drivers/crypto/ccp/tee-dev.c

   1 // SPDX-License-Identifier: MIT
   2 /*
   3  * AMD Trusted Execution Environment (TEE) interface
   4  *
   5  * Author: Rijo Thomas <Rijo-john.Thomas@amd.com>
   6  * Author: Devaraj Rangasamy <Devaraj.Rangasamy@amd.com>
   7  *
   8  * Copyright (C) 2019,2021 Advanced Micro Devices, Inc.
   9  */
  10
  11 #include <linux/types.h>
  12 #include <linux/mutex.h>
  13 #include <linux/delay.h>
  14 #include <linux/slab.h>
  15 #include <linux/gfp.h>
  16 #include <linux/psp-sev.h>
  17 #include <linux/psp-tee.h>
  18
  19 #include "psp-dev.h"
  20 #include "tee-dev.h"
  21
  22 static bool psp_dead;
  23
  24 static int tee_alloc_ring(struct psp_tee_device *tee, int ring_size)
  25 {
  26         struct ring_buf_manager *rb_mgr = &tee->rb_mgr;
  27         void *start_addr;
  28
  29         if (!ring_size)
  30                 return -EINVAL;
  31
  32         /* We need actual physical address instead of DMA address, since
  33          * Trusted OS running on AMD Secure Processor will map this region
  34          */
  35         start_addr = (void *)__get_free_pages(GFP_KERNEL, get_order(ring_size));
  36         if (!start_addr)
  37                 return -ENOMEM;
  38
  39         memset(start_addr, 0x0, ring_size);
  40         rb_mgr->ring_start = start_addr;
  41         rb_mgr->ring_size = ring_size;
  42         rb_mgr->ring_pa = __psp_pa(start_addr);
  43         mutex_init(&rb_mgr->mutex);
  44
  45         return 0;
  46 }
  47
  48 static void tee_free_ring(struct psp_tee_device *tee)
  49 {
  50         struct ring_buf_manager *rb_mgr = &tee->rb_mgr;
  51
  52         if (!rb_mgr->ring_start)
  53                 return;
  54
  55         free_pages((unsigned long)rb_mgr->ring_start,
  56                    get_order(rb_mgr->ring_size));
  57
  58         rb_mgr->ring_start = NULL;
  59         rb_mgr->ring_size = 0;
  60         rb_mgr->ring_pa = 0;
  61         mutex_destroy(&rb_mgr->mutex);
  62 }
  63
  64 static int tee_wait_cmd_poll(struct psp_tee_device *tee, unsigned int timeout,
  65                              unsigned int *reg)
  66 {
  67         /* ~10ms sleep per loop => nloop = timeout * 100 */
  68         int nloop = timeout * 100;
  69
  70         while (--nloop) {
  71                 *reg = ioread32(tee->io_regs + tee->vdata->cmdresp_reg);
  72                 if (*reg & PSP_CMDRESP_RESP)
  73                         return 0;
  74
  75                 usleep_range(10000, 10100);
  76         }
  77
  78         dev_err(tee->dev, "tee: command timed out, disabling PSP\n");
  79         psp_dead = true;
  80
  81         return -ETIMEDOUT;
  82 }
  83
  84 static
  85 struct tee_init_ring_cmd *tee_alloc_cmd_buffer(struct psp_tee_device *tee)
  86 {
  87         struct tee_init_ring_cmd *cmd;
  88
  89         cmd = kzalloc(sizeof(*cmd), GFP_KERNEL);
  90         if (!cmd)
  91                 return NULL;
  92
  93         cmd->hi_addr = upper_32_bits(tee->rb_mgr.ring_pa);
  94         cmd->low_addr = lower_32_bits(tee->rb_mgr.ring_pa);
  95         cmd->size = tee->rb_mgr.ring_size;
  96
  97         dev_dbg(tee->dev, "tee: ring address: high = 0x%x low = 0x%x size = %u\n",
  98                 cmd->hi_addr, cmd->low_addr, cmd->size);
  99
 100         return cmd;
 101 }
 102
 103 static inline void tee_free_cmd_buffer(struct tee_init_ring_cmd *cmd)
 104 {
 105         kfree(cmd);
 106 }
 107
 108 static int tee_init_ring(struct psp_tee_device *tee)
 109 {
 110         int ring_size = MAX_RING_BUFFER_ENTRIES * sizeof(struct tee_ring_cmd);
 111         struct tee_init_ring_cmd *cmd;
 112         phys_addr_t cmd_buffer;
 113         unsigned int reg;
 114         int ret;
 115
 116         BUILD_BUG_ON(sizeof(struct tee_ring_cmd) != 1024);
 117
 118         ret = tee_alloc_ring(tee, ring_size);
 119         if (ret) {
 120                 dev_err(tee->dev, "tee: ring allocation failed %d\n", ret);
 121                 return ret;
 122         }
 123
 124         tee->rb_mgr.wptr = 0;
 125
 126         cmd = tee_alloc_cmd_buffer(tee);
 127         if (!cmd) {
 128                 tee_free_ring(tee);
 129                 return -ENOMEM;
 130         }
 131
 132         cmd_buffer = __psp_pa((void *)cmd);
 133
 134         /* Send command buffer details to Trusted OS by writing to
 135          * CPU-PSP message registers
 136          */
 137
 138         iowrite32(lower_32_bits(cmd_buffer),
 139                   tee->io_regs + tee->vdata->cmdbuff_addr_lo_reg);
 140         iowrite32(upper_32_bits(cmd_buffer),
 141                   tee->io_regs + tee->vdata->cmdbuff_addr_hi_reg);
 142         iowrite32(TEE_RING_INIT_CMD,
 143                   tee->io_regs + tee->vdata->cmdresp_reg);
 144
 145         ret = tee_wait_cmd_poll(tee, TEE_DEFAULT_TIMEOUT, &reg);
 146         if (ret) {
 147                 dev_err(tee->dev, "tee: ring init command timed out\n");
 148                 tee_free_ring(tee);
 149                 goto free_buf;
 150         }
 151
 152         if (reg & PSP_CMDRESP_ERR_MASK) {
 153                 dev_err(tee->dev, "tee: ring init command failed (%#010x)\n",
 154                         reg & PSP_CMDRESP_ERR_MASK);
 155                 tee_free_ring(tee);
 156                 ret = -EIO;
 157         }
 158
 159 free_buf:
 160         tee_free_cmd_buffer(cmd);
 161
 162         return ret;
 163 }
 164
 165 static void tee_destroy_ring(struct psp_tee_device *tee)
 166 {
 167         unsigned int reg;
 168         int ret;
 169
 170         if (!tee->rb_mgr.ring_start)
 171                 return;
 172
 173         if (psp_dead)
 174                 goto free_ring;
 175
 176         iowrite32(TEE_RING_DESTROY_CMD,
 177                   tee->io_regs + tee->vdata->cmdresp_reg);
 178
 179         ret = tee_wait_cmd_poll(tee, TEE_DEFAULT_TIMEOUT, &reg);
 180         if (ret) {
 181                 dev_err(tee->dev, "tee: ring destroy command timed out\n");
 182         } else if (reg & PSP_CMDRESP_ERR_MASK) {
 183                 dev_err(tee->dev, "tee: ring destroy command failed (%#010x)\n",
 184                         reg & PSP_CMDRESP_ERR_MASK);
 185         }
 186
 187 free_ring:
 188         tee_free_ring(tee);
 189 }
 190
 191 int tee_dev_init(struct psp_device *psp)
 192 {
 193         struct device *dev = psp->dev;
 194         struct psp_tee_device *tee;
 195         int ret;
 196
 197         ret = -ENOMEM;
 198         tee = devm_kzalloc(dev, sizeof(*tee), GFP_KERNEL);
 199         if (!tee)
 200                 goto e_err;
 201
 202         psp->tee_data = tee;
 203
 204         tee->dev = dev;
 205         tee->psp = psp;
 206
 207         tee->io_regs = psp->io_regs;
 208
 209         tee->vdata = (struct tee_vdata *)psp->vdata->tee;
 210         if (!tee->vdata) {
 211                 ret = -ENODEV;
 212                 dev_err(dev, "tee: missing driver data\n");
 213                 goto e_err;
 214         }
 215
 216         ret = tee_init_ring(tee);
 217         if (ret) {
 218                 dev_err(dev, "tee: failed to init ring buffer\n");
 219                 goto e_err;
 220         }
 221
 222         dev_notice(dev, "tee enabled\n");
 223
 224         return 0;
 225
 226 e_err:
 227         psp->tee_data = NULL;
 228
 229         dev_notice(dev, "tee initialization failed\n");
 230
 231         return ret;
 232 }
 233
 234 void tee_dev_destroy(struct psp_device *psp)
 235 {
 236         struct psp_tee_device *tee = psp->tee_data;
 237
 238         if (!tee)
 239                 return;
 240
 241         tee_destroy_ring(tee);
 242 }
 243
 244 static int tee_submit_cmd(struct psp_tee_device *tee, enum tee_cmd_id cmd_id,
 245                           void *buf, size_t len, struct tee_ring_cmd **resp)
 246 {
 247         struct tee_ring_cmd *cmd;
 248         int nloop = 1000, ret = 0;
 249         u32 rptr;
 250
 251         *resp = NULL;
 252
 253         mutex_lock(&tee->rb_mgr.mutex);
 254
 255         /* Loop until empty entry found in ring buffer */
 256         do {
 257                 /* Get pointer to ring buffer command entry */
 258                 cmd = (struct tee_ring_cmd *)
 259                         (tee->rb_mgr.ring_start + tee->rb_mgr.wptr);
 260
 261                 rptr = ioread32(tee->io_regs + tee->vdata->ring_rptr_reg);
 262
 263                 /* Check if ring buffer is full or command entry is waiting
 264                  * for response from TEE
 265                  */
 266                 if (!(tee->rb_mgr.wptr + sizeof(struct tee_ring_cmd) == rptr ||
 267                       cmd->flag == CMD_WAITING_FOR_RESPONSE))
 268                         break;
 269
 270                 dev_dbg(tee->dev, "tee: ring buffer full. rptr = %u wptr = %u\n",
 271                         rptr, tee->rb_mgr.wptr);
 272
 273                 /* Wait if ring buffer is full or TEE is processing data */
 274                 mutex_unlock(&tee->rb_mgr.mutex);
 275                 schedule_timeout_interruptible(msecs_to_jiffies(10));
 276                 mutex_lock(&tee->rb_mgr.mutex);
 277
 278         } while (--nloop);
 279
 280         if (!nloop &&
 281             (tee->rb_mgr.wptr + sizeof(struct tee_ring_cmd) == rptr ||
 282              cmd->flag == CMD_WAITING_FOR_RESPONSE)) {
 283                 dev_err(tee->dev, "tee: ring buffer full. rptr = %u wptr = %u response flag %u\n",
 284                         rptr, tee->rb_mgr.wptr, cmd->flag);
 285                 ret = -EBUSY;
 286                 goto unlock;
 287         }
 288
 289         /* Do not submit command if PSP got disabled while processing any
 290          * command in another thread
 291          */
 292         if (psp_dead) {
 293                 ret = -EBUSY;
 294                 goto unlock;
 295         }
 296
 297         /* Write command data into ring buffer */
 298         cmd->cmd_id = cmd_id;
 299         cmd->cmd_state = TEE_CMD_STATE_INIT;
 300         memset(&cmd->buf[0], 0, sizeof(cmd->buf));
 301         memcpy(&cmd->buf[0], buf, len);
 302
 303         /* Indicate driver is waiting for response */
 304         cmd->flag = CMD_WAITING_FOR_RESPONSE;
 305
 306         /* Update local copy of write pointer */
 307         tee->rb_mgr.wptr += sizeof(struct tee_ring_cmd);
 308         if (tee->rb_mgr.wptr >= tee->rb_mgr.ring_size)
 309                 tee->rb_mgr.wptr = 0;
 310
 311         /* Trigger interrupt to Trusted OS */
 312         iowrite32(tee->rb_mgr.wptr, tee->io_regs + tee->vdata->ring_wptr_reg);
 313
 314         /* The response is provided by Trusted OS in same
 315          * location as submitted data entry within ring buffer.
 316          */
 317         *resp = cmd;
 318
 319 unlock:
 320         mutex_unlock(&tee->rb_mgr.mutex);
 321
 322         return ret;
 323 }
 324
 325 static int tee_wait_cmd_completion(struct psp_tee_device *tee,
 326                                    struct tee_ring_cmd *resp,
 327                                    unsigned int timeout)
 328 {
 329         /* ~1ms sleep per loop => nloop = timeout * 1000 */
 330         int nloop = timeout * 1000;
 331
 332         while (--nloop) {
 333                 if (resp->cmd_state == TEE_CMD_STATE_COMPLETED)
 334                         return 0;
 335
 336                 usleep_range(1000, 1100);
 337         }
 338
 339         dev_err(tee->dev, "tee: command 0x%x timed out, disabling PSP\n",
 340                 resp->cmd_id);
 341
 342         psp_dead = true;
 343
 344         return -ETIMEDOUT;
 345 }
 346
 347 int psp_tee_process_cmd(enum tee_cmd_id cmd_id, void *buf, size_t len,
 348                         u32 *status)
 349 {
 350         struct psp_device *psp = psp_get_master_device();
 351         struct psp_tee_device *tee;
 352         struct tee_ring_cmd *resp;
 353         int ret;
 354
 355         if (!buf || !status || !len || len > sizeof(resp->buf))
 356                 return -EINVAL;
 357
 358         *status = 0;
 359
 360         if (!psp || !psp->tee_data)
 361                 return -ENODEV;
 362
 363         if (psp_dead)
 364                 return -EBUSY;
 365
 366         tee = psp->tee_data;
 367
 368         ret = tee_submit_cmd(tee, cmd_id, buf, len, &resp);
 369         if (ret)
 370                 return ret;
 371
 372         ret = tee_wait_cmd_completion(tee, resp, TEE_DEFAULT_TIMEOUT);
 373         if (ret) {
 374                 resp->flag = CMD_RESPONSE_TIMEDOUT;
 375                 return ret;
 376         }
 377
 378         memcpy(buf, &resp->buf[0], len);
 379         *status = resp->status;
 380
 381         resp->flag = CMD_RESPONSE_COPIED;
 382
 383         return 0;
 384 }
 385 EXPORT_SYMBOL(psp_tee_process_cmd);
 386
 387 int psp_check_tee_status(void)
 388 {
 389         struct psp_device *psp = psp_get_master_device();
 390
 391         if (!psp || !psp->tee_data)
 392                 return -ENODEV;
 393
 394         return 0;
 395 }
 396 EXPORT_SYMBOL(psp_check_tee_status);