1 // SPDX-License-Identifier: GPL-2.0-only 2 /* 3 * AMD Secure Encrypted Virtualization (SEV) guest driver interface 4 * 5 * Copyright (C) 2021 Advanced Micro Devices, Inc. 6 * 7 * Author: Brijesh Singh <brijesh.singh@amd.com> 8 */ 9 10 #include <linux/module.h> 11 #include <linux/kernel.h> 12 #include <linux/types.h> 13 #include <linux/mutex.h> 14 #include <linux/io.h> 15 #include <linux/platform_device.h> 16 #include <linux/miscdevice.h> 17 #include <linux/set_memory.h> 18 #include <linux/fs.h> 19 #include <crypto/aead.h> 20 #include <linux/scatterlist.h> 21 #include <linux/psp-sev.h> 22 #include <uapi/linux/sev-guest.h> 23 #include <uapi/linux/psp-sev.h> 24 25 #include <asm/svm.h> 26 #include <asm/sev.h> 27 28 #include "sev-guest.h" 29 30 #define DEVICE_NAME "sev-guest" 31 #define AAD_LEN 48 32 #define MSG_HDR_VER 1 33 34 struct snp_guest_crypto { 35 struct crypto_aead *tfm; 36 u8 *iv, *authtag; 37 int iv_len, a_len; 38 }; 39 40 struct snp_guest_dev { 41 struct device *dev; 42 struct miscdevice misc; 43 44 void *certs_data; 45 struct snp_guest_crypto *crypto; 46 struct snp_guest_msg *request, *response; 47 struct snp_secrets_page_layout *layout; 48 struct snp_req_data input; 49 u32 *os_area_msg_seqno; 50 u8 *vmpck; 51 }; 52 53 static u32 vmpck_id; 54 module_param(vmpck_id, uint, 0444); 55 MODULE_PARM_DESC(vmpck_id, "The VMPCK ID to use when communicating with the PSP."); 56 57 /* Mutex to serialize the shared buffer access and command handling. */ 58 static DEFINE_MUTEX(snp_cmd_mutex); 59 60 static bool is_vmpck_empty(struct snp_guest_dev *snp_dev) 61 { 62 char zero_key[VMPCK_KEY_LEN] = {0}; 63 64 if (snp_dev->vmpck) 65 return !memcmp(snp_dev->vmpck, zero_key, VMPCK_KEY_LEN); 66 67 return true; 68 } 69 70 /* 71 * If an error is received from the host or AMD Secure Processor (ASP) there 72 * are two options. Either retry the exact same encrypted request or discontinue 73 * using the VMPCK. 74 * 75 * This is because in the current encryption scheme GHCB v2 uses AES-GCM to 76 * encrypt the requests. The IV for this scheme is the sequence number. GCM 77 * cannot tolerate IV reuse. 78 * 79 * The ASP FW v1.51 only increments the sequence numbers on a successful 80 * guest<->ASP back and forth and only accepts messages at its exact sequence 81 * number. 82 * 83 * So if the sequence number were to be reused the encryption scheme is 84 * vulnerable. If the sequence number were incremented for a fresh IV the ASP 85 * will reject the request. 86 */ 87 static void snp_disable_vmpck(struct snp_guest_dev *snp_dev) 88 { 89 dev_alert(snp_dev->dev, "Disabling vmpck_id %d to prevent IV reuse.\n", 90 vmpck_id); 91 memzero_explicit(snp_dev->vmpck, VMPCK_KEY_LEN); 92 snp_dev->vmpck = NULL; 93 } 94 95 static inline u64 __snp_get_msg_seqno(struct snp_guest_dev *snp_dev) 96 { 97 u64 count; 98 99 lockdep_assert_held(&snp_cmd_mutex); 100 101 /* Read the current message sequence counter from secrets pages */ 102 count = *snp_dev->os_area_msg_seqno; 103 104 return count + 1; 105 } 106 107 /* Return a non-zero on success */ 108 static u64 snp_get_msg_seqno(struct snp_guest_dev *snp_dev) 109 { 110 u64 count = __snp_get_msg_seqno(snp_dev); 111 112 /* 113 * The message sequence counter for the SNP guest request is a 64-bit 114 * value but the version 2 of GHCB specification defines a 32-bit storage 115 * for it. If the counter exceeds the 32-bit value then return zero. 116 * The caller should check the return value, but if the caller happens to 117 * not check the value and use it, then the firmware treats zero as an 118 * invalid number and will fail the message request. 119 */ 120 if (count >= UINT_MAX) { 121 dev_err(snp_dev->dev, "request message sequence counter overflow\n"); 122 return 0; 123 } 124 125 return count; 126 } 127 128 static void snp_inc_msg_seqno(struct snp_guest_dev *snp_dev) 129 { 130 /* 131 * The counter is also incremented by the PSP, so increment it by 2 132 * and save in secrets page. 133 */ 134 *snp_dev->os_area_msg_seqno += 2; 135 } 136 137 static inline struct snp_guest_dev *to_snp_dev(struct file *file) 138 { 139 struct miscdevice *dev = file->private_data; 140 141 return container_of(dev, struct snp_guest_dev, misc); 142 } 143 144 static struct snp_guest_crypto *init_crypto(struct snp_guest_dev *snp_dev, u8 *key, size_t keylen) 145 { 146 struct snp_guest_crypto *crypto; 147 148 crypto = kzalloc(sizeof(*crypto), GFP_KERNEL_ACCOUNT); 149 if (!crypto) 150 return NULL; 151 152 crypto->tfm = crypto_alloc_aead("gcm(aes)", 0, 0); 153 if (IS_ERR(crypto->tfm)) 154 goto e_free; 155 156 if (crypto_aead_setkey(crypto->tfm, key, keylen)) 157 goto e_free_crypto; 158 159 crypto->iv_len = crypto_aead_ivsize(crypto->tfm); 160 crypto->iv = kmalloc(crypto->iv_len, GFP_KERNEL_ACCOUNT); 161 if (!crypto->iv) 162 goto e_free_crypto; 163 164 if (crypto_aead_authsize(crypto->tfm) > MAX_AUTHTAG_LEN) { 165 if (crypto_aead_setauthsize(crypto->tfm, MAX_AUTHTAG_LEN)) { 166 dev_err(snp_dev->dev, "failed to set authsize to %d\n", MAX_AUTHTAG_LEN); 167 goto e_free_iv; 168 } 169 } 170 171 crypto->a_len = crypto_aead_authsize(crypto->tfm); 172 crypto->authtag = kmalloc(crypto->a_len, GFP_KERNEL_ACCOUNT); 173 if (!crypto->authtag) 174 goto e_free_auth; 175 176 return crypto; 177 178 e_free_auth: 179 kfree(crypto->authtag); 180 e_free_iv: 181 kfree(crypto->iv); 182 e_free_crypto: 183 crypto_free_aead(crypto->tfm); 184 e_free: 185 kfree(crypto); 186 187 return NULL; 188 } 189 190 static void deinit_crypto(struct snp_guest_crypto *crypto) 191 { 192 crypto_free_aead(crypto->tfm); 193 kfree(crypto->iv); 194 kfree(crypto->authtag); 195 kfree(crypto); 196 } 197 198 static int enc_dec_message(struct snp_guest_crypto *crypto, struct snp_guest_msg *msg, 199 u8 *src_buf, u8 *dst_buf, size_t len, bool enc) 200 { 201 struct snp_guest_msg_hdr *hdr = &msg->hdr; 202 struct scatterlist src[3], dst[3]; 203 DECLARE_CRYPTO_WAIT(wait); 204 struct aead_request *req; 205 int ret; 206 207 req = aead_request_alloc(crypto->tfm, GFP_KERNEL); 208 if (!req) 209 return -ENOMEM; 210 211 /* 212 * AEAD memory operations: 213 * +------ AAD -------+------- DATA -----+---- AUTHTAG----+ 214 * | msg header | plaintext | hdr->authtag | 215 * | bytes 30h - 5Fh | or | | 216 * | | cipher | | 217 * +------------------+------------------+----------------+ 218 */ 219 sg_init_table(src, 3); 220 sg_set_buf(&src[0], &hdr->algo, AAD_LEN); 221 sg_set_buf(&src[1], src_buf, hdr->msg_sz); 222 sg_set_buf(&src[2], hdr->authtag, crypto->a_len); 223 224 sg_init_table(dst, 3); 225 sg_set_buf(&dst[0], &hdr->algo, AAD_LEN); 226 sg_set_buf(&dst[1], dst_buf, hdr->msg_sz); 227 sg_set_buf(&dst[2], hdr->authtag, crypto->a_len); 228 229 aead_request_set_ad(req, AAD_LEN); 230 aead_request_set_tfm(req, crypto->tfm); 231 aead_request_set_callback(req, 0, crypto_req_done, &wait); 232 233 aead_request_set_crypt(req, src, dst, len, crypto->iv); 234 ret = crypto_wait_req(enc ? crypto_aead_encrypt(req) : crypto_aead_decrypt(req), &wait); 235 236 aead_request_free(req); 237 return ret; 238 } 239 240 static int __enc_payload(struct snp_guest_dev *snp_dev, struct snp_guest_msg *msg, 241 void *plaintext, size_t len) 242 { 243 struct snp_guest_crypto *crypto = snp_dev->crypto; 244 struct snp_guest_msg_hdr *hdr = &msg->hdr; 245 246 memset(crypto->iv, 0, crypto->iv_len); 247 memcpy(crypto->iv, &hdr->msg_seqno, sizeof(hdr->msg_seqno)); 248 249 return enc_dec_message(crypto, msg, plaintext, msg->payload, len, true); 250 } 251 252 static int dec_payload(struct snp_guest_dev *snp_dev, struct snp_guest_msg *msg, 253 void *plaintext, size_t len) 254 { 255 struct snp_guest_crypto *crypto = snp_dev->crypto; 256 struct snp_guest_msg_hdr *hdr = &msg->hdr; 257 258 /* Build IV with response buffer sequence number */ 259 memset(crypto->iv, 0, crypto->iv_len); 260 memcpy(crypto->iv, &hdr->msg_seqno, sizeof(hdr->msg_seqno)); 261 262 return enc_dec_message(crypto, msg, msg->payload, plaintext, len, false); 263 } 264 265 static int verify_and_dec_payload(struct snp_guest_dev *snp_dev, void *payload, u32 sz) 266 { 267 struct snp_guest_crypto *crypto = snp_dev->crypto; 268 struct snp_guest_msg *resp = snp_dev->response; 269 struct snp_guest_msg *req = snp_dev->request; 270 struct snp_guest_msg_hdr *req_hdr = &req->hdr; 271 struct snp_guest_msg_hdr *resp_hdr = &resp->hdr; 272 273 dev_dbg(snp_dev->dev, "response [seqno %lld type %d version %d sz %d]\n", 274 resp_hdr->msg_seqno, resp_hdr->msg_type, resp_hdr->msg_version, resp_hdr->msg_sz); 275 276 /* Verify that the sequence counter is incremented by 1 */ 277 if (unlikely(resp_hdr->msg_seqno != (req_hdr->msg_seqno + 1))) 278 return -EBADMSG; 279 280 /* Verify response message type and version number. */ 281 if (resp_hdr->msg_type != (req_hdr->msg_type + 1) || 282 resp_hdr->msg_version != req_hdr->msg_version) 283 return -EBADMSG; 284 285 /* 286 * If the message size is greater than our buffer length then return 287 * an error. 288 */ 289 if (unlikely((resp_hdr->msg_sz + crypto->a_len) > sz)) 290 return -EBADMSG; 291 292 /* Decrypt the payload */ 293 return dec_payload(snp_dev, resp, payload, resp_hdr->msg_sz + crypto->a_len); 294 } 295 296 static int enc_payload(struct snp_guest_dev *snp_dev, u64 seqno, int version, u8 type, 297 void *payload, size_t sz) 298 { 299 struct snp_guest_msg *req = snp_dev->request; 300 struct snp_guest_msg_hdr *hdr = &req->hdr; 301 302 memset(req, 0, sizeof(*req)); 303 304 hdr->algo = SNP_AEAD_AES_256_GCM; 305 hdr->hdr_version = MSG_HDR_VER; 306 hdr->hdr_sz = sizeof(*hdr); 307 hdr->msg_type = type; 308 hdr->msg_version = version; 309 hdr->msg_seqno = seqno; 310 hdr->msg_vmpck = vmpck_id; 311 hdr->msg_sz = sz; 312 313 /* Verify the sequence number is non-zero */ 314 if (!hdr->msg_seqno) 315 return -ENOSR; 316 317 dev_dbg(snp_dev->dev, "request [seqno %lld type %d version %d sz %d]\n", 318 hdr->msg_seqno, hdr->msg_type, hdr->msg_version, hdr->msg_sz); 319 320 return __enc_payload(snp_dev, req, payload, sz); 321 } 322 323 static int handle_guest_request(struct snp_guest_dev *snp_dev, u64 exit_code, int msg_ver, 324 u8 type, void *req_buf, size_t req_sz, void *resp_buf, 325 u32 resp_sz, __u64 *fw_err) 326 { 327 unsigned long err; 328 u64 seqno; 329 int rc; 330 331 /* Get message sequence and verify that its a non-zero */ 332 seqno = snp_get_msg_seqno(snp_dev); 333 if (!seqno) 334 return -EIO; 335 336 memset(snp_dev->response, 0, sizeof(struct snp_guest_msg)); 337 338 /* Encrypt the userspace provided payload */ 339 rc = enc_payload(snp_dev, seqno, msg_ver, type, req_buf, req_sz); 340 if (rc) 341 return rc; 342 343 /* 344 * Call firmware to process the request. In this function the encrypted 345 * message enters shared memory with the host. So after this call the 346 * sequence number must be incremented or the VMPCK must be deleted to 347 * prevent reuse of the IV. 348 */ 349 rc = snp_issue_guest_request(exit_code, &snp_dev->input, &err); 350 351 /* 352 * If the extended guest request fails due to having too small of a 353 * certificate data buffer, retry the same guest request without the 354 * extended data request in order to increment the sequence number 355 * and thus avoid IV reuse. 356 */ 357 if (exit_code == SVM_VMGEXIT_EXT_GUEST_REQUEST && 358 err == SNP_GUEST_REQ_INVALID_LEN) { 359 const unsigned int certs_npages = snp_dev->input.data_npages; 360 361 exit_code = SVM_VMGEXIT_GUEST_REQUEST; 362 363 /* 364 * If this call to the firmware succeeds, the sequence number can 365 * be incremented allowing for continued use of the VMPCK. If 366 * there is an error reflected in the return value, this value 367 * is checked further down and the result will be the deletion 368 * of the VMPCK and the error code being propagated back to the 369 * user as an ioctl() return code. 370 */ 371 rc = snp_issue_guest_request(exit_code, &snp_dev->input, &err); 372 373 /* 374 * Override the error to inform callers the given extended 375 * request buffer size was too small and give the caller the 376 * required buffer size. 377 */ 378 err = SNP_GUEST_REQ_INVALID_LEN; 379 snp_dev->input.data_npages = certs_npages; 380 } 381 382 if (fw_err) 383 *fw_err = err; 384 385 if (rc) { 386 dev_alert(snp_dev->dev, 387 "Detected error from ASP request. rc: %d, fw_err: %llu\n", 388 rc, *fw_err); 389 goto disable_vmpck; 390 } 391 392 rc = verify_and_dec_payload(snp_dev, resp_buf, resp_sz); 393 if (rc) { 394 dev_alert(snp_dev->dev, 395 "Detected unexpected decode failure from ASP. rc: %d\n", 396 rc); 397 goto disable_vmpck; 398 } 399 400 /* Increment to new message sequence after payload decryption was successful. */ 401 snp_inc_msg_seqno(snp_dev); 402 403 return 0; 404 405 disable_vmpck: 406 snp_disable_vmpck(snp_dev); 407 return rc; 408 } 409 410 static int get_report(struct snp_guest_dev *snp_dev, struct snp_guest_request_ioctl *arg) 411 { 412 struct snp_guest_crypto *crypto = snp_dev->crypto; 413 struct snp_report_resp *resp; 414 struct snp_report_req req; 415 int rc, resp_len; 416 417 lockdep_assert_held(&snp_cmd_mutex); 418 419 if (!arg->req_data || !arg->resp_data) 420 return -EINVAL; 421 422 if (copy_from_user(&req, (void __user *)arg->req_data, sizeof(req))) 423 return -EFAULT; 424 425 /* 426 * The intermediate response buffer is used while decrypting the 427 * response payload. Make sure that it has enough space to cover the 428 * authtag. 429 */ 430 resp_len = sizeof(resp->data) + crypto->a_len; 431 resp = kzalloc(resp_len, GFP_KERNEL_ACCOUNT); 432 if (!resp) 433 return -ENOMEM; 434 435 rc = handle_guest_request(snp_dev, SVM_VMGEXIT_GUEST_REQUEST, arg->msg_version, 436 SNP_MSG_REPORT_REQ, &req, sizeof(req), resp->data, 437 resp_len, &arg->fw_err); 438 if (rc) 439 goto e_free; 440 441 if (copy_to_user((void __user *)arg->resp_data, resp, sizeof(*resp))) 442 rc = -EFAULT; 443 444 e_free: 445 kfree(resp); 446 return rc; 447 } 448 449 static int get_derived_key(struct snp_guest_dev *snp_dev, struct snp_guest_request_ioctl *arg) 450 { 451 struct snp_guest_crypto *crypto = snp_dev->crypto; 452 struct snp_derived_key_resp resp = {0}; 453 struct snp_derived_key_req req; 454 int rc, resp_len; 455 /* Response data is 64 bytes and max authsize for GCM is 16 bytes. */ 456 u8 buf[64 + 16]; 457 458 lockdep_assert_held(&snp_cmd_mutex); 459 460 if (!arg->req_data || !arg->resp_data) 461 return -EINVAL; 462 463 /* 464 * The intermediate response buffer is used while decrypting the 465 * response payload. Make sure that it has enough space to cover the 466 * authtag. 467 */ 468 resp_len = sizeof(resp.data) + crypto->a_len; 469 if (sizeof(buf) < resp_len) 470 return -ENOMEM; 471 472 if (copy_from_user(&req, (void __user *)arg->req_data, sizeof(req))) 473 return -EFAULT; 474 475 rc = handle_guest_request(snp_dev, SVM_VMGEXIT_GUEST_REQUEST, arg->msg_version, 476 SNP_MSG_KEY_REQ, &req, sizeof(req), buf, resp_len, 477 &arg->fw_err); 478 if (rc) 479 return rc; 480 481 memcpy(resp.data, buf, sizeof(resp.data)); 482 if (copy_to_user((void __user *)arg->resp_data, &resp, sizeof(resp))) 483 rc = -EFAULT; 484 485 /* The response buffer contains the sensitive data, explicitly clear it. */ 486 memzero_explicit(buf, sizeof(buf)); 487 memzero_explicit(&resp, sizeof(resp)); 488 return rc; 489 } 490 491 static int get_ext_report(struct snp_guest_dev *snp_dev, struct snp_guest_request_ioctl *arg) 492 { 493 struct snp_guest_crypto *crypto = snp_dev->crypto; 494 struct snp_ext_report_req req; 495 struct snp_report_resp *resp; 496 int ret, npages = 0, resp_len; 497 498 lockdep_assert_held(&snp_cmd_mutex); 499 500 if (!arg->req_data || !arg->resp_data) 501 return -EINVAL; 502 503 if (copy_from_user(&req, (void __user *)arg->req_data, sizeof(req))) 504 return -EFAULT; 505 506 /* userspace does not want certificate data */ 507 if (!req.certs_len || !req.certs_address) 508 goto cmd; 509 510 if (req.certs_len > SEV_FW_BLOB_MAX_SIZE || 511 !IS_ALIGNED(req.certs_len, PAGE_SIZE)) 512 return -EINVAL; 513 514 if (!access_ok((const void __user *)req.certs_address, req.certs_len)) 515 return -EFAULT; 516 517 /* 518 * Initialize the intermediate buffer with all zeros. This buffer 519 * is used in the guest request message to get the certs blob from 520 * the host. If host does not supply any certs in it, then copy 521 * zeros to indicate that certificate data was not provided. 522 */ 523 memset(snp_dev->certs_data, 0, req.certs_len); 524 npages = req.certs_len >> PAGE_SHIFT; 525 cmd: 526 /* 527 * The intermediate response buffer is used while decrypting the 528 * response payload. Make sure that it has enough space to cover the 529 * authtag. 530 */ 531 resp_len = sizeof(resp->data) + crypto->a_len; 532 resp = kzalloc(resp_len, GFP_KERNEL_ACCOUNT); 533 if (!resp) 534 return -ENOMEM; 535 536 snp_dev->input.data_npages = npages; 537 ret = handle_guest_request(snp_dev, SVM_VMGEXIT_EXT_GUEST_REQUEST, arg->msg_version, 538 SNP_MSG_REPORT_REQ, &req.data, 539 sizeof(req.data), resp->data, resp_len, &arg->fw_err); 540 541 /* If certs length is invalid then copy the returned length */ 542 if (arg->fw_err == SNP_GUEST_REQ_INVALID_LEN) { 543 req.certs_len = snp_dev->input.data_npages << PAGE_SHIFT; 544 545 if (copy_to_user((void __user *)arg->req_data, &req, sizeof(req))) 546 ret = -EFAULT; 547 } 548 549 if (ret) 550 goto e_free; 551 552 if (npages && 553 copy_to_user((void __user *)req.certs_address, snp_dev->certs_data, 554 req.certs_len)) { 555 ret = -EFAULT; 556 goto e_free; 557 } 558 559 if (copy_to_user((void __user *)arg->resp_data, resp, sizeof(*resp))) 560 ret = -EFAULT; 561 562 e_free: 563 kfree(resp); 564 return ret; 565 } 566 567 static long snp_guest_ioctl(struct file *file, unsigned int ioctl, unsigned long arg) 568 { 569 struct snp_guest_dev *snp_dev = to_snp_dev(file); 570 void __user *argp = (void __user *)arg; 571 struct snp_guest_request_ioctl input; 572 int ret = -ENOTTY; 573 574 if (copy_from_user(&input, argp, sizeof(input))) 575 return -EFAULT; 576 577 input.fw_err = 0xff; 578 579 /* Message version must be non-zero */ 580 if (!input.msg_version) 581 return -EINVAL; 582 583 mutex_lock(&snp_cmd_mutex); 584 585 /* Check if the VMPCK is not empty */ 586 if (is_vmpck_empty(snp_dev)) { 587 dev_err_ratelimited(snp_dev->dev, "VMPCK is disabled\n"); 588 mutex_unlock(&snp_cmd_mutex); 589 return -ENOTTY; 590 } 591 592 switch (ioctl) { 593 case SNP_GET_REPORT: 594 ret = get_report(snp_dev, &input); 595 break; 596 case SNP_GET_DERIVED_KEY: 597 ret = get_derived_key(snp_dev, &input); 598 break; 599 case SNP_GET_EXT_REPORT: 600 ret = get_ext_report(snp_dev, &input); 601 break; 602 default: 603 break; 604 } 605 606 mutex_unlock(&snp_cmd_mutex); 607 608 if (input.fw_err && copy_to_user(argp, &input, sizeof(input))) 609 return -EFAULT; 610 611 return ret; 612 } 613 614 static void free_shared_pages(void *buf, size_t sz) 615 { 616 unsigned int npages = PAGE_ALIGN(sz) >> PAGE_SHIFT; 617 int ret; 618 619 if (!buf) 620 return; 621 622 ret = set_memory_encrypted((unsigned long)buf, npages); 623 if (ret) { 624 WARN_ONCE(ret, "failed to restore encryption mask (leak it)\n"); 625 return; 626 } 627 628 __free_pages(virt_to_page(buf), get_order(sz)); 629 } 630 631 static void *alloc_shared_pages(struct device *dev, size_t sz) 632 { 633 unsigned int npages = PAGE_ALIGN(sz) >> PAGE_SHIFT; 634 struct page *page; 635 int ret; 636 637 page = alloc_pages(GFP_KERNEL_ACCOUNT, get_order(sz)); 638 if (!page) 639 return NULL; 640 641 ret = set_memory_decrypted((unsigned long)page_address(page), npages); 642 if (ret) { 643 dev_err(dev, "failed to mark page shared, ret=%d\n", ret); 644 __free_pages(page, get_order(sz)); 645 return NULL; 646 } 647 648 return page_address(page); 649 } 650 651 static const struct file_operations snp_guest_fops = { 652 .owner = THIS_MODULE, 653 .unlocked_ioctl = snp_guest_ioctl, 654 }; 655 656 static u8 *get_vmpck(int id, struct snp_secrets_page_layout *layout, u32 **seqno) 657 { 658 u8 *key = NULL; 659 660 switch (id) { 661 case 0: 662 *seqno = &layout->os_area.msg_seqno_0; 663 key = layout->vmpck0; 664 break; 665 case 1: 666 *seqno = &layout->os_area.msg_seqno_1; 667 key = layout->vmpck1; 668 break; 669 case 2: 670 *seqno = &layout->os_area.msg_seqno_2; 671 key = layout->vmpck2; 672 break; 673 case 3: 674 *seqno = &layout->os_area.msg_seqno_3; 675 key = layout->vmpck3; 676 break; 677 default: 678 break; 679 } 680 681 return key; 682 } 683 684 static int __init sev_guest_probe(struct platform_device *pdev) 685 { 686 struct snp_secrets_page_layout *layout; 687 struct sev_guest_platform_data *data; 688 struct device *dev = &pdev->dev; 689 struct snp_guest_dev *snp_dev; 690 struct miscdevice *misc; 691 void __iomem *mapping; 692 int ret; 693 694 if (!dev->platform_data) 695 return -ENODEV; 696 697 data = (struct sev_guest_platform_data *)dev->platform_data; 698 mapping = ioremap_encrypted(data->secrets_gpa, PAGE_SIZE); 699 if (!mapping) 700 return -ENODEV; 701 702 layout = (__force void *)mapping; 703 704 ret = -ENOMEM; 705 snp_dev = devm_kzalloc(&pdev->dev, sizeof(struct snp_guest_dev), GFP_KERNEL); 706 if (!snp_dev) 707 goto e_unmap; 708 709 ret = -EINVAL; 710 snp_dev->vmpck = get_vmpck(vmpck_id, layout, &snp_dev->os_area_msg_seqno); 711 if (!snp_dev->vmpck) { 712 dev_err(dev, "invalid vmpck id %d\n", vmpck_id); 713 goto e_unmap; 714 } 715 716 /* Verify that VMPCK is not zero. */ 717 if (is_vmpck_empty(snp_dev)) { 718 dev_err(dev, "vmpck id %d is null\n", vmpck_id); 719 goto e_unmap; 720 } 721 722 platform_set_drvdata(pdev, snp_dev); 723 snp_dev->dev = dev; 724 snp_dev->layout = layout; 725 726 /* Allocate the shared page used for the request and response message. */ 727 snp_dev->request = alloc_shared_pages(dev, sizeof(struct snp_guest_msg)); 728 if (!snp_dev->request) 729 goto e_unmap; 730 731 snp_dev->response = alloc_shared_pages(dev, sizeof(struct snp_guest_msg)); 732 if (!snp_dev->response) 733 goto e_free_request; 734 735 snp_dev->certs_data = alloc_shared_pages(dev, SEV_FW_BLOB_MAX_SIZE); 736 if (!snp_dev->certs_data) 737 goto e_free_response; 738 739 ret = -EIO; 740 snp_dev->crypto = init_crypto(snp_dev, snp_dev->vmpck, VMPCK_KEY_LEN); 741 if (!snp_dev->crypto) 742 goto e_free_cert_data; 743 744 misc = &snp_dev->misc; 745 misc->minor = MISC_DYNAMIC_MINOR; 746 misc->name = DEVICE_NAME; 747 misc->fops = &snp_guest_fops; 748 749 /* initial the input address for guest request */ 750 snp_dev->input.req_gpa = __pa(snp_dev->request); 751 snp_dev->input.resp_gpa = __pa(snp_dev->response); 752 snp_dev->input.data_gpa = __pa(snp_dev->certs_data); 753 754 ret = misc_register(misc); 755 if (ret) 756 goto e_free_cert_data; 757 758 dev_info(dev, "Initialized SEV guest driver (using vmpck_id %d)\n", vmpck_id); 759 return 0; 760 761 e_free_cert_data: 762 free_shared_pages(snp_dev->certs_data, SEV_FW_BLOB_MAX_SIZE); 763 e_free_response: 764 free_shared_pages(snp_dev->response, sizeof(struct snp_guest_msg)); 765 e_free_request: 766 free_shared_pages(snp_dev->request, sizeof(struct snp_guest_msg)); 767 e_unmap: 768 iounmap(mapping); 769 return ret; 770 } 771 772 static int __exit sev_guest_remove(struct platform_device *pdev) 773 { 774 struct snp_guest_dev *snp_dev = platform_get_drvdata(pdev); 775 776 free_shared_pages(snp_dev->certs_data, SEV_FW_BLOB_MAX_SIZE); 777 free_shared_pages(snp_dev->response, sizeof(struct snp_guest_msg)); 778 free_shared_pages(snp_dev->request, sizeof(struct snp_guest_msg)); 779 deinit_crypto(snp_dev->crypto); 780 misc_deregister(&snp_dev->misc); 781 782 return 0; 783 } 784 785 /* 786 * This driver is meant to be a common SEV guest interface driver and to 787 * support any SEV guest API. As such, even though it has been introduced 788 * with the SEV-SNP support, it is named "sev-guest". 789 */ 790 static struct platform_driver sev_guest_driver = { 791 .remove = __exit_p(sev_guest_remove), 792 .driver = { 793 .name = "sev-guest", 794 }, 795 }; 796 797 module_platform_driver_probe(sev_guest_driver, sev_guest_probe); 798 799 MODULE_AUTHOR("Brijesh Singh <brijesh.singh@amd.com>"); 800 MODULE_LICENSE("GPL"); 801 MODULE_VERSION("1.0.0"); 802 MODULE_DESCRIPTION("AMD SEV Guest Driver"); 803