1// SPDX-License-Identifier: GPL-2.0-only 2/* 3 * Copyright (C) 2017 ARM Ltd. 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/kvm_host.h> 11#include <linux/irqchip/arm-gic-v3.h> 12 13#include "vgic.h" 14 15/* 16 * How KVM uses GICv4 (insert rude comments here): 17 * 18 * The vgic-v4 layer acts as a bridge between several entities: 19 * - The GICv4 ITS representation offered by the ITS driver 20 * - VFIO, which is in charge of the PCI endpoint 21 * - The virtual ITS, which is the only thing the guest sees 22 * 23 * The configuration of VLPIs is triggered by a callback from VFIO, 24 * instructing KVM that a PCI device has been configured to deliver 25 * MSIs to a vITS. 26 * 27 * kvm_vgic_v4_set_forwarding() is thus called with the routing entry, 28 * and this is used to find the corresponding vITS data structures 29 * (ITS instance, device, event and irq) using a process that is 30 * extremely similar to the injection of an MSI. 31 * 32 * At this stage, we can link the guest's view of an LPI (uniquely 33 * identified by the routing entry) and the host irq, using the GICv4 34 * driver mapping operation. Should the mapping succeed, we've then 35 * successfully upgraded the guest's LPI to a VLPI. We can then start 36 * with updating GICv4's view of the property table and generating an 37 * INValidation in order to kickstart the delivery of this VLPI to the 38 * guest directly, without software intervention. Well, almost. 39 * 40 * When the PCI endpoint is deconfigured, this operation is reversed 41 * with VFIO calling kvm_vgic_v4_unset_forwarding(). 42 * 43 * Once the VLPI has been mapped, it needs to follow any change the 44 * guest performs on its LPI through the vITS. For that, a number of 45 * command handlers have hooks to communicate these changes to the HW: 46 * - Any invalidation triggers a call to its_prop_update_vlpi() 47 * - The INT command results in a irq_set_irqchip_state(), which 48 * generates an INT on the corresponding VLPI. 49 * - The CLEAR command results in a irq_set_irqchip_state(), which 50 * generates an CLEAR on the corresponding VLPI. 51 * - DISCARD translates into an unmap, similar to a call to 52 * kvm_vgic_v4_unset_forwarding(). 53 * - MOVI is translated by an update of the existing mapping, changing 54 * the target vcpu, resulting in a VMOVI being generated. 55 * - MOVALL is translated by a string of mapping updates (similar to 56 * the handling of MOVI). MOVALL is horrible. 57 * 58 * Note that a DISCARD/MAPTI sequence emitted from the guest without 59 * reprogramming the PCI endpoint after MAPTI does not result in a 60 * VLPI being mapped, as there is no callback from VFIO (the guest 61 * will get the interrupt via the normal SW injection). Fixing this is 62 * not trivial, and requires some horrible messing with the VFIO 63 * internals. Not fun. Don't do that. 64 * 65 * Then there is the scheduling. Each time a vcpu is about to run on a 66 * physical CPU, KVM must tell the corresponding redistributor about 67 * it. And if we've migrated our vcpu from one CPU to another, we must 68 * tell the ITS (so that the messages reach the right redistributor). 69 * This is done in two steps: first issue a irq_set_affinity() on the 70 * irq corresponding to the vcpu, then call its_make_vpe_resident(). 71 * You must be in a non-preemptible context. On exit, a call to 72 * its_make_vpe_non_resident() tells the redistributor that we're done 73 * with the vcpu. 74 * 75 * Finally, the doorbell handling: Each vcpu is allocated an interrupt 76 * which will fire each time a VLPI is made pending whilst the vcpu is 77 * not running. Each time the vcpu gets blocked, the doorbell 78 * interrupt gets enabled. When the vcpu is unblocked (for whatever 79 * reason), the doorbell interrupt is disabled. 80 */ 81 82#define DB_IRQ_FLAGS (IRQ_NOAUTOEN | IRQ_DISABLE_UNLAZY | IRQ_NO_BALANCING) 83 84static irqreturn_t vgic_v4_doorbell_handler(int irq, void *info) 85{ 86 struct kvm_vcpu *vcpu = info; 87 88 /* We got the message, no need to fire again */ 89 if (!kvm_vgic_global_state.has_gicv4_1 && 90 !irqd_irq_disabled(&irq_to_desc(irq)->irq_data)) 91 disable_irq_nosync(irq); 92 93 /* 94 * The v4.1 doorbell can fire concurrently with the vPE being 95 * made non-resident. Ensure we only update pending_last 96 * *after* the non-residency sequence has completed. 97 */ 98 raw_spin_lock(&vcpu->arch.vgic_cpu.vgic_v3.its_vpe.vpe_lock); 99 vcpu->arch.vgic_cpu.vgic_v3.its_vpe.pending_last = true; 100 raw_spin_unlock(&vcpu->arch.vgic_cpu.vgic_v3.its_vpe.vpe_lock); 101 102 kvm_make_request(KVM_REQ_IRQ_PENDING, vcpu); 103 kvm_vcpu_kick(vcpu); 104 105 return IRQ_HANDLED; 106} 107 108static void vgic_v4_sync_sgi_config(struct its_vpe *vpe, struct vgic_irq *irq) 109{ 110 vpe->sgi_config[irq->intid].enabled = irq->enabled; 111 vpe->sgi_config[irq->intid].group = irq->group; 112 vpe->sgi_config[irq->intid].priority = irq->priority; 113} 114 115static void vgic_v4_enable_vsgis(struct kvm_vcpu *vcpu) 116{ 117 struct its_vpe *vpe = &vcpu->arch.vgic_cpu.vgic_v3.its_vpe; 118 int i; 119 120 /* 121 * With GICv4.1, every virtual SGI can be directly injected. So 122 * let's pretend that they are HW interrupts, tied to a host 123 * IRQ. The SGI code will do its magic. 124 */ 125 for (i = 0; i < VGIC_NR_SGIS; i++) { 126 struct vgic_irq *irq = vgic_get_irq(vcpu->kvm, vcpu, i); 127 struct irq_desc *desc; 128 unsigned long flags; 129 int ret; 130 131 raw_spin_lock_irqsave(&irq->irq_lock, flags); 132 133 if (irq->hw) 134 goto unlock; 135 136 irq->hw = true; 137 irq->host_irq = irq_find_mapping(vpe->sgi_domain, i); 138 139 /* Transfer the full irq state to the vPE */ 140 vgic_v4_sync_sgi_config(vpe, irq); 141 desc = irq_to_desc(irq->host_irq); 142 ret = irq_domain_activate_irq(irq_desc_get_irq_data(desc), 143 false); 144 if (!WARN_ON(ret)) { 145 /* Transfer pending state */ 146 ret = irq_set_irqchip_state(irq->host_irq, 147 IRQCHIP_STATE_PENDING, 148 irq->pending_latch); 149 WARN_ON(ret); 150 irq->pending_latch = false; 151 } 152 unlock: 153 raw_spin_unlock_irqrestore(&irq->irq_lock, flags); 154 vgic_put_irq(vcpu->kvm, irq); 155 } 156} 157 158static void vgic_v4_disable_vsgis(struct kvm_vcpu *vcpu) 159{ 160 int i; 161 162 for (i = 0; i < VGIC_NR_SGIS; i++) { 163 struct vgic_irq *irq = vgic_get_irq(vcpu->kvm, vcpu, i); 164 struct irq_desc *desc; 165 unsigned long flags; 166 int ret; 167 168 raw_spin_lock_irqsave(&irq->irq_lock, flags); 169 170 if (!irq->hw) 171 goto unlock; 172 173 irq->hw = false; 174 ret = irq_get_irqchip_state(irq->host_irq, 175 IRQCHIP_STATE_PENDING, 176 &irq->pending_latch); 177 WARN_ON(ret); 178 179 desc = irq_to_desc(irq->host_irq); 180 irq_domain_deactivate_irq(irq_desc_get_irq_data(desc)); 181 unlock: 182 raw_spin_unlock_irqrestore(&irq->irq_lock, flags); 183 vgic_put_irq(vcpu->kvm, irq); 184 } 185} 186 187/* Must be called with the kvm lock held */ 188void vgic_v4_configure_vsgis(struct kvm *kvm) 189{ 190 struct vgic_dist *dist = &kvm->arch.vgic; 191 struct kvm_vcpu *vcpu; 192 int i; 193 194 kvm_arm_halt_guest(kvm); 195 196 kvm_for_each_vcpu(i, vcpu, kvm) { 197 if (dist->nassgireq) 198 vgic_v4_enable_vsgis(vcpu); 199 else 200 vgic_v4_disable_vsgis(vcpu); 201 } 202 203 kvm_arm_resume_guest(kvm); 204} 205 206/** 207 * vgic_v4_init - Initialize the GICv4 data structures 208 * @kvm: Pointer to the VM being initialized 209 * 210 * We may be called each time a vITS is created, or when the 211 * vgic is initialized. This relies on kvm->lock to be 212 * held. In both cases, the number of vcpus should now be 213 * fixed. 214 */ 215int vgic_v4_init(struct kvm *kvm) 216{ 217 struct vgic_dist *dist = &kvm->arch.vgic; 218 struct kvm_vcpu *vcpu; 219 int i, nr_vcpus, ret; 220 221 if (!kvm_vgic_global_state.has_gicv4) 222 return 0; /* Nothing to see here... move along. */ 223 224 if (dist->its_vm.vpes) 225 return 0; 226 227 nr_vcpus = atomic_read(&kvm->online_vcpus); 228 229 dist->its_vm.vpes = kcalloc(nr_vcpus, sizeof(*dist->its_vm.vpes), 230 GFP_KERNEL); 231 if (!dist->its_vm.vpes) 232 return -ENOMEM; 233 234 dist->its_vm.nr_vpes = nr_vcpus; 235 236 kvm_for_each_vcpu(i, vcpu, kvm) 237 dist->its_vm.vpes[i] = &vcpu->arch.vgic_cpu.vgic_v3.its_vpe; 238 239 ret = its_alloc_vcpu_irqs(&dist->its_vm); 240 if (ret < 0) { 241 kvm_err("VPE IRQ allocation failure\n"); 242 kfree(dist->its_vm.vpes); 243 dist->its_vm.nr_vpes = 0; 244 dist->its_vm.vpes = NULL; 245 return ret; 246 } 247 248 kvm_for_each_vcpu(i, vcpu, kvm) { 249 int irq = dist->its_vm.vpes[i]->irq; 250 unsigned long irq_flags = DB_IRQ_FLAGS; 251 252 /* 253 * Don't automatically enable the doorbell, as we're 254 * flipping it back and forth when the vcpu gets 255 * blocked. Also disable the lazy disabling, as the 256 * doorbell could kick us out of the guest too 257 * early... 258 * 259 * On GICv4.1, the doorbell is managed in HW and must 260 * be left enabled. 261 */ 262 if (kvm_vgic_global_state.has_gicv4_1) 263 irq_flags &= ~IRQ_NOAUTOEN; 264 irq_set_status_flags(irq, irq_flags); 265 266 ret = request_irq(irq, vgic_v4_doorbell_handler, 267 0, "vcpu", vcpu); 268 if (ret) { 269 kvm_err("failed to allocate vcpu IRQ%d\n", irq); 270 /* 271 * Trick: adjust the number of vpes so we know 272 * how many to nuke on teardown... 273 */ 274 dist->its_vm.nr_vpes = i; 275 break; 276 } 277 } 278 279 if (ret) 280 vgic_v4_teardown(kvm); 281 282 return ret; 283} 284 285/** 286 * vgic_v4_teardown - Free the GICv4 data structures 287 * @kvm: Pointer to the VM being destroyed 288 * 289 * Relies on kvm->lock to be held. 290 */ 291void vgic_v4_teardown(struct kvm *kvm) 292{ 293 struct its_vm *its_vm = &kvm->arch.vgic.its_vm; 294 int i; 295 296 if (!its_vm->vpes) 297 return; 298 299 for (i = 0; i < its_vm->nr_vpes; i++) { 300 struct kvm_vcpu *vcpu = kvm_get_vcpu(kvm, i); 301 int irq = its_vm->vpes[i]->irq; 302 303 irq_clear_status_flags(irq, DB_IRQ_FLAGS); 304 free_irq(irq, vcpu); 305 } 306 307 its_free_vcpu_irqs(its_vm); 308 kfree(its_vm->vpes); 309 its_vm->nr_vpes = 0; 310 its_vm->vpes = NULL; 311} 312 313int vgic_v4_put(struct kvm_vcpu *vcpu, bool need_db) 314{ 315 struct its_vpe *vpe = &vcpu->arch.vgic_cpu.vgic_v3.its_vpe; 316 317 if (!vgic_supports_direct_msis(vcpu->kvm) || !vpe->resident) 318 return 0; 319 320 return its_make_vpe_non_resident(vpe, need_db); 321} 322 323int vgic_v4_load(struct kvm_vcpu *vcpu) 324{ 325 struct its_vpe *vpe = &vcpu->arch.vgic_cpu.vgic_v3.its_vpe; 326 int err; 327 328 if (!vgic_supports_direct_msis(vcpu->kvm) || vpe->resident) 329 return 0; 330 331 /* 332 * Before making the VPE resident, make sure the redistributor 333 * corresponding to our current CPU expects us here. See the 334 * doc in drivers/irqchip/irq-gic-v4.c to understand how this 335 * turns into a VMOVP command at the ITS level. 336 */ 337 err = irq_set_affinity(vpe->irq, cpumask_of(smp_processor_id())); 338 if (err) 339 return err; 340 341 err = its_make_vpe_resident(vpe, false, vcpu->kvm->arch.vgic.enabled); 342 if (err) 343 return err; 344 345 /* 346 * Now that the VPE is resident, let's get rid of a potential 347 * doorbell interrupt that would still be pending. This is a 348 * GICv4.0 only "feature"... 349 */ 350 if (!kvm_vgic_global_state.has_gicv4_1) 351 err = irq_set_irqchip_state(vpe->irq, IRQCHIP_STATE_PENDING, false); 352 353 return err; 354} 355 356static struct vgic_its *vgic_get_its(struct kvm *kvm, 357 struct kvm_kernel_irq_routing_entry *irq_entry) 358{ 359 struct kvm_msi msi = (struct kvm_msi) { 360 .address_lo = irq_entry->msi.address_lo, 361 .address_hi = irq_entry->msi.address_hi, 362 .data = irq_entry->msi.data, 363 .flags = irq_entry->msi.flags, 364 .devid = irq_entry->msi.devid, 365 }; 366 367 return vgic_msi_to_its(kvm, &msi); 368} 369 370int kvm_vgic_v4_set_forwarding(struct kvm *kvm, int virq, 371 struct kvm_kernel_irq_routing_entry *irq_entry) 372{ 373 struct vgic_its *its; 374 struct vgic_irq *irq; 375 struct its_vlpi_map map; 376 int ret; 377 378 if (!vgic_supports_direct_msis(kvm)) 379 return 0; 380 381 /* 382 * Get the ITS, and escape early on error (not a valid 383 * doorbell for any of our vITSs). 384 */ 385 its = vgic_get_its(kvm, irq_entry); 386 if (IS_ERR(its)) 387 return 0; 388 389 mutex_lock(&its->its_lock); 390 391 /* Perform the actual DevID/EventID -> LPI translation. */ 392 ret = vgic_its_resolve_lpi(kvm, its, irq_entry->msi.devid, 393 irq_entry->msi.data, &irq); 394 if (ret) 395 goto out; 396 397 /* 398 * Emit the mapping request. If it fails, the ITS probably 399 * isn't v4 compatible, so let's silently bail out. Holding 400 * the ITS lock should ensure that nothing can modify the 401 * target vcpu. 402 */ 403 map = (struct its_vlpi_map) { 404 .vm = &kvm->arch.vgic.its_vm, 405 .vpe = &irq->target_vcpu->arch.vgic_cpu.vgic_v3.its_vpe, 406 .vintid = irq->intid, 407 .properties = ((irq->priority & 0xfc) | 408 (irq->enabled ? LPI_PROP_ENABLED : 0) | 409 LPI_PROP_GROUP1), 410 .db_enabled = true, 411 }; 412 413 ret = its_map_vlpi(virq, &map); 414 if (ret) 415 goto out; 416 417 irq->hw = true; 418 irq->host_irq = virq; 419 atomic_inc(&map.vpe->vlpi_count); 420 421out: 422 mutex_unlock(&its->its_lock); 423 return ret; 424} 425 426int kvm_vgic_v4_unset_forwarding(struct kvm *kvm, int virq, 427 struct kvm_kernel_irq_routing_entry *irq_entry) 428{ 429 struct vgic_its *its; 430 struct vgic_irq *irq; 431 int ret; 432 433 if (!vgic_supports_direct_msis(kvm)) 434 return 0; 435 436 /* 437 * Get the ITS, and escape early on error (not a valid 438 * doorbell for any of our vITSs). 439 */ 440 its = vgic_get_its(kvm, irq_entry); 441 if (IS_ERR(its)) 442 return 0; 443 444 mutex_lock(&its->its_lock); 445 446 ret = vgic_its_resolve_lpi(kvm, its, irq_entry->msi.devid, 447 irq_entry->msi.data, &irq); 448 if (ret) 449 goto out; 450 451 WARN_ON(!(irq->hw && irq->host_irq == virq)); 452 if (irq->hw) { 453 atomic_dec(&irq->target_vcpu->arch.vgic_cpu.vgic_v3.its_vpe.vlpi_count); 454 irq->hw = false; 455 ret = its_unmap_vlpi(virq); 456 } 457 458out: 459 mutex_unlock(&its->its_lock); 460 return ret; 461} 462