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 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 102 bool gic_cpuif_has_vsgi(void) 103 { 104 return false; 105 } 106 #endif 107 108 static bool has_v4_1(void) 109 { 110 return !!sgi_domain_ops; 111 } 112 113 static bool has_v4_1_sgi(void) 114 { 115 return has_v4_1() && gic_cpuif_has_vsgi(); 116 } 117 118 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 } 156 157 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 } 200 201 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 } 219 220 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 } 227 228 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 } 232 233 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 } 259 260 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 } 282 283 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 } 298 299 300 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 } 308 309 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 } 331 332 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 } 343 344 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 } 349 350 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 } 361 362 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 } 374 375 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