[PULL 23/37] pc-bios/s390-ccw: Rework zipl_load_segment function

[Eric Farman <farman@linux.ibm.com>]

From: Zhuoying Cai <zycai@linux.ibm.com>

Change zipl_load_segment() to accept explicit blockno and address
parameters instead of ComponentEntry pointer and return segment length.

Modify this function to allow the caller to specify a memory address
where segment data should be loaded into.

seg_len variable is necessary to store the calculated segment length and
is used during signature verification. Return the length on success, or
a negative return code on failure.

Remove static qualifier and add function declaration to bootmap.h to
make it accessible to other modules.

Signed-off-by: Zhuoying Cai <zycai@linux.ibm.com>
Reviewed-by: Thomas Huth <thuth@redhat.com>
Reviewed-by: Collin Walling <walling@linux.ibm.com>
Reviewed-by: Jared Rossi <jrossi@linux.ibm.com>
Link: https://lore.kernel.org/qemu-devel/20260730214624.2328883-22-zycai@linux.ibm.com
Signed-off-by: Eric Farman <farman@linux.ibm.com>
---
 pc-bios/s390-ccw/bootmap.c | 14 ++++++--------
 pc-bios/s390-ccw/bootmap.h | 13 +++++++++++++
 2 files changed, 19 insertions(+), 8 deletions(-)

diff --git a/pc-bios/s390-ccw/bootmap.c b/pc-bios/s390-ccw/bootmap.c
index 21c219ca94..38e98aab68 100644
--- a/pc-bios/s390-ccw/bootmap.c
+++ b/pc-bios/s390-ccw/bootmap.c
@@ -615,19 +615,15 @@ static int ipl_eckd(void)
  * IPL a SCSI disk
  */
 
-static int zipl_load_segment(ComponentEntry *entry)
+int zipl_load_segment(block_number_t blockno, uint64_t address)
 {
     const int max_entries = (MAX_SECTOR_SIZE / sizeof(ScsiBlockPtr));
     ScsiBlockPtr *bprs = (void *)sec;
     const int bprs_size = sizeof(sec);
-    block_number_t blockno;
-    uint64_t address;
     int i;
     char err_msg[] = "zIPL failed to read BPRS at 0xZZZZZZZZZZZZZZZZ";
     char *blk_no = &err_msg[30]; /* where to print blockno in (those ZZs) */
-
-    blockno = entry->data.blockno;
-    address = entry->compdat.load_addr;
+    int seg_len = 0;
 
     debug_print_int("loading segment at block", blockno);
     debug_print_int("addr", address);
@@ -670,10 +666,12 @@ static int zipl_load_segment(ComponentEntry *entry)
                 puts("zIPL load segment failed");
                 return -EIO;
             }
+
+            seg_len += bprs->size * (bprs[i].blockct + 1);
         }
     } while (blockno);
 
-    return 0;
+    return seg_len;
 }
 
 static int zipl_run_normal(ComponentEntry **entry_ptr, const uint8_t *tmp_sec)
@@ -689,7 +687,7 @@ static int zipl_run_normal(ComponentEntry **entry_ptr, const uint8_t *tmp_sec)
             continue;
         }
 
-        if (zipl_load_segment(entry)) {
+        if (zipl_load_segment(entry->data.blockno, entry->compdat.load_addr) < 0) {
             return -1;
         }
 
diff --git a/pc-bios/s390-ccw/bootmap.h b/pc-bios/s390-ccw/bootmap.h
index 95943441d3..40580600b5 100644
--- a/pc-bios/s390-ccw/bootmap.h
+++ b/pc-bios/s390-ccw/bootmap.h
@@ -113,6 +113,19 @@ typedef struct ScsiMbr {
     ScsiBlockPtr pt;   /* block pointer to program table */
 } __attribute__ ((packed)) ScsiMbr;
 
+/**
+ * zipl_load_segment
+ * @blockno: block number of the first BPRS describing the segment.
+ * @address: guest physical address at which to load the segment.
+ *
+ * Walks the BPRS chain starting at @blockno, loading each data block
+ * into guest memory at @address.
+ *
+ * Returns: length of the segment on success,
+ *          negative value on error.
+ */
+int zipl_load_segment(block_number_t blockno, uint64_t address);
+
 #define ZIPL_MAGIC              "zIPL"
 #define ZIPL_MAGIC_EBCDIC       "\xa9\xc9\xd7\xd3"
 #define IPL1_MAGIC "\xc9\xd7\xd3\xf1" /* == "IPL1" in EBCDIC */
-- 
2.55.0