On Wed, 30 May 2018 11:16:58 +0200 Thomas Huth <th...@redhat.com> wrote:
> With the STSI instruction, we can get the UUID of the current VM instance, > so we can support loading pxelinux config files via UUID in the file name, > too. > > Signed-off-by: Thomas Huth <th...@redhat.com> > --- > pc-bios/s390-ccw/netmain.c | 46 > +++++++++++++++++++++++++++++++++++++++++++++- > 1 file changed, 45 insertions(+), 1 deletion(-) > > diff --git a/pc-bios/s390-ccw/netmain.c b/pc-bios/s390-ccw/netmain.c > index e84bb2b..7ece302 100644 > --- a/pc-bios/s390-ccw/netmain.c > +++ b/pc-bios/s390-ccw/netmain.c > @@ -235,6 +235,49 @@ static void net_release(filename_ip_t *fn_ip) > } > > /** > + * Retrieve the Universally Unique Identifier of the VM. > + * @return UUID string, or NULL in case of errors > + */ > +static const char *get_uuid(void) > +{ > + register int r0 asm("0"); > + register int r1 asm("1"); > + uint8_t *mem, *buf, uuid[16]; > + int i, chk = 0; > + static char uuid_str[37]; > + > + mem = malloc(2 * PAGE_SIZE); > + if (!mem) { > + puts("Out of memory ... can not get UUID."); > + return NULL; > + } > + buf = (uint8_t *)(((uint64_t)mem + PAGE_SIZE - 1) & ~(PAGE_SIZE - 1)); > + memset(buf, 0, PAGE_SIZE); > + > + /* Get SYSIB 3.2.2 */ > + r0 = (3 << 28) | 2; > + r1 = 2; > + asm volatile(" stsi 0(%2)\n" : : "d" (r0), "d" (r1), "a" (buf) > + : "cc", "memory"); Maybe check for cc == 3 here, just to be safe? (We can probably assume a dbct >= 1 if it is successful, I think.) > + > + for (i = 0; i < 16; i++) { > + uuid[i] = buf[8 * 4 + 12 * 4 + i]; Is there some way to make this offset less magic (offset of first vmdb + offset of uuid inside vmdb)? > + chk |= uuid[i]; > + } > + free(mem); > + if (!chk) { > + return NULL; > + } > + > + sprintf(uuid_str, "%02x%02x%02x%02x-%02x%02x-%02x%02x-%02x%02x-" > + "%02x%02x%02x%02x%02x%02x", uuid[0], uuid[1], uuid[2], uuid[3], > + uuid[4], uuid[5], uuid[6], uuid[7], uuid[8], uuid[9], uuid[10], > + uuid[11], uuid[12], uuid[13], uuid[14], uuid[15]); > + > + return uuid_str; > +} > + > +/** > * Load a kernel with initrd (i.e. with the information that we've got from > * a pxelinux.cfg config file) > */ > @@ -284,7 +327,8 @@ static int net_try_pxelinux_cfg(filename_ip_t *fn_ip) > struct pl_cfg_entry entries[MAX_PXELINUX_ENTRIES]; > int num_ent, def_ent = 0; > > - num_ent = pxelinux_load_parse_cfg(fn_ip, mac, NULL, DEFAULT_TFTP_RETRIES, > + num_ent = pxelinux_load_parse_cfg(fn_ip, mac, get_uuid(), > + DEFAULT_TFTP_RETRIES, > cfgbuf, sizeof(cfgbuf), > entries, MAX_PXELINUX_ENTRIES, > &def_ent); > if (num_ent > 0) {