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virt: sev-guest: Consolidate SNP guest messaging parameters to a struct
Add a snp_guest_req structure to eliminate the need to pass a long list of parameters. This structure will be used to call the SNP Guest message request API, simplifying the function arguments. Update the snp_issue_guest_request() prototype to include the new guest request structure. Signed-off-by: Nikunj A Dadhania <nikunj@amd.com> Signed-off-by: Borislav Petkov (AMD) <bp@alien8.de> Reviewed-by: Tom Lendacky <thomas.lendacky@amd.com> Link: https://lore.kernel.org/r/20241009092850.197575-5-nikunj@amd.com
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3 files changed

+76
-36
lines changed

3 files changed

+76
-36
lines changed

‎arch/x86/coco/sev/core.c‎

Lines changed: 5 additions & 4 deletions
Original file line numberDiff line numberDiff line change
@@ -2373,7 +2373,8 @@ int snp_issue_svsm_attest_req(u64 call_id, struct svsm_call *call,
23732373
}
23742374
EXPORT_SYMBOL_GPL(snp_issue_svsm_attest_req);
23752375

2376-
int snp_issue_guest_request(u64 exit_code, struct snp_req_data *input, struct snp_guest_request_ioctl *rio)
2376+
int snp_issue_guest_request(struct snp_guest_req *req, struct snp_req_data *input,
2377+
struct snp_guest_request_ioctl *rio)
23772378
{
23782379
struct ghcb_state state;
23792380
struct es_em_ctxt ctxt;
@@ -2397,12 +2398,12 @@ int snp_issue_guest_request(u64 exit_code, struct snp_req_data *input, struct sn
23972398

23982399
vc_ghcb_invalidate(ghcb);
23992400

2400-
if (exit_code == SVM_VMGEXIT_EXT_GUEST_REQUEST) {
2401+
if (req->exit_code == SVM_VMGEXIT_EXT_GUEST_REQUEST) {
24012402
ghcb_set_rax(ghcb, input->data_gpa);
24022403
ghcb_set_rbx(ghcb, input->data_npages);
24032404
}
24042405

2405-
ret = sev_es_ghcb_hv_call(ghcb, &ctxt, exit_code, input->req_gpa, input->resp_gpa);
2406+
ret = sev_es_ghcb_hv_call(ghcb, &ctxt, req->exit_code, input->req_gpa, input->resp_gpa);
24062407
if (ret)
24072408
goto e_put;
24082409

@@ -2417,7 +2418,7 @@ int snp_issue_guest_request(u64 exit_code, struct snp_req_data *input, struct sn
24172418

24182419
case SNP_GUEST_VMM_ERR(SNP_GUEST_VMM_ERR_INVALID_LEN):
24192420
/* Number of expected pages are returned in RBX */
2420-
if (exit_code == SVM_VMGEXIT_EXT_GUEST_REQUEST) {
2421+
if (req->exit_code == SVM_VMGEXIT_EXT_GUEST_REQUEST) {
24212422
input->data_npages = ghcb_get_rbx(ghcb);
24222423
ret = -ENOSPC;
24232424
break;

‎arch/x86/include/asm/sev.h‎

Lines changed: 17 additions & 2 deletions
Original file line numberDiff line numberDiff line change
@@ -174,6 +174,19 @@ struct sev_guest_platform_data {
174174
u64 secrets_gpa;
175175
};
176176

177+
struct snp_guest_req {
178+
void *req_buf;
179+
size_t req_sz;
180+
181+
void *resp_buf;
182+
size_t resp_sz;
183+
184+
u64 exit_code;
185+
unsigned int vmpck_id;
186+
u8 msg_version;
187+
u8 msg_type;
188+
};
189+
177190
/*
178191
* The secrets page contains 96-bytes of reserved field that can be used by
179192
* the guest OS. The guest OS uses the area to save the message sequence
@@ -395,7 +408,8 @@ void snp_set_wakeup_secondary_cpu(void);
395408
bool snp_init(struct boot_params *bp);
396409
void __noreturn snp_abort(void);
397410
void snp_dmi_setup(void);
398-
int snp_issue_guest_request(u64 exit_code, struct snp_req_data *input, struct snp_guest_request_ioctl *rio);
411+
int snp_issue_guest_request(struct snp_guest_req *req, struct snp_req_data *input,
412+
struct snp_guest_request_ioctl *rio);
399413
int snp_issue_svsm_attest_req(u64 call_id, struct svsm_call *call, struct svsm_attest_call *input);
400414
void snp_accept_memory(phys_addr_t start, phys_addr_t end);
401415
u64 snp_get_unsupported_features(u64 status);
@@ -425,7 +439,8 @@ static inline void snp_set_wakeup_secondary_cpu(void) { }
425439
static inline bool snp_init(struct boot_params *bp) { return false; }
426440
static inline void snp_abort(void) { }
427441
static inline void snp_dmi_setup(void) { }
428-
static inline int snp_issue_guest_request(u64 exit_code, struct snp_req_data *input, struct snp_guest_request_ioctl *rio)
442+
static inline int snp_issue_guest_request(struct snp_guest_req *req, struct snp_req_data *input,
443+
struct snp_guest_request_ioctl *rio)
429444
{
430445
return -ENOTTY;
431446
}

‎drivers/virt/coco/sev-guest/sev-guest.c‎

Lines changed: 54 additions & 30 deletions
Original file line numberDiff line numberDiff line change
@@ -177,7 +177,7 @@ static struct aesgcm_ctx *snp_init_crypto(u8 *key, size_t keylen)
177177
return ctx;
178178
}
179179

180-
static int verify_and_dec_payload(struct snp_guest_dev *snp_dev, void *payload, u32 sz)
180+
static int verify_and_dec_payload(struct snp_guest_dev *snp_dev, struct snp_guest_req *req)
181181
{
182182
struct snp_guest_msg *resp_msg = &snp_dev->secret_response;
183183
struct snp_guest_msg *req_msg = &snp_dev->secret_request;
@@ -206,20 +206,19 @@ static int verify_and_dec_payload(struct snp_guest_dev *snp_dev, void *payload,
206206
* If the message size is greater than our buffer length then return
207207
* an error.
208208
*/
209-
if (unlikely((resp_msg_hdr->msg_sz + ctx->authsize) > sz))
209+
if (unlikely((resp_msg_hdr->msg_sz + ctx->authsize) > req->resp_sz))
210210
return -EBADMSG;
211211

212212
/* Decrypt the payload */
213213
memcpy(iv, &resp_msg_hdr->msg_seqno, min(sizeof(iv), sizeof(resp_msg_hdr->msg_seqno)));
214-
if (!aesgcm_decrypt(ctx, payload, resp_msg->payload, resp_msg_hdr->msg_sz,
214+
if (!aesgcm_decrypt(ctx, req->resp_buf, resp_msg->payload, resp_msg_hdr->msg_sz,
215215
&resp_msg_hdr->algo, AAD_LEN, iv, resp_msg_hdr->authtag))
216216
return -EBADMSG;
217217

218218
return 0;
219219
}
220220

221-
static int enc_payload(struct snp_guest_dev *snp_dev, u64 seqno, int version, u8 type,
222-
void *payload, size_t sz)
221+
static int enc_payload(struct snp_guest_dev *snp_dev, u64 seqno, struct snp_guest_req *req)
223222
{
224223
struct snp_guest_msg *msg = &snp_dev->secret_request;
225224
struct snp_guest_msg_hdr *hdr = &msg->hdr;
@@ -231,11 +230,11 @@ static int enc_payload(struct snp_guest_dev *snp_dev, u64 seqno, int version, u8
231230
hdr->algo = SNP_AEAD_AES_256_GCM;
232231
hdr->hdr_version = MSG_HDR_VER;
233232
hdr->hdr_sz = sizeof(*hdr);
234-
hdr->msg_type = type;
235-
hdr->msg_version = version;
233+
hdr->msg_type = req->msg_type;
234+
hdr->msg_version = req->msg_version;
236235
hdr->msg_seqno = seqno;
237-
hdr->msg_vmpck = vmpck_id;
238-
hdr->msg_sz = sz;
236+
hdr->msg_vmpck = req->vmpck_id;
237+
hdr->msg_sz = req->req_sz;
239238

240239
/* Verify the sequence number is non-zero */
241240
if (!hdr->msg_seqno)
@@ -244,17 +243,17 @@ static int enc_payload(struct snp_guest_dev *snp_dev, u64 seqno, int version, u8
244243
pr_debug("request [seqno %lld type %d version %d sz %d]\n",
245244
hdr->msg_seqno, hdr->msg_type, hdr->msg_version, hdr->msg_sz);
246245

247-
if (WARN_ON((sz + ctx->authsize) > sizeof(msg->payload)))
246+
if (WARN_ON((req->req_sz + ctx->authsize) > sizeof(msg->payload)))
248247
return -EBADMSG;
249248

250249
memcpy(iv, &hdr->msg_seqno, min(sizeof(iv), sizeof(hdr->msg_seqno)));
251-
aesgcm_encrypt(ctx, msg->payload, payload, sz, &hdr->algo, AAD_LEN,
252-
iv, hdr->authtag);
250+
aesgcm_encrypt(ctx, msg->payload, req->req_buf, req->req_sz, &hdr->algo,
251+
AAD_LEN, iv, hdr->authtag);
253252

254253
return 0;
255254
}
256255

257-
static int __handle_guest_request(struct snp_guest_dev *snp_dev, u64 exit_code,
256+
static int __handle_guest_request(struct snp_guest_dev *snp_dev, struct snp_guest_req *req,
258257
struct snp_guest_request_ioctl *rio)
259258
{
260259
unsigned long req_start = jiffies;
@@ -269,7 +268,7 @@ static int __handle_guest_request(struct snp_guest_dev *snp_dev, u64 exit_code,
269268
* sequence number must be incremented or the VMPCK must be deleted to
270269
* prevent reuse of the IV.
271270
*/
272-
rc = snp_issue_guest_request(exit_code, &snp_dev->input, rio);
271+
rc = snp_issue_guest_request(req, &snp_dev->input, rio);
273272
switch (rc) {
274273
case -ENOSPC:
275274
/*
@@ -280,7 +279,7 @@ static int __handle_guest_request(struct snp_guest_dev *snp_dev, u64 exit_code,
280279
* IV reuse.
281280
*/
282281
override_npages = snp_dev->input.data_npages;
283-
exit_code = SVM_VMGEXIT_GUEST_REQUEST;
282+
req->exit_code = SVM_VMGEXIT_GUEST_REQUEST;
284283

285284
/*
286285
* Override the error to inform callers the given extended
@@ -340,10 +339,8 @@ static int __handle_guest_request(struct snp_guest_dev *snp_dev, u64 exit_code,
340339
return rc;
341340
}
342341

343-
static int handle_guest_request(struct snp_guest_dev *snp_dev, u64 exit_code,
344-
struct snp_guest_request_ioctl *rio, u8 type,
345-
void *req_buf, size_t req_sz, void *resp_buf,
346-
u32 resp_sz)
342+
static int snp_send_guest_request(struct snp_guest_dev *snp_dev, struct snp_guest_req *req,
343+
struct snp_guest_request_ioctl *rio)
347344
{
348345
u64 seqno;
349346
int rc;
@@ -357,7 +354,7 @@ static int handle_guest_request(struct snp_guest_dev *snp_dev, u64 exit_code,
357354
memset(snp_dev->response, 0, sizeof(struct snp_guest_msg));
358355

359356
/* Encrypt the userspace provided payload in snp_dev->secret_request. */
360-
rc = enc_payload(snp_dev, seqno, rio->msg_version, type, req_buf, req_sz);
357+
rc = enc_payload(snp_dev, seqno, req);
361358
if (rc)
362359
return rc;
363360

@@ -368,7 +365,7 @@ static int handle_guest_request(struct snp_guest_dev *snp_dev, u64 exit_code,
368365
memcpy(snp_dev->request, &snp_dev->secret_request,
369366
sizeof(snp_dev->secret_request));
370367

371-
rc = __handle_guest_request(snp_dev, exit_code, rio);
368+
rc = __handle_guest_request(snp_dev, req, rio);
372369
if (rc) {
373370
if (rc == -EIO &&
374371
rio->exitinfo2 == SNP_GUEST_VMM_ERR(SNP_GUEST_VMM_ERR_INVALID_LEN))
@@ -382,7 +379,7 @@ static int handle_guest_request(struct snp_guest_dev *snp_dev, u64 exit_code,
382379
return rc;
383380
}
384381

385-
rc = verify_and_dec_payload(snp_dev, resp_buf, resp_sz);
382+
rc = verify_and_dec_payload(snp_dev, req);
386383
if (rc) {
387384
dev_alert(snp_dev->dev, "Detected unexpected decode failure from ASP. rc: %d\n", rc);
388385
snp_disable_vmpck(snp_dev);
@@ -401,6 +398,7 @@ static int get_report(struct snp_guest_dev *snp_dev, struct snp_guest_request_io
401398
{
402399
struct snp_report_req *report_req = &snp_dev->req.report;
403400
struct snp_report_resp *report_resp;
401+
struct snp_guest_req req = {};
404402
int rc, resp_len;
405403

406404
lockdep_assert_held(&snp_cmd_mutex);
@@ -421,8 +419,16 @@ static int get_report(struct snp_guest_dev *snp_dev, struct snp_guest_request_io
421419
if (!report_resp)
422420
return -ENOMEM;
423421

424-
rc = handle_guest_request(snp_dev, SVM_VMGEXIT_GUEST_REQUEST, arg, SNP_MSG_REPORT_REQ,
425-
report_req, sizeof(*report_req), report_resp->data, resp_len);
422+
req.msg_version = arg->msg_version;
423+
req.msg_type = SNP_MSG_REPORT_REQ;
424+
req.vmpck_id = vmpck_id;
425+
req.req_buf = report_req;
426+
req.req_sz = sizeof(*report_req);
427+
req.resp_buf = report_resp->data;
428+
req.resp_sz = resp_len;
429+
req.exit_code = SVM_VMGEXIT_GUEST_REQUEST;
430+
431+
rc = snp_send_guest_request(snp_dev, &req, arg);
426432
if (rc)
427433
goto e_free;
428434

@@ -438,6 +444,7 @@ static int get_derived_key(struct snp_guest_dev *snp_dev, struct snp_guest_reque
438444
{
439445
struct snp_derived_key_req *derived_key_req = &snp_dev->req.derived_key;
440446
struct snp_derived_key_resp derived_key_resp = {0};
447+
struct snp_guest_req req = {};
441448
int rc, resp_len;
442449
/* Response data is 64 bytes and max authsize for GCM is 16 bytes. */
443450
u8 buf[64 + 16];
@@ -460,8 +467,16 @@ static int get_derived_key(struct snp_guest_dev *snp_dev, struct snp_guest_reque
460467
sizeof(*derived_key_req)))
461468
return -EFAULT;
462469

463-
rc = handle_guest_request(snp_dev, SVM_VMGEXIT_GUEST_REQUEST, arg, SNP_MSG_KEY_REQ,
464-
derived_key_req, sizeof(*derived_key_req), buf, resp_len);
470+
req.msg_version = arg->msg_version;
471+
req.msg_type = SNP_MSG_KEY_REQ;
472+
req.vmpck_id = vmpck_id;
473+
req.req_buf = derived_key_req;
474+
req.req_sz = sizeof(*derived_key_req);
475+
req.resp_buf = buf;
476+
req.resp_sz = resp_len;
477+
req.exit_code = SVM_VMGEXIT_GUEST_REQUEST;
478+
479+
rc = snp_send_guest_request(snp_dev, &req, arg);
465480
if (rc)
466481
return rc;
467482

@@ -482,6 +497,7 @@ static int get_ext_report(struct snp_guest_dev *snp_dev, struct snp_guest_reques
482497
{
483498
struct snp_ext_report_req *report_req = &snp_dev->req.ext_report;
484499
struct snp_report_resp *report_resp;
500+
struct snp_guest_req req = {};
485501
int ret, npages = 0, resp_len;
486502
sockptr_t certs_address;
487503

@@ -529,9 +545,17 @@ static int get_ext_report(struct snp_guest_dev *snp_dev, struct snp_guest_reques
529545
return -ENOMEM;
530546

531547
snp_dev->input.data_npages = npages;
532-
ret = handle_guest_request(snp_dev, SVM_VMGEXIT_EXT_GUEST_REQUEST, arg, SNP_MSG_REPORT_REQ,
533-
&report_req->data, sizeof(report_req->data),
534-
report_resp->data, resp_len);
548+
549+
req.msg_version = arg->msg_version;
550+
req.msg_type = SNP_MSG_REPORT_REQ;
551+
req.vmpck_id = vmpck_id;
552+
req.req_buf = &report_req->data;
553+
req.req_sz = sizeof(report_req->data);
554+
req.resp_buf = report_resp->data;
555+
req.resp_sz = resp_len;
556+
req.exit_code = SVM_VMGEXIT_EXT_GUEST_REQUEST;
557+
558+
ret = snp_send_guest_request(snp_dev, &req, arg);
535559

536560
/* If certs length is invalid then copy the returned length */
537561
if (arg->vmm_error == SNP_GUEST_VMM_ERR_INVALID_LEN) {
@@ -1057,7 +1081,7 @@ static int __init sev_guest_probe(struct platform_device *pdev)
10571081
misc->name = DEVICE_NAME;
10581082
misc->fops = &snp_guest_fops;
10591083

1060-
/* initial the input address for guest request */
1084+
/* Initialize the input addresses for guest request */
10611085
snp_dev->input.req_gpa = __pa(snp_dev->request);
10621086
snp_dev->input.resp_gpa = __pa(snp_dev->response);
10631087
snp_dev->input.data_gpa = __pa(snp_dev->certs_data);

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