S390: ccw firmware: Add bootmap interpreter

On s390, there is an architected boot map format that we can read to
boot a certain entry off the disk. Implement a simple reader for this
that always boots the first (default) entry.

Signed-off-by: Alexander Graf <agraf@suse.de>

pc-bios/s390-ccw/bootmap.c

@@ -0,0 +1,235 @@
+/*
+ * QEMU S390 bootmap interpreter
+ *
+ * Copyright (c) 2009 Alexander Graf <agraf@suse.de>
+ *
+ * This work is licensed under the terms of the GNU GPL, version 2 or (at
+ * your option) any later version. See the COPYING file in the top-level
+ * directory.
+ */
+
+#include "s390-ccw.h"
+
+// #define DEBUG_FALLBACK
+
+#ifdef DEBUG_FALLBACK
+#define dputs(txt) \
+    do { sclp_print("zipl: " txt); } while (0)
+#else
+#define dputs(fmt, ...) \
+    do { } while (0)
+#endif
+
+struct scsi_blockptr {
+    uint64_t blockno;
+    uint16_t size;
+    uint16_t blockct;
+    uint8_t reserved[4];
+} __attribute__ ((packed));
+
+struct component_entry {
+    struct scsi_blockptr data;
+    uint8_t pad[7];
+    uint8_t component_type;
+    uint64_t load_address;
+} __attribute((packed));
+
+struct component_header {
+    uint8_t magic[4];
+    uint8_t type;
+    uint8_t reserved[27];
+} __attribute((packed));
+
+struct mbr {
+    uint8_t magic[4];
+    uint32_t version_id;
+    uint8_t reserved[8];
+    struct scsi_blockptr blockptr;
+} __attribute__ ((packed));
+
+#define ZIPL_MAGIC			"zIPL"
+
+#define ZIPL_COMP_HEADER_IPL		0x00
+#define ZIPL_COMP_HEADER_DUMP		0x01
+
+#define ZIPL_COMP_ENTRY_LOAD		0x02
+#define ZIPL_COMP_ENTRY_EXEC		0x01
+
+/* Scratch space */
+static uint8_t sec[SECTOR_SIZE] __attribute__((__aligned__(SECTOR_SIZE)));
+
+/* Check for ZIPL magic. Returns 0 if not matched. */
+static int zipl_magic(uint8_t *ptr)
+{
+    uint32_t *p = (void*)ptr;
+    uint32_t *z = (void*)ZIPL_MAGIC;
+
+    if (*p != *z) {
+        debug_print_int("invalid magic", *p);
+        virtio_panic("invalid magic");
+    }
+
+    return 1;
+}
+
+static int zipl_load_segment(struct component_entry *entry)
+{
+    const int max_entries = (SECTOR_SIZE / sizeof(struct scsi_blockptr));
+    struct scsi_blockptr *bprs = (void*)sec;
+    uint64_t blockno;
+    long address;
+    int i;
+
+    blockno = entry->data.blockno;
+    address = entry->load_address;
+
+    debug_print_int("loading segment at block", blockno);
+    debug_print_int("addr", address);
+
+    do {
+        if (virtio_read(blockno, (uint8_t *)bprs)) {
+            debug_print_int("failed reading bprs at", blockno);
+            goto fail;
+        }
+
+        for (i = 0;; i++) {
+            u64 *cur_desc = (void*)&bprs[i];
+
+            blockno = bprs[i].blockno;
+            if (!blockno)
+                break;
+
+            /* we need the updated blockno for the next indirect entry in the
+               chain, but don't want to advance address */
+            if (i == (max_entries - 1))
+                break;
+
+            address = virtio_load_direct(cur_desc[0], cur_desc[1], 0,
+                                         (void*)address);
+            if (address == -1)
+                goto fail;
+        }
+    } while (blockno);
+
+    return 0;
+
+fail:
+    sclp_print("failed loading segment\n");
+    return -1;
+}
+
+/* Run a zipl program */
+static int zipl_run(struct scsi_blockptr *pte)
+{
+    struct component_header *header;
+    struct component_entry *entry;
+    void (*ipl)(void);
+    uint8_t tmp_sec[SECTOR_SIZE];
+
+    virtio_read(pte->blockno, tmp_sec);
+    header = (struct component_header *)tmp_sec;
+
+    if (!zipl_magic(tmp_sec)) {
+        goto fail;
+    }
+
+    if (header->type != ZIPL_COMP_HEADER_IPL) {
+        goto fail;
+    }
+
+    dputs("start loading images\n");
+
+    /* Load image(s) into RAM */
+    entry = (struct component_entry *)(&header[1]);
+    while (entry->component_type == ZIPL_COMP_ENTRY_LOAD) {
+        if (zipl_load_segment(entry) < 0) {
+            goto fail;
+        }
+
+        entry++;
+
+        if ((uint8_t*)(&entry[1]) > (tmp_sec + SECTOR_SIZE)) {
+            goto fail;
+        }
+    }
+
+    if (entry->component_type != ZIPL_COMP_ENTRY_EXEC) {
+        goto fail;
+    }
+
+    /* Ensure the guest output starts fresh */
+    sclp_print("\n");
+
+    /* And run the OS! */
+    ipl = (void*)(entry->load_address & 0x7fffffff);
+    debug_print_addr("set IPL addr to", ipl);
+    /* should not return */
+    ipl();
+
+    return 0;
+
+fail:
+    sclp_print("failed running zipl\n");
+    return -1;
+}
+
+int zipl_load(void)
+{
+    struct mbr *mbr = (void*)sec;
+    uint8_t *ns, *ns_end;
+    int program_table_entries = 0;
+    int pte_len = sizeof(struct scsi_blockptr);
+    struct scsi_blockptr *prog_table_entry;
+    const char *error = "";
+
+    /* Grab the MBR */
+    virtio_read(0, (void*)mbr);
+
+    dputs("checking magic\n");
+
+    if (!zipl_magic(mbr->magic)) {
+        error = "zipl_magic 1";
+        goto fail;
+    }
+
+    debug_print_int("program table", mbr->blockptr.blockno);
+
+    /* Parse the program table */
+    if (virtio_read(mbr->blockptr.blockno, sec)) {
+        error = "virtio_read";
+        goto fail;
+    }
+
+    if (!zipl_magic(sec)) {
+        error = "zipl_magic 2";
+        goto fail;
+    }
+
+    ns_end = sec + SECTOR_SIZE;
+    for (ns = (sec + pte_len); (ns + pte_len) < ns_end; ns++) {
+        prog_table_entry = (struct scsi_blockptr *)ns;
+        if (!prog_table_entry->blockno) {
+            break;
+        }
+
+        program_table_entries++;
+    }
+
+    debug_print_int("program table entries", program_table_entries);
+
+    if (!program_table_entries) {
+        goto fail;
+    }
+
+    /* Run the default entry */
+
+    prog_table_entry = (struct scsi_blockptr *)(sec + pte_len);
+
+    return zipl_run(prog_table_entry);
+
+fail:
+    sclp_print("failed loading zipl: ");
+    sclp_print(error);
+    sclp_print("\n");
+    return -1;
+}