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virt: sev-guest: Consolidate SNP guest messaging parameters to a struct

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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
This commit is contained in:
Nikunj A Dadhania 2024-10-09 14:58:35 +05:30 • committed by Borislav Petkov (AMD)
parent 6068754a4f
commit 999d73686b
3 changed files with 76 additions and 36 deletions
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9
arch/x86/coco/sev/core.c
View file

@ -2373,7 +2373,8 @@ int snp_issue_svsm_attest_req(u64 call_id, struct svsm_call *call,
}
EXPORT_SYMBOL_GPL(snp_issue_svsm_attest_req);
int snp_issue_guest_request(u64 exit_code, struct snp_req_data *input, struct snp_guest_request_ioctl *rio)
int snp_issue_guest_request(struct snp_guest_req *req, struct snp_req_data *input,
struct snp_guest_request_ioctl *rio)
{
struct ghcb_state state;
struct es_em_ctxt ctxt;
@ -2397,12 +2398,12 @@ int snp_issue_guest_request(u64 exit_code, struct snp_req_data *input, struct sn
vc_ghcb_invalidate(ghcb);
if (exit_code == SVM_VMGEXIT_EXT_GUEST_REQUEST) {
if (req->exit_code == SVM_VMGEXIT_EXT_GUEST_REQUEST) {
ghcb_set_rax(ghcb, input->data_gpa);
ghcb_set_rbx(ghcb, input->data_npages);
}
ret = sev_es_ghcb_hv_call(ghcb, &ctxt, exit_code, input->req_gpa, input->resp_gpa);
ret = sev_es_ghcb_hv_call(ghcb, &ctxt, req->exit_code, input->req_gpa, input->resp_gpa);
if (ret)
goto e_put;
@ -2417,7 +2418,7 @@ int snp_issue_guest_request(u64 exit_code, struct snp_req_data *input, struct sn
case SNP_GUEST_VMM_ERR(SNP_GUEST_VMM_ERR_INVALID_LEN):
/* Number of expected pages are returned in RBX */
if (exit_code == SVM_VMGEXIT_EXT_GUEST_REQUEST) {
if (req->exit_code == SVM_VMGEXIT_EXT_GUEST_REQUEST) {
input->data_npages = ghcb_get_rbx(ghcb);
ret = -ENOSPC;
break;

19
arch/x86/include/asm/sev.h
View file

@ -174,6 +174,19 @@ struct sev_guest_platform_data {
u64 secrets_gpa;
};
struct snp_guest_req {
void *req_buf;
size_t req_sz;
void *resp_buf;
size_t resp_sz;
u64 exit_code;
unsigned int vmpck_id;
u8 msg_version;
u8 msg_type;
};
/*
* The secrets page contains 96-bytes of reserved field that can be used by
* 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);
bool snp_init(struct boot_params *bp);
void __noreturn snp_abort(void);
void snp_dmi_setup(void);
int snp_issue_guest_request(u64 exit_code, struct snp_req_data *input, struct snp_guest_request_ioctl *rio);
int snp_issue_guest_request(struct snp_guest_req *req, struct snp_req_data *input,
struct snp_guest_request_ioctl *rio);
int snp_issue_svsm_attest_req(u64 call_id, struct svsm_call *call, struct svsm_attest_call *input);
void snp_accept_memory(phys_addr_t start, phys_addr_t end);
u64 snp_get_unsupported_features(u64 status);
@ -425,7 +439,8 @@ static inline void snp_set_wakeup_secondary_cpu(void) { }
static inline bool snp_init(struct boot_params *bp) { return false; }
static inline void snp_abort(void) { }
static inline void snp_dmi_setup(void) { }
static inline int snp_issue_guest_request(u64 exit_code, struct snp_req_data *input, struct snp_guest_request_ioctl *rio)
static inline int snp_issue_guest_request(struct snp_guest_req *req, struct snp_req_data *input,
struct snp_guest_request_ioctl *rio)
{
return -ENOTTY;
}

84
drivers/virt/coco/sev-guest/sev-guest.c
View file

@ -177,7 +177,7 @@ static struct aesgcm_ctx *snp_init_crypto(u8 *key, size_t keylen)
return ctx;
}
static int verify_and_dec_payload(struct snp_guest_dev *snp_dev, void *payload, u32 sz)
static int verify_and_dec_payload(struct snp_guest_dev *snp_dev, struct snp_guest_req *req)
{
struct snp_guest_msg *resp_msg = &snp_dev->secret_response;
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,
* If the message size is greater than our buffer length then return
* an error.
*/
if (unlikely((resp_msg_hdr->msg_sz + ctx->authsize) > sz))
if (unlikely((resp_msg_hdr->msg_sz + ctx->authsize) > req->resp_sz))
return -EBADMSG;
/* Decrypt the payload */
memcpy(iv, &resp_msg_hdr->msg_seqno, min(sizeof(iv), sizeof(resp_msg_hdr->msg_seqno)));
if (!aesgcm_decrypt(ctx, payload, resp_msg->payload, resp_msg_hdr->msg_sz,
if (!aesgcm_decrypt(ctx, req->resp_buf, resp_msg->payload, resp_msg_hdr->msg_sz,
&resp_msg_hdr->algo, AAD_LEN, iv, resp_msg_hdr->authtag))
return -EBADMSG;
return 0;
}
static int enc_payload(struct snp_guest_dev *snp_dev, u64 seqno, int version, u8 type,
void *payload, size_t sz)
static int enc_payload(struct snp_guest_dev *snp_dev, u64 seqno, struct snp_guest_req *req)
{
struct snp_guest_msg *msg = &snp_dev->secret_request;
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
hdr->algo = SNP_AEAD_AES_256_GCM;
hdr->hdr_version = MSG_HDR_VER;
hdr->hdr_sz = sizeof(*hdr);
hdr->msg_type = type;
hdr->msg_version = version;
hdr->msg_type = req->msg_type;
hdr->msg_version = req->msg_version;
hdr->msg_seqno = seqno;
hdr->msg_vmpck = vmpck_id;
hdr->msg_sz = sz;
hdr->msg_vmpck = req->vmpck_id;
hdr->msg_sz = req->req_sz;
/* Verify the sequence number is non-zero */
if (!hdr->msg_seqno)
@ -244,17 +243,17 @@ static int enc_payload(struct snp_guest_dev *snp_dev, u64 seqno, int version, u8
pr_debug("request [seqno %lld type %d version %d sz %d]\n",
hdr->msg_seqno, hdr->msg_type, hdr->msg_version, hdr->msg_sz);
if (WARN_ON((sz + ctx->authsize) > sizeof(msg->payload)))
if (WARN_ON((req->req_sz + ctx->authsize) > sizeof(msg->payload)))
return -EBADMSG;
memcpy(iv, &hdr->msg_seqno, min(sizeof(iv), sizeof(hdr->msg_seqno)));
aesgcm_encrypt(ctx, msg->payload, payload, sz, &hdr->algo, AAD_LEN,
iv, hdr->authtag);
aesgcm_encrypt(ctx, msg->payload, req->req_buf, req->req_sz, &hdr->algo,
AAD_LEN, iv, hdr->authtag);
return 0;
}
static int __handle_guest_request(struct snp_guest_dev *snp_dev, u64 exit_code,
static int __handle_guest_request(struct snp_guest_dev *snp_dev, struct snp_guest_req *req,
struct snp_guest_request_ioctl *rio)
{
unsigned long req_start = jiffies;
@ -269,7 +268,7 @@ retry_request:
* sequence number must be incremented or the VMPCK must be deleted to
* prevent reuse of the IV.
*/
rc = snp_issue_guest_request(exit_code, &snp_dev->input, rio);
rc = snp_issue_guest_request(req, &snp_dev->input, rio);
switch (rc) {
case -ENOSPC:
/*
@ -280,7 +279,7 @@ retry_request:
* IV reuse.
*/
override_npages = snp_dev->input.data_npages;
exit_code = SVM_VMGEXIT_GUEST_REQUEST;
req->exit_code = SVM_VMGEXIT_GUEST_REQUEST;
/*
* Override the error to inform callers the given extended
@ -340,10 +339,8 @@ retry_request:
return rc;
}
static int handle_guest_request(struct snp_guest_dev *snp_dev, u64 exit_code,
struct snp_guest_request_ioctl *rio, u8 type,
void *req_buf, size_t req_sz, void *resp_buf,
u32 resp_sz)
static int snp_send_guest_request(struct snp_guest_dev *snp_dev, struct snp_guest_req *req,
struct snp_guest_request_ioctl *rio)
{
u64 seqno;
int rc;
@ -357,7 +354,7 @@ static int handle_guest_request(struct snp_guest_dev *snp_dev, u64 exit_code,
memset(snp_dev->response, 0, sizeof(struct snp_guest_msg));
/* Encrypt the userspace provided payload in snp_dev->secret_request. */
rc = enc_payload(snp_dev, seqno, rio->msg_version, type, req_buf, req_sz);
rc = enc_payload(snp_dev, seqno, req);
if (rc)
return rc;
@ -368,7 +365,7 @@ static int handle_guest_request(struct snp_guest_dev *snp_dev, u64 exit_code,
memcpy(snp_dev->request, &snp_dev->secret_request,
sizeof(snp_dev->secret_request));
rc = __handle_guest_request(snp_dev, exit_code, rio);
rc = __handle_guest_request(snp_dev, req, rio);
if (rc) {
if (rc == -EIO &&
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,
return rc;
}
rc = verify_and_dec_payload(snp_dev, resp_buf, resp_sz);
rc = verify_and_dec_payload(snp_dev, req);
if (rc) {
dev_alert(snp_dev->dev, "Detected unexpected decode failure from ASP. rc: %d\n", rc);
snp_disable_vmpck(snp_dev);
@ -401,6 +398,7 @@ static int get_report(struct snp_guest_dev *snp_dev, struct snp_guest_request_io
{
struct snp_report_req *report_req = &snp_dev->req.report;
struct snp_report_resp *report_resp;
struct snp_guest_req req = {};
int rc, resp_len;
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
if (!report_resp)
return -ENOMEM;
rc = handle_guest_request(snp_dev, SVM_VMGEXIT_GUEST_REQUEST, arg, SNP_MSG_REPORT_REQ,
report_req, sizeof(*report_req), report_resp->data, resp_len);
req.msg_version = arg->msg_version;
req.msg_type = SNP_MSG_REPORT_REQ;
req.vmpck_id = vmpck_id;
req.req_buf = report_req;
req.req_sz = sizeof(*report_req);
req.resp_buf = report_resp->data;
req.resp_sz = resp_len;
req.exit_code = SVM_VMGEXIT_GUEST_REQUEST;
rc = snp_send_guest_request(snp_dev, &req, arg);
if (rc)
goto e_free;
@ -438,6 +444,7 @@ static int get_derived_key(struct snp_guest_dev *snp_dev, struct snp_guest_reque
{
struct snp_derived_key_req *derived_key_req = &snp_dev->req.derived_key;
struct snp_derived_key_resp derived_key_resp = {0};
struct snp_guest_req req = {};
int rc, resp_len;
/* Response data is 64 bytes and max authsize for GCM is 16 bytes. */
u8 buf[64 + 16];
@ -460,8 +467,16 @@ static int get_derived_key(struct snp_guest_dev *snp_dev, struct snp_guest_reque
sizeof(*derived_key_req)))
return -EFAULT;
rc = handle_guest_request(snp_dev, SVM_VMGEXIT_GUEST_REQUEST, arg, SNP_MSG_KEY_REQ,
derived_key_req, sizeof(*derived_key_req), buf, resp_len);
req.msg_version = arg->msg_version;
req.msg_type = SNP_MSG_KEY_REQ;
req.vmpck_id = vmpck_id;
req.req_buf = derived_key_req;
req.req_sz = sizeof(*derived_key_req);
req.resp_buf = buf;
req.resp_sz = resp_len;
req.exit_code = SVM_VMGEXIT_GUEST_REQUEST;
rc = snp_send_guest_request(snp_dev, &req, arg);
if (rc)
return rc;
@ -482,6 +497,7 @@ static int get_ext_report(struct snp_guest_dev *snp_dev, struct snp_guest_reques
{
struct snp_ext_report_req *report_req = &snp_dev->req.ext_report;
struct snp_report_resp *report_resp;
struct snp_guest_req req = {};
int ret, npages = 0, resp_len;
sockptr_t certs_address;
@ -529,9 +545,17 @@ cmd:
return -ENOMEM;
snp_dev->input.data_npages = npages;
ret = handle_guest_request(snp_dev, SVM_VMGEXIT_EXT_GUEST_REQUEST, arg, SNP_MSG_REPORT_REQ,
&report_req->data, sizeof(report_req->data),
report_resp->data, resp_len);
req.msg_version = arg->msg_version;
req.msg_type = SNP_MSG_REPORT_REQ;
req.vmpck_id = vmpck_id;
req.req_buf = &report_req->data;
req.req_sz = sizeof(report_req->data);
req.resp_buf = report_resp->data;
req.resp_sz = resp_len;
req.exit_code = SVM_VMGEXIT_EXT_GUEST_REQUEST;
ret = snp_send_guest_request(snp_dev, &req, arg);
/* If certs length is invalid then copy the returned length */
if (arg->vmm_error == SNP_GUEST_VMM_ERR_INVALID_LEN) {
@ -1057,7 +1081,7 @@ static int __init sev_guest_probe(struct platform_device *pdev)
misc->name = DEVICE_NAME;
misc->fops = &snp_guest_fops;
/* initial the input address for guest request */
/* Initialize the input addresses for guest request */
snp_dev->input.req_gpa = __pa(snp_dev->request);
snp_dev->input.resp_gpa = __pa(snp_dev->response);
snp_dev->input.data_gpa = __pa(snp_dev->certs_data);