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 <thuth@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");
+
+    for (i = 0; i < 16; i++) {
+        uuid[i] = buf[8 * 4 + 12 * 4 + i];
+        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) {
-- 
1.8.3.1

Reviewed-by: Farhan Ali <alifm@linux.ibm.com>

On Wed, 30 May 2018 11:16:58 +0200
Thomas Huth <thuth@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 <thuth@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) {

On 04.06.2018 11:36, Cornelia Huck wrote:
> On Wed, 30 May 2018 11:16:58 +0200
> Thomas Huth <thuth@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 <thuth@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.)

Sure, I can add that check. In case it's not available, this should have
been catched by the "if (!chk)" below, but let's better be safe than
sorry here.

>> +
>> +    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)?

Would a comment be sufficient? Or shall I copy the SysIB_322 structure
from target/s390x/cpu.h over to the s390-ccw bios?

 Thomas

On Tue, 5 Jun 2018 14:04:18 +0200
Thomas Huth <thuth@redhat.com> wrote:

> On 04.06.2018 11:36, Cornelia Huck wrote:
> > On Wed, 30 May 2018 11:16:58 +0200
> > Thomas Huth <thuth@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 <thuth@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.)  
> 
> Sure, I can add that check. In case it's not available, this should have
> been catched by the "if (!chk)" below, but let's better be safe than
> sorry here.
> 
> >> +
> >> +    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)?  
> 
> Would a comment be sufficient? Or shall I copy the SysIB_322 structure
> from target/s390x/cpu.h over to the s390-ccw bios?

Copying the whole structure looks like overkill. What about

/* offset of first vmdb + offset of uuid inside vmdb */
#define VMDB_UUID_OFFSET (8 * 4 + 12 *4)

and using buf[VMDB_UUID_OFFSET + i]?

(If I see static expressions with concrete numbers, my eyes tend to
glaze over :)