Re: [Qemu-devel] [PATCH v2 4/9] ipmi: introduce a struct ipmi_sdr_compact

["Cédric Le Goater" <clg@fr.ibm.com>]

On 01/22/2016 11:49 AM, Greg Kurz wrote:
> On Thu, 21 Jan 2016 18:18:49 +0100
> Cédric Le Goater <clg@fr.ibm.com> wrote:
> 
>> Currently, sdr attributes are identified using byte offsets and this
>> can be a bit confusing.
>>
>> This patch adds a struct ipmi_sdr_compact conforming to the IPMI specs
>> and replaces byte offsets with names. It also introduces and uses a
>> struct ipmi_sdr_header in sections of the code where no assumption is
>> made on the type of SDR. This leave rooms to potential usage of other
>> types in the future.
>>
> 
> Turning all these magic numbers into understandable names is definitely a
> great idea !
> 
> See comments below.
> 
>> Signed-off-by: Cédric Le Goater <clg@fr.ibm.com>
>> ---
>>  hw/ipmi/ipmi_bmc_sim.c | 65 +++++++++++++++++++++++++++++++-------------------
>>  include/hw/ipmi/ipmi.h | 44 ++++++++++++++++++++++++++++++++++
>>  2 files changed, 84 insertions(+), 25 deletions(-)
>>
>> diff --git a/hw/ipmi/ipmi_bmc_sim.c b/hw/ipmi/ipmi_bmc_sim.c
>> index fc596a548df7..31f990199154 100644
>> --- a/hw/ipmi/ipmi_bmc_sim.c
>> +++ b/hw/ipmi/ipmi_bmc_sim.c
>> @@ -323,11 +323,15 @@ static void sdr_inc_reservation(IPMISdr *sdr)
>>  static int sdr_add_entry(IPMIBmcSim *ibs, const uint8_t *entry,
>>                           unsigned int len, uint16_t *recid)
>>  {
>> +    struct ipmi_sdr_header *sdrh_entry = (struct ipmi_sdr_header *) entry;
> 
> This looks like the entry argument should be struct ipmi_sdr_header * and
> you would not need sdrh_entry.

Indeed and it improves readability a little more. I will send a fix in next
patchset. 

>> +    struct ipmi_sdr_header *sdrh =
>> +        (struct ipmi_sdr_header *) &ibs->sdr.sdr[ibs->sdr.next_free];
>> +
>>      if ((len < 5) || (len > 255)) {
>>          return 1;
>>      }
>>
>> -    if (entry[4] != len - 5) {
>> +    if (sdrh_entry->rec_length != len - 5) {
>>          return 1;
>>      }
>>
>> @@ -336,10 +340,10 @@ static int sdr_add_entry(IPMIBmcSim *ibs, const uint8_t *entry,
>>          return 1;
>>      }
>>
>> -    memcpy(ibs->sdr.sdr + ibs->sdr.next_free, entry, len);
>> -    ibs->sdr.sdr[ibs->sdr.next_free] = ibs->sdr.next_rec_id & 0xff;
>> -    ibs->sdr.sdr[ibs->sdr.next_free+1] = (ibs->sdr.next_rec_id >> 8) & 0xff;
>> -    ibs->sdr.sdr[ibs->sdr.next_free+2] = 0x51; /* Conform to IPMI 1.5 spec */
>> +    memcpy(sdrh, entry, len);
>> +    sdrh->rec_id[0] = ibs->sdr.next_rec_id & 0xff;
>> +    sdrh->rec_id[1] = (ibs->sdr.next_rec_id >> 8) & 0xff;
>> +    sdrh->sdr_version = 0x51; /* Conform to IPMI 1.5 spec */
>>
>>      if (recid) {
>>          *recid = ibs->sdr.next_rec_id;
>> @@ -357,8 +361,10 @@ static int sdr_find_entry(IPMISdr *sdr, uint16_t recid,
>>      unsigned int pos = *retpos;
>>
>>      while (pos < sdr->next_free) {
>> -        uint16_t trec = sdr->sdr[pos] | (sdr->sdr[pos + 1] << 8);
>> -        unsigned int nextpos = pos + sdr->sdr[pos + 4];
>> +        struct ipmi_sdr_header *sdrh =
>> +            (struct ipmi_sdr_header *) &sdr->sdr[pos];
>> +        uint16_t trec = ipmi_sdr_recid(sdrh);
>> +        unsigned int nextpos = pos + sdrh->rec_length;
>>
>>          if (trec == recid) {
>>              if (nextrec) {
>> @@ -507,29 +513,32 @@ static void ipmi_init_sensors_from_sdrs(IPMIBmcSim *s)
>>
>>      pos = 0;
>>      for (i = 0; !sdr_find_entry(&s->sdr, i, &pos, NULL); i++) {
>> -        uint8_t *sdr = s->sdr.sdr + pos;
>> -        unsigned int len = sdr[4];
>> +        struct ipmi_sdr_compact *sdr =
>> +            (struct ipmi_sdr_compact *) &s->sdr.sdr[pos];
>> +        unsigned int len = sdr->header.rec_length;
>>
>>          if (len < 20) {
>>              continue;
>>          }
>> -        if ((sdr[3] < 1) || (sdr[3] > 2)) {
>> +        if (sdr->header.rec_type != IPMI_SDR_COMPACT_TYPE) {
>>              continue; /* Not a sensor SDR we set from */
>>          }
>>
>> -        if (sdr[7] > MAX_SENSORS) {
>> +        if (sdr->sensor_owner_number > MAX_SENSORS) {
>>              continue;
>>          }
>> -        sens = s->sensors + sdr[7];
>> +        sens = s->sensors + sdr->sensor_owner_number;
>>
>>          IPMI_SENSOR_SET_PRESENT(sens, 1);
>> -        IPMI_SENSOR_SET_SCAN_ON(sens, (sdr[10] >> 6) & 1);
>> -        IPMI_SENSOR_SET_EVENTS_ON(sens, (sdr[10] >> 5) & 1);
>> -        sens->assert_suppt = sdr[14] | (sdr[15] << 8);
>> -        sens->deassert_suppt = sdr[16] | (sdr[17] << 8);
>> -        sens->states_suppt = sdr[18] | (sdr[19] << 8);
>> -        sens->sensor_type = sdr[12];
>> -        sens->evt_reading_type_code = sdr[13] & 0x7f;
>> +        IPMI_SENSOR_SET_SCAN_ON(sens, (sdr->sensor_init >> 6) & 1);
>> +        IPMI_SENSOR_SET_EVENTS_ON(sens, (sdr->sensor_init >> 5) & 1);
>> +        sens->assert_suppt = sdr->assert_mask[0] | (sdr->assert_mask[1] << 8);
>> +        sens->deassert_suppt =
>> +            sdr->deassert_mask[0] | (sdr->deassert_mask[1] << 8);
>> +        sens->states_suppt =
>> +            sdr->discrete_mask[0] | (sdr->discrete_mask[1] << 8);
>> +        sens->sensor_type = sdr->sensor_type;
>> +        sens->evt_reading_type_code = sdr->reading_type & 0x7f;
>>
>>          /* Enable all the events that are supported. */
>>          sens->assert_enable = sens->assert_suppt;
>> @@ -1155,6 +1164,7 @@ static void get_sdr(IPMIBmcSim *ibs,
>>  {
>>      unsigned int pos;
>>      uint16_t nextrec;
>> +    struct ipmi_sdr_header *sdrh;
>>
>>      IPMI_CHECK_CMD_LEN(8);
>>      if (cmd[6]) {
>> @@ -1166,7 +1176,10 @@ static void get_sdr(IPMIBmcSim *ibs,
>>          rsp[2] = IPMI_CC_REQ_ENTRY_NOT_PRESENT;
>>          return;
>>      }
>> -    if (cmd[6] > (ibs->sdr.sdr[pos + 4])) {
>> +
>> +    sdrh = (struct ipmi_sdr_header *) &ibs->sdr.sdr[pos];
>> +
>> +    if (cmd[6] > sdrh->rec_length) {
>>          rsp[2] = IPMI_CC_PARM_OUT_OF_RANGE;
>>          return;
>>      }
>> @@ -1175,7 +1188,7 @@ static void get_sdr(IPMIBmcSim *ibs,
>>      IPMI_ADD_RSP_DATA((nextrec >> 8) & 0xff);
>>
>>      if (cmd[7] == 0xff) {
>> -        cmd[7] = ibs->sdr.sdr[pos + 4] - cmd[6];
>> +        cmd[7] = sdrh->rec_length - cmd[6];
>>      }
>>
>>      if ((cmd[7] + *rsp_len) > max_rsp_len) {
>> @@ -1644,18 +1657,20 @@ static void ipmi_sim_init(Object *obj)
>>      }
>>
>>      for (i = 0;;) {
>> +        struct ipmi_sdr_header *sdrh;
>>          int len;
>>          if ((i + 5) > sizeof(init_sdrs)) {
>> -            error_report("Problem with recid 0x%4.4x: \n", i);
>> +            error_report("Problem with recid 0x%4.4x", i);
> 
> Unrelated change.

OK. I will pull these changes in a preliminary patch.

>>              return;
>>          }
>> -        len = init_sdrs[i + 4];
>> -        recid = init_sdrs[i] | (init_sdrs[i + 1] << 8);
>> +        sdrh = (struct ipmi_sdr_header *) &init_sdrs[i];
> 
> Maybe init_sdrs could be turned into something which already has explicit
> struct ipmi_sdr_header fields ?

I don't necessarily agree here but may be, the name is confusing 
and should be something like 'sdr_blob', which will make more sense
when we load sdrs from a file. 

init_sdrs contains raw data and this routine loops over it to find 
enough bytes for a minimal ipmi sdr header, and then enough bytes 
to add a sdr entry in the BMC table. So we are manipulating bytes
all the time until the end when we :

	sdr_add_entry(ibs, init_sdrs + i, len, NULL);

Your suggestion on changing sdr_add_entry() API improves the code 
a little.

Thanks !

C.


> 
>> +        len = sdrh->rec_length;
>> +        recid = ipmi_sdr_recid(sdrh);
>>          if (recid == 0xffff) {
>>              break;
>>          }
>>          if ((i + len + 5) > sizeof(init_sdrs)) {
>> -            error_report("Problem with recid 0x%4.4x\n", i);
>> +            error_report("Problem with recid 0x%4.4x", i);
> 
> Unrelated change.
> 
>>              return;
>>          }
>>          sdr_add_entry(ibs, init_sdrs + i, len, NULL);
>> diff --git a/include/hw/ipmi/ipmi.h b/include/hw/ipmi/ipmi.h
>> index 32bac0fa8877..7e142e241dcb 100644
>> --- a/include/hw/ipmi/ipmi.h
>> +++ b/include/hw/ipmi/ipmi.h
>> @@ -210,4 +210,48 @@ IPMIFwInfo *ipmi_next_fwinfo(IPMIFwInfo *current);
>>  #define ipmi_debug(fs, ...)
>>  #endif
>>
>> +struct ipmi_sdr_header {
>> +    uint8_t  rec_id[2];
>> +    uint8_t  sdr_version;               /* 0x51 */
>> +    uint8_t  rec_type;
>> +    uint8_t  rec_length;
>> +};
>> +#define IPMI_SDR_HEADER_SIZE     sizeof(struct ipmi_sdr_header)
>> +
>> +#define ipmi_sdr_recid(sdr) ((sdr)->rec_id[0] | ((sdr)->rec_id[1] << 8))
>> +
>> +/*
>> + * 43.2 SDR Type 02h. Compact Sensor Record
>> + */
>> +#define IPMI_SDR_COMPACT_TYPE    2
>> +
>> +struct ipmi_sdr_compact {
>> +    struct ipmi_sdr_header header;
>> +
>> +    uint8_t  sensor_owner_id;
>> +    uint8_t  sensor_owner_lun;
>> +    uint8_t  sensor_owner_number;       /* byte 8 */
>> +    uint8_t  entity_id;
>> +    uint8_t  entity_instance;
>> +    uint8_t  sensor_init;
>> +    uint8_t  sensor_caps;
>> +    uint8_t  sensor_type;
>> +    uint8_t  reading_type;
>> +    uint8_t  assert_mask[2];            /* byte 16 */
>> +    uint8_t  deassert_mask[2];
>> +    uint8_t  discrete_mask[2];
>> +    uint8_t  sensor_unit1;
>> +    uint8_t  sensor_unit2;
>> +    uint8_t  sensor_unit3;
>> +    uint8_t  sensor_direction[2];       /* byte 24 */
>> +    uint8_t  positive_threshold;
>> +    uint8_t  negative_threshold;
>> +    uint8_t  reserved[3];
>> +    uint8_t  oem;
>> +    uint8_t  id_str_len;                /* byte 32 */
>> +    uint8_t  id_string[16];
>> +};
>> +
>> +typedef uint8_t ipmi_sdr_compact_buffer[sizeof(struct ipmi_sdr_compact)];
>> +
>>  #endif
>