aboutsummaryrefslogtreecommitdiff
path: root/virt/kvm/arm/vgic/vgic-v4.c
blob: 4a37292855bc7f8bed299b99407d68882b98c84e (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
/*
 * Copyright (C) 2017 ARM Ltd.
 * Author: Marc Zyngier <marc.zyngier@arm.com>
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License version 2 as
 * published by the Free Software Foundation.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program.  If not, see <http://www.gnu.org/licenses/>.
 */

#include <linux/interrupt.h>
#include <linux/irq.h>
#include <linux/irqdomain.h>
#include <linux/kvm_host.h>
#include <linux/irqchip/arm-gic-v3.h>

#include "vgic.h"

/*
 * How KVM uses GICv4 (insert rude comments here):
 *
 * The vgic-v4 layer acts as a bridge between several entities:
 * - The GICv4 ITS representation offered by the ITS driver
 * - VFIO, which is in charge of the PCI endpoint
 * - The virtual ITS, which is the only thing the guest sees
 *
 * The configuration of VLPIs is triggered by a callback from VFIO,
 * instructing KVM that a PCI device has been configured to deliver
 * MSIs to a vITS.
 *
 * kvm_vgic_v4_set_forwarding() is thus called with the routing entry,
 * and this is used to find the corresponding vITS data structures
 * (ITS instance, device, event and irq) using a process that is
 * extremely similar to the injection of an MSI.
 *
 * At this stage, we can link the guest's view of an LPI (uniquely
 * identified by the routing entry) and the host irq, using the GICv4
 * driver mapping operation. Should the mapping succeed, we've then
 * successfully upgraded the guest's LPI to a VLPI. We can then start
 * with updating GICv4's view of the property table and generating an
 * INValidation in order to kickstart the delivery of this VLPI to the
 * guest directly, without software intervention. Well, almost.
 *
 * When the PCI endpoint is deconfigured, this operation is reversed
 * with VFIO calling kvm_vgic_v4_unset_forwarding().
 *
 * Once the VLPI has been mapped, it needs to follow any change the
 * guest performs on its LPI through the vITS. For that, a number of
 * command handlers have hooks to communicate these changes to the HW:
 * - Any invalidation triggers a call to its_prop_update_vlpi()
 * - The INT command results in a irq_set_irqchip_state(), which
 *   generates an INT on the corresponding VLPI.
 * - The CLEAR command results in a irq_set_irqchip_state(), which
 *   generates an CLEAR on the corresponding VLPI.
 * - DISCARD translates into an unmap, similar to a call to
 *   kvm_vgic_v4_unset_forwarding().
 * - MOVI is translated by an update of the existing mapping, changing
 *   the target vcpu, resulting in a VMOVI being generated.
 * - MOVALL is translated by a string of mapping updates (similar to
 *   the handling of MOVI). MOVALL is horrible.
 *
 * Note that a DISCARD/MAPTI sequence emitted from the guest without
 * reprogramming the PCI endpoint after MAPTI does not result in a
 * VLPI being mapped, as there is no callback from VFIO (the guest
 * will get the interrupt via the normal SW injection). Fixing this is
 * not trivial, and requires some horrible messing with the VFIO
 * internals. Not fun. Don't do that.
 *
 * Then there is the scheduling. Each time a vcpu is about to run on a
 * physical CPU, KVM must tell the corresponding redistributor about
 * it. And if we've migrated our vcpu from one CPU to another, we must
 * tell the ITS (so that the messages reach the right redistributor).
 * This is done in two steps: first issue a irq_set_affinity() on the
 * irq corresponding to the vcpu, then call its_schedule_vpe(). You
 * must be in a non-preemptible context. On exit, another call to
 * its_schedule_vpe() tells the redistributor that we're done with the
 * vcpu.
 *
 * Finally, the doorbell handling: Each vcpu is allocated an interrupt
 * which will fire each time a VLPI is made pending whilst the vcpu is
 * not running. Each time the vcpu gets blocked, the doorbell
 * interrupt gets enabled. When the vcpu is unblocked (for whatever
 * reason), the doorbell interrupt is disabled.
 */

#define DB_IRQ_FLAGS	(IRQ_NOAUTOEN | IRQ_DISABLE_UNLAZY | IRQ_NO_BALANCING)

static irqreturn_t vgic_v4_doorbell_handler(int irq, void *info)
{
	struct kvm_vcpu *vcpu = info;

	vcpu->arch.vgic_cpu.vgic_v3.its_vpe.pending_last = true;
	kvm_make_request(KVM_REQ_IRQ_PENDING, vcpu);
	kvm_vcpu_kick(vcpu);

	return IRQ_HANDLED;
}

/**
 * vgic_v4_init - Initialize the GICv4 data structures
 * @kvm:	Pointer to the VM being initialized
 *
 * We may be called each time a vITS is created, or when the
 * vgic is initialized. This relies on kvm->lock to be
 * held. In both cases, the number of vcpus should now be
 * fixed.
 */
int vgic_v4_init(struct kvm *kvm)
{
	struct vgic_dist *dist = &kvm->arch.vgic;
	struct kvm_vcpu *vcpu;
	int i, nr_vcpus, ret;

	if (!vgic_supports_direct_msis(kvm))
		return 0; /* Nothing to see here... move along. */

	if (dist->its_vm.vpes)
		return 0;

	nr_vcpus = atomic_read(&kvm->online_vcpus);

	dist->its_vm.vpes = kzalloc(sizeof(*dist->its_vm.vpes) * nr_vcpus,
				    GFP_KERNEL);
	if (!dist->its_vm.vpes)
		return -ENOMEM;

	dist->its_vm.nr_vpes = nr_vcpus;

	kvm_for_each_vcpu(i, vcpu, kvm)
		dist->its_vm.vpes[i] = &vcpu->arch.vgic_cpu.vgic_v3.its_vpe;

	ret = its_alloc_vcpu_irqs(&dist->its_vm);
	if (ret < 0) {
		kvm_err("VPE IRQ allocation failure\n");
		kfree(dist->its_vm.vpes);
		dist->its_vm.nr_vpes = 0;
		dist->its_vm.vpes = NULL;
		return ret;
	}

	kvm_for_each_vcpu(i, vcpu, kvm) {
		int irq = dist->its_vm.vpes[i]->irq;

		/*
		 * Don't automatically enable the doorbell, as we're
		 * flipping it back and forth when the vcpu gets
		 * blocked. Also disable the lazy disabling, as the
		 * doorbell could kick us out of the guest too
		 * early...
		 */
		irq_set_status_flags(irq, DB_IRQ_FLAGS);
		ret = request_irq(irq, vgic_v4_doorbell_handler,
				  0, "vcpu", vcpu);
		if (ret) {
			kvm_err("failed to allocate vcpu IRQ%d\n", irq);
			/*
			 * Trick: adjust the number of vpes so we know
			 * how many to nuke on teardown...
			 */
			dist->its_vm.nr_vpes = i;
			break;
		}
	}

	if (ret)
		vgic_v4_teardown(kvm);

	return ret;
}

/**
 * vgic_v4_teardown - Free the GICv4 data structures
 * @kvm:	Pointer to the VM being destroyed
 *
 * Relies on kvm->lock to be held.
 */
void vgic_v4_teardown(struct kvm *kvm)
{
	struct its_vm *its_vm = &kvm->arch.vgic.its_vm;
	int i;

	if (!its_vm->vpes)
		return;

	for (i = 0; i < its_vm->nr_vpes; i++) {
		struct kvm_vcpu *vcpu = kvm_get_vcpu(kvm, i);
		int irq = its_vm->vpes[i]->irq;

		irq_clear_status_flags(irq, DB_IRQ_FLAGS);
		free_irq(irq, vcpu);
	}

	its_free_vcpu_irqs(its_vm);
	kfree(its_vm->vpes);
	its_vm->nr_vpes = 0;
	its_vm->vpes = NULL;
}

int vgic_v4_sync_hwstate(struct kvm_vcpu *vcpu)
{
	if (!vgic_supports_direct_msis(vcpu->kvm))
		return 0;

	return its_schedule_vpe(&vcpu->arch.vgic_cpu.vgic_v3.its_vpe, false);
}

int vgic_v4_flush_hwstate(struct kvm_vcpu *vcpu)
{
	int irq = vcpu->arch.vgic_cpu.vgic_v3.its_vpe.irq;
	int err;

	if (!vgic_supports_direct_msis(vcpu->kvm))
		return 0;

	/*
	 * Before making the VPE resident, make sure the redistributor
	 * corresponding to our current CPU expects us here. See the
	 * doc in drivers/irqchip/irq-gic-v4.c to understand how this
	 * turns into a VMOVP command at the ITS level.
	 */
	err = irq_set_affinity(irq, cpumask_of(smp_processor_id()));
	if (err)
		return err;

	err = its_schedule_vpe(&vcpu->arch.vgic_cpu.vgic_v3.its_vpe, true);
	if (err)
		return err;

	/*
	 * Now that the VPE is resident, let's get rid of a potential
	 * doorbell interrupt that would still be pending.
	 */
	err = irq_set_irqchip_state(irq, IRQCHIP_STATE_PENDING, false);

	return err;
}

static struct vgic_its *vgic_get_its(struct kvm *kvm,
				     struct kvm_kernel_irq_routing_entry *irq_entry)
{
	struct kvm_msi msi  = (struct kvm_msi) {
		.address_lo	= irq_entry->msi.address_lo,
		.address_hi	= irq_entry->msi.address_hi,
		.data		= irq_entry->msi.data,
		.flags		= irq_entry->msi.flags,
		.devid		= irq_entry->msi.devid,
	};

	return vgic_msi_to_its(kvm, &msi);
}

int kvm_vgic_v4_set_forwarding(struct kvm *kvm, int virq,
			       struct kvm_kernel_irq_routing_entry *irq_entry)
{
	struct vgic_its *its;
	struct vgic_irq *irq;
	struct its_vlpi_map map;
	int ret;

	if (!vgic_supports_direct_msis(kvm))
		return 0;

	/*
	 * Get the ITS, and escape early on error (not a valid
	 * doorbell for any of our vITSs).
	 */
	its = vgic_get_its(kvm, irq_entry);
	if (IS_ERR(its))
		return 0;

	mutex_lock(&its->its_lock);

	/* Perform then actual DevID/EventID -> LPI translation. */
	ret = vgic_its_resolve_lpi(kvm, its, irq_entry->msi.devid,
				   irq_entry->msi.data, &irq);
	if (ret)
		goto out;

	/*
	 * Emit the mapping request. If it fails, the ITS probably
	 * isn't v4 compatible, so let's silently bail out. Holding
	 * the ITS lock should ensure that nothing can modify the
	 * target vcpu.
	 */
	map = (struct its_vlpi_map) {
		.vm		= &kvm->arch.vgic.its_vm,
		.vpe		= &irq->target_vcpu->arch.vgic_cpu.vgic_v3.its_vpe,
		.vintid		= irq->intid,
		.properties	= ((irq->priority & 0xfc) |
				   (irq->enabled ? LPI_PROP_ENABLED : 0) |
				   LPI_PROP_GROUP1),
		.db_enabled	= true,
	};

	ret = its_map_vlpi(virq, &map);
	if (ret)
		goto out;

	irq->hw		= true;
	irq->host_irq	= virq;

out:
	mutex_unlock(&its->its_lock);
	return ret;
}

int kvm_vgic_v4_unset_forwarding(struct kvm *kvm, int virq,
				 struct kvm_kernel_irq_routing_entry *irq_entry)
{
	struct vgic_its *its;
	struct vgic_irq *irq;
	int ret;

	if (!vgic_supports_direct_msis(kvm))
		return 0;

	/*
	 * Get the ITS, and escape early on error (not a valid
	 * doorbell for any of our vITSs).
	 */
	its = vgic_get_its(kvm, irq_entry);
	if (IS_ERR(its))
		return 0;

	mutex_lock(&its->its_lock);

	ret = vgic_its_resolve_lpi(kvm, its, irq_entry->msi.devid,
				   irq_entry->msi.data, &irq);
	if (ret)
		goto out;

	WARN_ON(!(irq->hw && irq->host_irq == virq));
	if (irq->hw) {
		irq->hw = false;
		ret = its_unmap_vlpi(virq);
	}

out:
	mutex_unlock(&its->its_lock);
	return ret;
}

void kvm_vgic_v4_enable_doorbell(struct kvm_vcpu *vcpu)
{
	if (vgic_supports_direct_msis(vcpu->kvm)) {
		int irq = vcpu->arch.vgic_cpu.vgic_v3.its_vpe.irq;
		if (irq)
			enable_irq(irq);
	}
}

void kvm_vgic_v4_disable_doorbell(struct kvm_vcpu *vcpu)
{
	if (vgic_supports_direct_msis(vcpu->kvm)) {
		int irq = vcpu->arch.vgic_cpu.vgic_v3.its_vpe.irq;
		if (irq)
			disable_irq(irq);
	}
}