pc-bios/s390-ccw: ISO-9660 El Torito boot implementation

This patch enables boot from media formatted according to
ISO-9660 and El Torito bootable CD specification.

We try to boot from device as ISO-9660 media when SCSI IPL failed.

The first boot catalog entry with bootable flag is used.

ISO-9660 media with default 2048-bytes sector size only is supported.
Signed-off-by: NMaxim Samoylov <max7255@linux.vnet.ibm.com>
Reviewed-by: NDavid Hildenbrand <dahi@linux.vnet.ibm.com>
Signed-off-by: NCornelia Huck <cornelia.huck@de.ibm.com>

pc-bios/s390-ccw/bootmap.c

@@ -444,6 +444,107 @@ static void ipl_scsi(void)
     zipl_run(prog_table_entry); /* no return */
 }
 
+/***********************************************************************
+ * IPL El Torito ISO9660 image or DVD
+ */
+
+static bool is_iso_bc_entry_compatible(IsoBcSection *s)
+{
+    return true;
+}
+
+static void load_iso_bc_entry(IsoBcSection *load)
+{
+    IsoBcSection s = *load;
+    /*
+     * According to spec, extent for each file
+     * is padded and ISO_SECTOR_SIZE bytes aligned
+     */
+    uint32_t blks_to_load = bswap16(s.sector_count) >> ET_SECTOR_SHIFT;
+
+    read_iso_boot_image(bswap32(s.load_rba),
+                        (void *)((uint64_t)bswap16(s.load_segment)),
+                        blks_to_load);
+
+    /* Trying to get PSW at zero address */
+    if (*((uint64_t *)0) & IPL_PSW_MASK) {
+        jump_to_IPL_code((*((uint64_t *)0)) & 0x7fffffff);
+    }
+
+    /* Try default linux start address */
+    jump_to_IPL_code(KERN_IMAGE_START);
+}
+
+static uint32_t find_iso_bc(void)
+{
+    IsoVolDesc *vd = (IsoVolDesc *)sec;
+    uint32_t block_num = ISO_PRIMARY_VD_SECTOR;
+
+    if (virtio_read_many(block_num++, sec, 1)) {
+        /* If primary vd cannot be read, there is no boot catalog */
+        return 0;
+    }
+
+    while (is_iso_vd_valid(vd) && vd->type != VOL_DESC_TERMINATOR) {
+        if (vd->type == VOL_DESC_TYPE_BOOT) {
+            IsoVdElTorito *et = &vd->vd.boot;
+
+            if (!_memcmp(&et->el_torito[0], el_torito_magic, 32)) {
+                return bswap32(et->bc_offset);
+            }
+        }
+        read_iso_sector(block_num++, sec,
+                        "Failed to read ISO volume descriptor");
+    }
+
+    return 0;
+}
+
+static IsoBcSection *find_iso_bc_entry(void)
+{
+    IsoBcEntry *e = (IsoBcEntry *)sec;
+    uint32_t offset = find_iso_bc();
+    int i;
+
+    if (!offset) {
+        return NULL;
+    }
+
+    read_iso_sector(offset, sec, "Failed to read El Torito boot catalog");
+
+    if (!is_iso_bc_valid(e)) {
+        /* The validation entry is mandatory */
+        virtio_panic("No valid boot catalog found!\n");
+        return NULL;
+    }
+
+    /*
+     * Each entry has 32 bytes size, so one sector cannot contain > 64 entries.
+     * We consider only boot catalogs with no more than 64 entries.
+     */
+    for (i = 1; i < ISO_BC_ENTRY_PER_SECTOR; i++) {
+        if (e[i].id == ISO_BC_BOOTABLE_SECTION) {
+            if (is_iso_bc_entry_compatible(&e[i].body.sect)) {
+                return &e[i].body.sect;
+            }
+        }
+    }
+
+    virtio_panic("No suitable boot entry found on ISO-9660 media!\n");
+
+    return NULL;
+}
+
+static void ipl_iso_el_torito(void)
+{
+    IsoBcSection *s = find_iso_bc_entry();
+
+    if (s) {
+        load_iso_bc_entry(s);
+        /* no return */
+    }
+}
+
 /***********************************************************************
  * IPL starts here
  */
@@ -463,6 +564,12 @@ void zipl_load(void)
         ipl_scsi(); /* no return */
     }
 
+    /* Check if we can boot as ISO media */
+    if (virtio_guessed_disk_nature()) {
+        virtio_assume_iso9660();
+    }
+    ipl_iso_el_torito();
+
     /* We have failed to follow the SCSI scheme, so */
     if (virtio_guessed_disk_nature()) {
         sclp_print("Using guessed DASD geometry.\n");

pc-bios/s390-ccw/bootmap.h

@@ -341,4 +341,195 @@ static inline bool magic_match(const void *data, const void *magic)
     return *((uint32_t *)data) == *((uint32_t *)magic);
 }
 
+static inline int _memcmp(const void *s1, const void *s2, size_t n)
+{
+    int i;
+    const uint8_t *p1 = s1, *p2 = s2;
+
+    for (i = 0; i < n; i++) {
+        if (p1[i] != p2[i]) {
+            return p1[i] > p2[i] ? 1 : -1;
+        }
+    }
+
+    return 0;
+}
+
+/* from include/qemu/bswap.h */
+
+/* El Torito is always little-endian */
+static inline uint16_t bswap16(uint16_t x)
+{
+    return ((x & 0x00ff) << 8) | ((x & 0xff00) >> 8);
+}
+
+static inline uint32_t bswap32(uint32_t x)
+{
+    return ((x & 0x000000ffU) << 24) | ((x & 0x0000ff00U) <<  8) |
+           ((x & 0x00ff0000U) >>  8) | ((x & 0xff000000U) >> 24);
+}
+
+static inline uint64_t bswap64(uint64_t x)
+{
+    return ((x & 0x00000000000000ffULL) << 56) |
+           ((x & 0x000000000000ff00ULL) << 40) |
+           ((x & 0x0000000000ff0000ULL) << 24) |
+           ((x & 0x00000000ff000000ULL) <<  8) |
+           ((x & 0x000000ff00000000ULL) >>  8) |
+           ((x & 0x0000ff0000000000ULL) >> 24) |
+           ((x & 0x00ff000000000000ULL) >> 40) |
+           ((x & 0xff00000000000000ULL) >> 56);
+}
+
+#define ISO_SECTOR_SIZE 2048
+/* El Torito specifies boot image size in 512 byte blocks */
+#define ET_SECTOR_SHIFT 2
+#define KERN_IMAGE_START 0x010000UL
+#define PSW_MASK_64 0x0000000100000000ULL
+#define PSW_MASK_32 0x0000000080000000ULL
+#define IPL_PSW_MASK (PSW_MASK_32 | PSW_MASK_64)
+
+#define ISO_PRIMARY_VD_SECTOR 16
+
+static inline void read_iso_sector(uint32_t block_offset, void *buf,
+                                   const char *errmsg)
+{
+    IPL_assert(virtio_read_many(block_offset, buf, 1) == 0, errmsg);
+}
+
+static inline void read_iso_boot_image(uint32_t block_offset, void *load_addr,
+                                       uint32_t blks_to_load)
+{
+    IPL_assert(virtio_read_many(block_offset, load_addr, blks_to_load) == 0,
+               "Failed to read boot image!");
+}
+
+const uint8_t el_torito_magic[] = "EL TORITO SPECIFICATION"
+                                  "\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0";
+
+typedef struct IsoDirHdr {
+    uint8_t dr_len;
+    uint8_t ear_len;
+    uint64_t ext_loc;
+    uint64_t data_len;
+    uint8_t recording_datetime[7];
+    uint8_t file_flags;
+    uint8_t file_unit_size;
+    uint8_t gap_size;
+    uint32_t vol_seqnum;
+    uint8_t fileid_len;
+} __attribute__((packed)) IsoDirHdr;
+
+typedef struct IsoVdElTorito {
+    uint8_t el_torito[32]; /* must contain el_torito_magic value */
+    uint8_t unused0[32];
+    uint32_t bc_offset;
+    uint8_t unused1[1974];
+} __attribute__((packed)) IsoVdElTorito;
+
+typedef struct IsoVdPrimary {
+    uint8_t unused1;
+    uint8_t sys_id[32];
+    uint8_t vol_id[32];
+    uint8_t unused2[8];
+    uint64_t vol_space_size;
+    uint8_t unused3[32];
+    uint32_t vol_set_size;
+    uint32_t vol_seqnum;
+    uint32_t log_block_size;
+    uint64_t path_table_size;
+    uint32_t l_path_table;
+    uint32_t opt_l_path_table;
+    uint32_t m_path_table;
+    uint32_t opt_m_path_table;
+    IsoDirHdr rootdir;
+    uint8_t root_null;
+    uint8_t reserved2[1858];
+} __attribute__((packed)) IsoVdPrimary;
+
+typedef struct IsoVolDesc {
+    uint8_t type;
+    uint8_t ident[5];
+    uint8_t version;
+    union {
+        IsoVdElTorito boot;
+        IsoVdPrimary primary;
+    } vd;
+} __attribute__((packed)) IsoVolDesc;
+
+const uint8_t vol_desc_magic[] = "CD001";
+#define VOL_DESC_TYPE_BOOT 0
+#define VOL_DESC_TYPE_PRIMARY 1
+#define VOL_DESC_TYPE_SUPPLEMENT 2
+#define VOL_DESC_TYPE_PARTITION 3
+#define VOL_DESC_TERMINATOR 255
+
+static inline bool is_iso_vd_valid(IsoVolDesc *vd)
+{
+    return !_memcmp(&vd->ident[0], vol_desc_magic, 5) &&
+           vd->version == 0x1 &&
+           vd->type <= VOL_DESC_TYPE_PARTITION;
+}
+
+typedef struct IsoBcValid {
+    uint8_t platform_id;
+    uint16_t reserved;
+    uint8_t id[24];
+    uint16_t checksum;
+    uint8_t key[2];
+} __attribute__((packed)) IsoBcValid;
+
+typedef struct IsoBcSection {
+    uint8_t boot_type;
+    uint16_t load_segment;
+    uint8_t sys_type;
+    uint8_t unused;
+    uint16_t sector_count;
+    uint32_t load_rba;
+    uint8_t selection[20];
+} __attribute__((packed)) IsoBcSection;
+
+typedef struct IsoBcHdr {
+    uint8_t platform_id;
+    uint16_t sect_num;
+    uint8_t id[28];
+} __attribute__((packed)) IsoBcHdr;
+
+typedef struct IsoBcEntry {
+    uint8_t id;
+    union {
+        IsoBcValid valid; /* id == 0x01 */
+        IsoBcSection sect; /* id == 0x88 || id == 0x0 */
+        IsoBcHdr hdr; /* id == 0x90 || id == 0x91 */
+    } body;
+} __attribute__((packed)) IsoBcEntry;
+
+#define ISO_BC_ENTRY_PER_SECTOR (ISO_SECTOR_SIZE / sizeof(IsoBcEntry))
+#define ISO_BC_HDR_VALIDATION 0x01
+#define ISO_BC_BOOTABLE_SECTION 0x88
+#define ISO_BC_MAGIC_55 0x55
+#define ISO_BC_MAGIC_AA 0xaa
+#define ISO_BC_PLATFORM_X86 0x0
+#define ISO_BC_PLATFORM_PPC 0x1
+#define ISO_BC_PLATFORM_MAC 0x2
+
+static inline bool is_iso_bc_valid(IsoBcEntry *e)
+{
+    IsoBcValid *v = &e->body.valid;
+
+    if (e->id != ISO_BC_HDR_VALIDATION) {
+        return false;
+    }
+
+    if (v->platform_id != ISO_BC_PLATFORM_X86 &&
+        v->platform_id != ISO_BC_PLATFORM_PPC &&
+        v->platform_id != ISO_BC_PLATFORM_MAC) {
+        return false;
+    }
+
+    return v->key[0] == ISO_BC_MAGIC_55 &&
+           v->key[1] == ISO_BC_MAGIC_AA &&
+           v->reserved == 0x0;
+}
+
 #endif /* _PC_BIOS_S390_CCW_BOOTMAP_H */

pc-bios/s390-ccw/virtio.c

@@ -278,6 +278,13 @@ void virtio_assume_scsi(void)
     blk_cfg.physical_block_exp = 0;
 }
 
+void virtio_assume_iso9660(void)
+{
+    guessed_disk_nature = true;
+    blk_cfg.blk_size = 2048;
+    blk_cfg.physical_block_exp = 0;
+}
+
 void virtio_assume_eckd(void)
 {
     guessed_disk_nature = true;

pc-bios/s390-ccw/virtio.h

@@ -187,6 +187,7 @@ typedef struct VirtioBlkConfig {
 bool virtio_guessed_disk_nature(void);
 void virtio_assume_scsi(void);
 void virtio_assume_eckd(void);
+void virtio_assume_iso9660(void);
 
 extern bool virtio_disk_is_scsi(void);
 extern bool virtio_disk_is_eckd(void);