virt/coco/sev-guest: Carve out the request issuing logic into a helper

commit 0fdb6cc7c89cb5e0cbc45dbdbafb8e3fb92ddc95 upstream.

This makes the code flow a lot easier to follow.

No functional changes.

  [ Tom: touchups. ]

Signed-off-by: Borislav Petkov (AMD) <bp@alien8.de>
Signed-off-by: Tom Lendacky <thomas.lendacky@amd.com>
Signed-off-by: Borislav Petkov (AMD) <bp@alien8.de>
Link: https://lore.kernel.org/r/20230307192449.24732-6-bp@alien8.de
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/drivers/virt/coco/sev-guest/sev-guest.c b/drivers/virt/coco/sev-guest/sev-guest.c
index fbbc0da..675fd0e 100644 (file)
--- a/drivers/virt/coco/sev-guest/sev-guest.c
+++ b/drivers/virt/coco/sev-guest/sev-guest.c
@@ -320,27 +320,12 @@ 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, override_err = 0;
        unsigned int override_npages = 0;
-       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;
-
 retry_request:
        /*
         * Call firmware to process the request. In this function the encrypted
@@ -349,7 +334,6 @@ retry_request:
         * prevent reuse of the IV.
         */
        rc = snp_issue_guest_request(exit_code, &snp_dev->input, &err);
-
        switch (rc) {
        case -ENOSPC:
                /*
@@ -403,7 +387,33 @@ retry_request:
        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) {
+               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);