drivers/vfio/platform/vfio_platform_irq.c

   1 // SPDX-License-Identifier: GPL-2.0-only
   2 /*
   3  * VFIO platform devices interrupt handling
   4  *
   5  * Copyright (C) 2013 - Virtual Open Systems
   6  * Author: Antonios Motakis <a.motakis@virtualopensystems.com>
   7  */
   8
   9 #include <linux/eventfd.h>
  10 #include <linux/interrupt.h>
  11 #include <linux/slab.h>
  12 #include <linux/types.h>
  13 #include <linux/vfio.h>
  14 #include <linux/irq.h>
  15
  16 #include "vfio_platform_private.h"
  17
  18 static void vfio_platform_mask(struct vfio_platform_irq *irq_ctx)
  19 {
  20         unsigned long flags;
  21
  22         spin_lock_irqsave(&irq_ctx->lock, flags);
  23
  24         if (!irq_ctx->masked) {
  25                 disable_irq_nosync(irq_ctx->hwirq);
  26                 irq_ctx->masked = true;
  27         }
  28
  29         spin_unlock_irqrestore(&irq_ctx->lock, flags);
  30 }
  31
  32 static int vfio_platform_mask_handler(void *opaque, void *unused)
  33 {
  34         struct vfio_platform_irq *irq_ctx = opaque;
  35
  36         vfio_platform_mask(irq_ctx);
  37
  38         return 0;
  39 }
  40
  41 static int vfio_platform_set_irq_mask(struct vfio_platform_device *vdev,
  42                                       unsigned index, unsigned start,
  43                                       unsigned count, uint32_t flags,
  44                                       void *data)
  45 {
  46         if (start != 0 || count != 1)
  47                 return -EINVAL;
  48
  49         if (!(vdev->irqs[index].flags & VFIO_IRQ_INFO_MASKABLE))
  50                 return -EINVAL;
  51
  52         if (flags & VFIO_IRQ_SET_DATA_EVENTFD) {
  53                 int32_t fd = *(int32_t *)data;
  54
  55                 if (fd >= 0)
  56                         return vfio_virqfd_enable((void *) &vdev->irqs[index],
  57                                                   vfio_platform_mask_handler,
  58                                                   NULL, NULL,
  59                                                   &vdev->irqs[index].mask, fd);
  60
  61                 vfio_virqfd_disable(&vdev->irqs[index].mask);
  62                 return 0;
  63         }
  64
  65         if (flags & VFIO_IRQ_SET_DATA_NONE) {
  66                 vfio_platform_mask(&vdev->irqs[index]);
  67
  68         } else if (flags & VFIO_IRQ_SET_DATA_BOOL) {
  69                 uint8_t mask = *(uint8_t *)data;
  70
  71                 if (mask)
  72                         vfio_platform_mask(&vdev->irqs[index]);
  73         }
  74
  75         return 0;
  76 }
  77
  78 static void vfio_platform_unmask(struct vfio_platform_irq *irq_ctx)
  79 {
  80         unsigned long flags;
  81
  82         spin_lock_irqsave(&irq_ctx->lock, flags);
  83
  84         if (irq_ctx->masked) {
  85                 enable_irq(irq_ctx->hwirq);
  86                 irq_ctx->masked = false;
  87         }
  88
  89         spin_unlock_irqrestore(&irq_ctx->lock, flags);
  90 }
  91
  92 static int vfio_platform_unmask_handler(void *opaque, void *unused)
  93 {
  94         struct vfio_platform_irq *irq_ctx = opaque;
  95
  96         vfio_platform_unmask(irq_ctx);
  97
  98         return 0;
  99 }
 100
 101 static int vfio_platform_set_irq_unmask(struct vfio_platform_device *vdev,
 102                                         unsigned index, unsigned start,
 103                                         unsigned count, uint32_t flags,
 104                                         void *data)
 105 {
 106         if (start != 0 || count != 1)
 107                 return -EINVAL;
 108
 109         if (!(vdev->irqs[index].flags & VFIO_IRQ_INFO_MASKABLE))
 110                 return -EINVAL;
 111
 112         if (flags & VFIO_IRQ_SET_DATA_EVENTFD) {
 113                 int32_t fd = *(int32_t *)data;
 114
 115                 if (fd >= 0)
 116                         return vfio_virqfd_enable((void *) &vdev->irqs[index],
 117                                                   vfio_platform_unmask_handler,
 118                                                   NULL, NULL,
 119                                                   &vdev->irqs[index].unmask,
 120                                                   fd);
 121
 122                 vfio_virqfd_disable(&vdev->irqs[index].unmask);
 123                 return 0;
 124         }
 125
 126         if (flags & VFIO_IRQ_SET_DATA_NONE) {
 127                 vfio_platform_unmask(&vdev->irqs[index]);
 128
 129         } else if (flags & VFIO_IRQ_SET_DATA_BOOL) {
 130                 uint8_t unmask = *(uint8_t *)data;
 131
 132                 if (unmask)
 133                         vfio_platform_unmask(&vdev->irqs[index]);
 134         }
 135
 136         return 0;
 137 }
 138
 139 /*
 140  * The trigger eventfd is guaranteed valid in the interrupt path
 141  * and protected by the igate mutex when triggered via ioctl.
 142  */
 143 static void vfio_send_eventfd(struct vfio_platform_irq *irq_ctx)
 144 {
 145         if (likely(irq_ctx->trigger))
 146                 eventfd_signal(irq_ctx->trigger);
 147 }
 148
 149 static irqreturn_t vfio_automasked_irq_handler(int irq, void *dev_id)
 150 {
 151         struct vfio_platform_irq *irq_ctx = dev_id;
 152         unsigned long flags;
 153         int ret = IRQ_NONE;
 154
 155         spin_lock_irqsave(&irq_ctx->lock, flags);
 156
 157         if (!irq_ctx->masked) {
 158                 ret = IRQ_HANDLED;
 159
 160                 /* automask maskable interrupts */
 161                 disable_irq_nosync(irq_ctx->hwirq);
 162                 irq_ctx->masked = true;
 163         }
 164
 165         spin_unlock_irqrestore(&irq_ctx->lock, flags);
 166
 167         if (ret == IRQ_HANDLED)
 168                 vfio_send_eventfd(irq_ctx);
 169
 170         return ret;
 171 }
 172
 173 static irqreturn_t vfio_irq_handler(int irq, void *dev_id)
 174 {
 175         struct vfio_platform_irq *irq_ctx = dev_id;
 176
 177         vfio_send_eventfd(irq_ctx);
 178
 179         return IRQ_HANDLED;
 180 }
 181
 182 static int vfio_set_trigger(struct vfio_platform_device *vdev, int index,
 183                             int fd)
 184 {
 185         struct vfio_platform_irq *irq = &vdev->irqs[index];
 186         struct eventfd_ctx *trigger;
 187
 188         if (irq->trigger) {
 189                 disable_irq(irq->hwirq);
 190                 eventfd_ctx_put(irq->trigger);
 191                 irq->trigger = NULL;
 192         }
 193
 194         if (fd < 0) /* Disable only */
 195                 return 0;
 196
 197         trigger = eventfd_ctx_fdget(fd);
 198         if (IS_ERR(trigger))
 199                 return PTR_ERR(trigger);
 200
 201         irq->trigger = trigger;
 202
 203         /*
 204          * irq->masked effectively provides nested disables within the overall
 205          * enable relative to trigger.  Specifically request_irq() is called
 206          * with NO_AUTOEN, therefore the IRQ is initially disabled.  The user
 207          * may only further disable the IRQ with a MASK operations because
 208          * irq->masked is initially false.
 209          */
 210         enable_irq(irq->hwirq);
 211
 212         return 0;
 213 }
 214
 215 static int vfio_platform_set_irq_trigger(struct vfio_platform_device *vdev,
 216                                          unsigned index, unsigned start,
 217                                          unsigned count, uint32_t flags,
 218                                          void *data)
 219 {
 220         struct vfio_platform_irq *irq = &vdev->irqs[index];
 221         irq_handler_t handler;
 222
 223         if (vdev->irqs[index].flags & VFIO_IRQ_INFO_AUTOMASKED)
 224                 handler = vfio_automasked_irq_handler;
 225         else
 226                 handler = vfio_irq_handler;
 227
 228         if (!count && (flags & VFIO_IRQ_SET_DATA_NONE))
 229                 return vfio_set_trigger(vdev, index, -1);
 230
 231         if (start != 0 || count != 1)
 232                 return -EINVAL;
 233
 234         if (flags & VFIO_IRQ_SET_DATA_EVENTFD) {
 235                 int32_t fd = *(int32_t *)data;
 236
 237                 return vfio_set_trigger(vdev, index, fd);
 238         }
 239
 240         if (flags & VFIO_IRQ_SET_DATA_NONE) {
 241                 handler(irq->hwirq, irq);
 242
 243         } else if (flags & VFIO_IRQ_SET_DATA_BOOL) {
 244                 uint8_t trigger = *(uint8_t *)data;
 245
 246                 if (trigger)
 247                         handler(irq->hwirq, irq);
 248         }
 249
 250         return 0;
 251 }
 252
 253 int vfio_platform_set_irqs_ioctl(struct vfio_platform_device *vdev,
 254                                  uint32_t flags, unsigned index, unsigned start,
 255                                  unsigned count, void *data)
 256 {
 257         int (*func)(struct vfio_platform_device *vdev, unsigned index,
 258                     unsigned start, unsigned count, uint32_t flags,
 259                     void *data) = NULL;
 260
 261         /*
 262          * For compatibility, errors from request_irq() are local to the
 263          * SET_IRQS path and reflected in the name pointer.  This allows,
 264          * for example, polling mode fallback for an exclusive IRQ failure.
 265          */
 266         if (IS_ERR(vdev->irqs[index].name))
 267                 return PTR_ERR(vdev->irqs[index].name);
 268
 269         switch (flags & VFIO_IRQ_SET_ACTION_TYPE_MASK) {
 270         case VFIO_IRQ_SET_ACTION_MASK:
 271                 func = vfio_platform_set_irq_mask;
 272                 break;
 273         case VFIO_IRQ_SET_ACTION_UNMASK:
 274                 func = vfio_platform_set_irq_unmask;
 275                 break;
 276         case VFIO_IRQ_SET_ACTION_TRIGGER:
 277                 func = vfio_platform_set_irq_trigger;
 278                 break;
 279         }
 280
 281         if (!func)
 282                 return -ENOTTY;
 283
 284         return func(vdev, index, start, count, flags, data);
 285 }
 286
 287 int vfio_platform_irq_init(struct vfio_platform_device *vdev)
 288 {
 289         int cnt = 0, i, ret = 0;
 290
 291         while (vdev->get_irq(vdev, cnt) >= 0)
 292                 cnt++;
 293
 294         vdev->irqs = kcalloc(cnt, sizeof(struct vfio_platform_irq),
 295                              GFP_KERNEL_ACCOUNT);
 296         if (!vdev->irqs)
 297                 return -ENOMEM;
 298
 299         for (i = 0; i < cnt; i++) {
 300                 int hwirq = vdev->get_irq(vdev, i);
 301                 irq_handler_t handler = vfio_irq_handler;
 302
 303                 if (hwirq < 0) {
 304                         ret = -EINVAL;
 305                         goto err;
 306                 }
 307
 308                 spin_lock_init(&vdev->irqs[i].lock);
 309
 310                 vdev->irqs[i].flags = VFIO_IRQ_INFO_EVENTFD;
 311
 312                 if (irq_get_trigger_type(hwirq) & IRQ_TYPE_LEVEL_MASK) {
 313                         vdev->irqs[i].flags |= VFIO_IRQ_INFO_MASKABLE
 314                                                 | VFIO_IRQ_INFO_AUTOMASKED;
 315                         handler = vfio_automasked_irq_handler;
 316                 }
 317
 318                 vdev->irqs[i].count = 1;
 319                 vdev->irqs[i].hwirq = hwirq;
 320                 vdev->irqs[i].masked = false;
 321                 vdev->irqs[i].name = kasprintf(GFP_KERNEL_ACCOUNT,
 322                                                "vfio-irq[%d](%s)", hwirq,
 323                                                vdev->name);
 324                 if (!vdev->irqs[i].name) {
 325                         ret = -ENOMEM;
 326                         goto err;
 327                 }
 328
 329                 ret = request_irq(hwirq, handler, IRQF_NO_AUTOEN,
 330                                   vdev->irqs[i].name, &vdev->irqs[i]);
 331                 if (ret) {
 332                         kfree(vdev->irqs[i].name);
 333                         vdev->irqs[i].name = ERR_PTR(ret);
 334                 }
 335         }
 336
 337         vdev->num_irqs = cnt;
 338
 339         return 0;
 340 err:
 341         for (--i; i >= 0; i--) {
 342                 if (!IS_ERR(vdev->irqs[i].name)) {
 343                         free_irq(vdev->irqs[i].hwirq, &vdev->irqs[i]);
 344                         kfree(vdev->irqs[i].name);
 345                 }
 346         }
 347         kfree(vdev->irqs);
 348         return ret;
 349 }
 350
 351 void vfio_platform_irq_cleanup(struct vfio_platform_device *vdev)
 352 {
 353         int i;
 354
 355         for (i = 0; i < vdev->num_irqs; i++) {
 356                 vfio_virqfd_disable(&vdev->irqs[i].mask);
 357                 vfio_virqfd_disable(&vdev->irqs[i].unmask);
 358                 if (!IS_ERR(vdev->irqs[i].name)) {
 359                         free_irq(vdev->irqs[i].hwirq, &vdev->irqs[i]);
 360                         if (vdev->irqs[i].trigger)
 361                                 eventfd_ctx_put(vdev->irqs[i].trigger);
 362                         kfree(vdev->irqs[i].name);
 363                 }
 364         }
 365
 366         vdev->num_irqs = 0;
 367         kfree(vdev->irqs);
 368 }