_v4_1()) {
269 		info.g0en = g0en;
270 		info.g1en = g1en;
271 	} else {
272 		/* Disabled the doorbell, as we're about to enter the guest */
273 		disable_irq_nosync(vpe->irq);
274 	}
275 
276 	ret = its_send_vpe_cmd(vpe, &info);
277 	if (!ret)
278 		vpe->resident = true;
279 
280 	return ret;
281 }
282 
its_commit_vpe(struct its_vpe * vpe)283 int its_commit_vpe(struct its_vpe *vpe)
284 {
285 	struct its_cmd_info info = {
286 		.cmd_type = COMMIT_VPE,
287 	};
288 	int ret;
289 
290 	WARN_ON(preemptible());
291 
292 	ret = its_send_vpe_cmd(vpe, &info);
293 	if (!ret)
294 		vpe->ready = true;
295 
296 	return ret;
297 }
298 
299 
its_invall_vpe(struct its_vpe * vpe)300 int its_invall_vpe(struct its_vpe *vpe)
301 {
302 	struct its_cmd_info info = {
303 		.cmd_type = INVALL_VPE,
304 	};
305 
306 	return its_send_vpe_cmd(vpe, &info);
307 }
308 
its_map_vlpi(int irq,struct its_vlpi_map * map)309 int its_map_vlpi(int irq, struct its_vlpi_map *map)
310 {
311 	struct its_cmd_info info = {
312 		.cmd_type = MAP_VLPI,
313 		{
314 			.map      = map,
315 		},
316 	};
317 	int ret;
318 
319 	/*
320 	 * The host will never see that interrupt firing again, so it
321 	 * is vital that we don't do any lazy masking.
322 	 */
323 	irq_set_status_flags(irq, IRQ_DISABLE_UNLAZY);
324 
325 	ret = irq_set_vcpu_affinity(irq, &info);
326 	if (ret)
327 		irq_clear_status_flags(irq, IRQ_DISABLE_UNLAZY);
328 
329 	return ret;
330 }
331 
its_get_vlpi(int irq,struct its_vlpi_map * map)332 int its_get_vlpi(int irq, struct its_vlpi_map *map)
333 {
334 	struct its_cmd_info info = {
335 		.cmd_type = GET_VLPI,
336 		{
337 			.map      = map,
338 		},
339 	};
340 
341 	return irq_set_vcpu_affinity(irq, &info);
342 }
343 
its_unmap_vlpi(int irq)344 int its_unmap_vlpi(int irq)
345 {
346 	irq_clear_status_flags(irq, IRQ_DISABLE_UNLAZY);
347 	return irq_set_vcpu_affinity(irq, NULL);
348 }
349 
its_prop_update_vlpi(int irq,u8 config,bool inv)350 int its_prop_update_vlpi(int irq, u8 config, bool inv)
351 {
352 	struct its_cmd_info info = {
353 		.cmd_type = inv ? PROP_UPDATE_AND_INV_VLPI : PROP_UPDATE_VLPI,
354 		{
355 			.config   = config,
356 		},
357 	};
358 
359 	return irq_set_vcpu_affinity(irq, &info);
360 }
361 
its_prop_update_vsgi(int irq,u8 priority,bool group)362 int its_prop_update_vsgi(int irq, u8 priority, bool group)
363 {
364 	struct its_cmd_info info = {
365 		.cmd_type = PROP_UPDATE_VSGI,
366 		{
367 			.priority	= priority,
368 			.group		= group,
369 		},
370 	};
371 
372 	return irq_set_vcpu_affinity(irq, &info);
373 }
374 
its_init_v4(struct irq_domain * domain,const struct irq_domain_ops * vpe_ops,const struct irq_domain_ops * sgi_ops)375 int its_init_v4(struct irq_domain *domain,
376 		const struct irq_domain_ops *vpe_ops,
377 		const struct irq_domain_ops *sgi_ops)
378 {
379 	if (domain) {
380 		pr_info("ITS: Enabling GICv4 support\n");
381 		gic_domain = domain;
382 		vpe_domain_ops = vpe_ops;
383 		sgi_domain_ops = sgi_ops;
384 		return 0;
385 	}
386 
387 	pr_err("ITS: No GICv4 VPE domain allocated\n");
388 	return -ENODEV;
389 }
390