diff options
Diffstat (limited to 'drivers/virt/coco/sev-guest/sev-guest.c')
| -rw-r--r-- | drivers/virt/coco/sev-guest/sev-guest.c | 128 |
1 files changed, 78 insertions, 50 deletions
diff --git a/drivers/virt/coco/sev-guest/sev-guest.c b/drivers/virt/coco/sev-guest/sev-guest.c index 7b4e9009f335..46f1a8d558b0 100644 --- a/drivers/virt/coco/sev-guest/sev-guest.c +++ b/drivers/virt/coco/sev-guest/sev-guest.c @@ -31,6 +31,9 @@ #define AAD_LEN 48 #define MSG_HDR_VER 1 +#define SNP_REQ_MAX_RETRY_DURATION (60*HZ) +#define SNP_REQ_RETRY_DELAY (2*HZ) + struct snp_guest_crypto { struct crypto_aead *tfm; u8 *iv, *authtag; @@ -318,26 +321,14 @@ static int enc_payload(struct snp_guest_dev *snp_dev, u64 seqno, int version, u8 return __enc_payload(snp_dev, req, payload, sz); } -static int handle_guest_request(struct snp_guest_dev *snp_dev, u64 exit_code, int msg_ver, - u8 type, void *req_buf, size_t req_sz, void *resp_buf, - u32 resp_sz, __u64 *fw_err) +static int __handle_guest_request(struct snp_guest_dev *snp_dev, u64 exit_code, __u64 *fw_err) { - unsigned long err; - u64 seqno; + unsigned long err = 0xff, override_err = 0; + unsigned long req_start = jiffies; + unsigned int override_npages = 0; int rc; - /* Get message sequence and verify that its a non-zero */ - seqno = snp_get_msg_seqno(snp_dev); - if (!seqno) - return -EIO; - - memset(snp_dev->response, 0, sizeof(struct snp_guest_msg)); - - /* Encrypt the userspace provided payload */ - rc = enc_payload(snp_dev, seqno, msg_ver, type, req_buf, req_sz); - if (rc) - return rc; - +retry_request: /* * Call firmware to process the request. In this function the encrypted * message enters shared memory with the host. So after this call the @@ -345,18 +336,24 @@ static int handle_guest_request(struct snp_guest_dev *snp_dev, u64 exit_code, in * prevent reuse of the IV. */ rc = snp_issue_guest_request(exit_code, &snp_dev->input, &err); + switch (rc) { + case -ENOSPC: + /* + * If the extended guest request fails due to having too + * small of a certificate data buffer, retry the same + * guest request without the extended data request in + * order to increment the sequence number and thus avoid + * IV reuse. + */ + override_npages = snp_dev->input.data_npages; + exit_code = SVM_VMGEXIT_GUEST_REQUEST; - /* - * If the extended guest request fails due to having too small of a - * certificate data buffer, retry the same guest request without the - * extended data request in order to increment the sequence number - * and thus avoid IV reuse. - */ - if (exit_code == SVM_VMGEXIT_EXT_GUEST_REQUEST && - err == SNP_GUEST_REQ_INVALID_LEN) { - const unsigned int certs_npages = snp_dev->input.data_npages; - - exit_code = SVM_VMGEXIT_GUEST_REQUEST; + /* + * Override the error to inform callers the given extended + * request buffer size was too small and give the caller the + * required buffer size. + */ + override_err = SNP_GUEST_REQ_INVALID_LEN; /* * If this call to the firmware succeeds, the sequence number can @@ -366,15 +363,20 @@ static int handle_guest_request(struct snp_guest_dev *snp_dev, u64 exit_code, in * of the VMPCK and the error code being propagated back to the * user as an ioctl() return code. */ - rc = snp_issue_guest_request(exit_code, &snp_dev->input, &err); + goto retry_request; - /* - * Override the error to inform callers the given extended - * request buffer size was too small and give the caller the - * required buffer size. - */ - err = SNP_GUEST_REQ_INVALID_LEN; - snp_dev->input.data_npages = certs_npages; + /* + * The host may return SNP_GUEST_REQ_ERR_EBUSY if the request has been + * throttled. Retry in the driver to avoid returning and reusing the + * message sequence number on a different message. + */ + case -EAGAIN: + if (jiffies - req_start > SNP_REQ_MAX_RETRY_DURATION) { + rc = -ETIMEDOUT; + break; + } + schedule_timeout_killable(SNP_REQ_RETRY_DELAY); + goto retry_request; } /* @@ -386,7 +388,10 @@ static int handle_guest_request(struct snp_guest_dev *snp_dev, u64 exit_code, in snp_inc_msg_seqno(snp_dev); if (fw_err) - *fw_err = err; + *fw_err = override_err ?: err; + + if (override_npages) + snp_dev->input.data_npages = override_npages; /* * If an extended guest request was issued and the supplied certificate @@ -394,29 +399,49 @@ static int handle_guest_request(struct snp_guest_dev *snp_dev, u64 exit_code, in * prevent IV reuse. If the standard request was successful, return -EIO * back to the caller as would have originally been returned. */ - if (!rc && err == SNP_GUEST_REQ_INVALID_LEN) + if (!rc && override_err == SNP_GUEST_REQ_INVALID_LEN) + return -EIO; + + return rc; +} + +static int handle_guest_request(struct snp_guest_dev *snp_dev, u64 exit_code, int msg_ver, + u8 type, void *req_buf, size_t req_sz, void *resp_buf, + u32 resp_sz, __u64 *fw_err) +{ + u64 seqno; + int rc; + + /* Get message sequence and verify that its a non-zero */ + seqno = snp_get_msg_seqno(snp_dev); + if (!seqno) return -EIO; + memset(snp_dev->response, 0, sizeof(struct snp_guest_msg)); + + /* Encrypt the userspace provided payload */ + rc = enc_payload(snp_dev, seqno, msg_ver, type, req_buf, req_sz); + if (rc) + return rc; + + rc = __handle_guest_request(snp_dev, exit_code, fw_err); if (rc) { - dev_alert(snp_dev->dev, - "Detected error from ASP request. rc: %d, fw_err: %llu\n", - rc, *fw_err); - goto disable_vmpck; + if (rc == -EIO && *fw_err == SNP_GUEST_REQ_INVALID_LEN) + return rc; + + dev_alert(snp_dev->dev, "Detected error from ASP request. rc: %d, fw_err: %llu\n", rc, *fw_err); + snp_disable_vmpck(snp_dev); + return rc; } rc = verify_and_dec_payload(snp_dev, resp_buf, resp_sz); if (rc) { - dev_alert(snp_dev->dev, - "Detected unexpected decode failure from ASP. rc: %d\n", - rc); - goto disable_vmpck; + dev_alert(snp_dev->dev, "Detected unexpected decode failure from ASP. rc: %d\n", rc); + snp_disable_vmpck(snp_dev); + return rc; } return 0; - -disable_vmpck: - snp_disable_vmpck(snp_dev); - return rc; } static int get_report(struct snp_guest_dev *snp_dev, struct snp_guest_request_ioctl *arg) @@ -703,6 +728,9 @@ static int __init sev_guest_probe(struct platform_device *pdev) void __iomem *mapping; int ret; + if (!cc_platform_has(CC_ATTR_GUEST_SEV_SNP)) + return -ENODEV; + if (!dev->platform_data) return -ENODEV; |