Re: [Qemu-devel] [PATCH v2] ipmi: add SET_SENSOR_READING command

["Michael S. Tsirkin" <mst@redhat.com>]

On Wed, Apr 12, 2017 at 09:08:50AM +0200, Cédric Le Goater wrote:
> SET_SENSOR_READING is a complex IPMI command (see IPMI spec 35.17)
> which enables the host software to set the reading value and the event
> status of sensors supporting it.
> 
> Below is a proposal for all the operations (reading, assert, deassert,
> event data) with the following limitations :
> 
>  - No event are generated for threshold-based sensors. 
>  - The case in which the BMC needs to generate its own events is not
>    supported.
>    
> Signed-off-by: Cédric Le Goater <clg@kaod.org>

Need to look at how guests will behave if they start on
a new QEMU and migrate to old one.
Any input? Do we need a flag to behave like 2.9 did if
we want compatibility?

> ---
> 
>  Corey,
> 
>  There is some progress but I didn't add a check on the value before
>  generating events because we would not generate an event when only
>  the event bytes change. 
> 
>  Changes since v1:
>  
>  - created copies of the reading and the assertion bits before
>    committing the values
>  - added some TODOs
>  - handled inconsistent Event Data Bytes operation
>  
>  hw/ipmi/ipmi_bmc_sim.c |  213 +++++++++++++++++++++++++++++++++++++++++++++++++
>  1 file changed, 213 insertions(+)
> 
> Index: qemu-powernv-2.9.git/hw/ipmi/ipmi_bmc_sim.c
> ===================================================================
> --- qemu-powernv-2.9.git.orig/hw/ipmi/ipmi_bmc_sim.c
> +++ qemu-powernv-2.9.git/hw/ipmi/ipmi_bmc_sim.c
> @@ -45,6 +45,7 @@
>  #define IPMI_CMD_GET_SENSOR_READING       0x2d
>  #define IPMI_CMD_SET_SENSOR_TYPE          0x2e
>  #define IPMI_CMD_GET_SENSOR_TYPE          0x2f
> +#define IPMI_CMD_SET_SENSOR_READING       0x30
>  
>  /* #define IPMI_NETFN_APP             0x06 In ipmi.h */
>  
> @@ -1739,6 +1740,217 @@ static void get_sensor_type(IPMIBmcSim *
>      rsp_buffer_push(rsp, sens->evt_reading_type_code);
>  }
>  
> +/*
> + * bytes   parameter
> + *    1    sensor number
> + *    2    operation (see below for bits meaning)
> + *    3    sensor reading
> + *  4:5    assertion states (optional)
> + *  6:7    deassertion states (optional)
> + *  8:10   event data 1,2,3 (optional)
> + */
> +static void set_sensor_reading(IPMIBmcSim *ibs,
> +                               uint8_t *cmd, unsigned int cmd_len,
> +                               RspBuffer *rsp)
> +{
> +    IPMISensor *sens;
> +    uint8_t evd1 = 0;
> +    uint8_t evd2 = 0;
> +    uint8_t evd3 = 0;
> +    uint8_t new_reading = 0;
> +    uint16_t new_assert_states = 0;
> +    uint16_t new_deassert_states = 0;
> +    bool change_reading = false;
> +    bool change_assert = false;
> +    bool change_deassert = false;
> +    enum {
> +        SENSOR_GEN_EVENT_NONE,
> +        SENSOR_GEN_EVENT_DATA,
> +        SENSOR_GEN_EVENT_BMC,
> +    } do_gen_event = SENSOR_GEN_EVENT_NONE;
> +
> +    if ((cmd[2] >= MAX_SENSORS) ||
> +            !IPMI_SENSOR_GET_PRESENT(ibs->sensors + cmd[2])) {
> +        rsp_buffer_set_error(rsp, IPMI_CC_REQ_ENTRY_NOT_PRESENT);
> +        return;
> +    }
> +
> +    sens = ibs->sensors + cmd[2];
> +
> +    /* [1:0] Sensor Reading operation */
> +    switch ((cmd[3]) & 0x3) {
> +    case 0: /* Do not change */
> +        break;
> +    case 1: /* write given value to sensor reading byte */
> +        new_reading = cmd[4];
> +        if (sens->reading != new_reading) {
> +            change_reading = true;
> +        }
> +        break;
> +    case 2:
> +    case 3:
> +        rsp_buffer_set_error(rsp, IPMI_CC_INVALID_DATA_FIELD);
> +        return;
> +    }
> +
> +    /* [3:2] Deassertion bits operation */
> +    switch ((cmd[3] >> 2) & 0x3) {
> +    case 0: /* Do not change */
> +        break;
> +    case 1: /* write given value */
> +        if (cmd_len > 7) {
> +            new_deassert_states = cmd[7];
> +            change_deassert = true;
> +        }
> +        if (cmd_len > 8) {
> +            new_deassert_states |= (cmd[8] << 8);
> +        }
> +        break;
> +
> +    case 2: /* mask on */
> +        if (cmd_len > 7) {
> +            new_deassert_states = (sens->deassert_states | cmd[7]);
> +            change_deassert = true;
> +        }
> +        if (cmd_len > 8) {
> +            new_deassert_states |= (sens->deassert_states | (cmd[8] << 8));
> +        }
> +        break;
> +
> +    case 3: /* mask off */
> +        if (cmd_len > 7) {
> +            new_deassert_states = (sens->deassert_states & cmd[7]);
> +            change_deassert = true;
> +        }
> +        if (cmd_len > 8) {
> +            new_deassert_states |= (sens->deassert_states & (cmd[8] << 8));
> +        }
> +        break;
> +    }
> +
> +    if (change_deassert && (new_deassert_states == sens->deassert_states)) {
> +        change_deassert = false;
> +    }
> +
> +    /* [5:4] Assertion bits operation */
> +    switch ((cmd[3] >> 4) & 0x3) {
> +    case 0: /* Do not change */
> +        break;
> +    case 1: /* write given value */
> +        if (cmd_len > 5) {
> +            new_assert_states = cmd[5];
> +            change_assert = true;
> +        }
> +        if (cmd_len > 6) {
> +            new_assert_states |= (cmd[6] << 8);
> +        }
> +        break;
> +
> +    case 2: /* mask on */
> +        if (cmd_len > 5) {
> +            new_assert_states = (sens->assert_states | cmd[5]);
> +            change_assert = true;
> +        }
> +        if (cmd_len > 6) {
> +            new_assert_states |= (sens->assert_states | (cmd[6] << 8));
> +        }
> +        break;
> +
> +    case 3: /* mask off */
> +        if (cmd_len > 5) {
> +            new_assert_states = (sens->assert_states & cmd[5]);
> +            change_assert = true;
> +        }
> +        if (cmd_len > 6) {
> +            new_assert_states |= (sens->assert_states & (cmd[6] << 8));
> +        }
> +        break;
> +    }
> +
> +    if (change_assert && (new_assert_states == sens->assert_states)) {
> +        change_assert = false;
> +    }
> +
> +    if (cmd_len > 9) {
> +        evd1 = cmd[9];
> +    }
> +    if (cmd_len > 10) {
> +        evd2 = cmd[10];
> +    }
> +    if (cmd_len > 11) {
> +        evd3 = cmd[11];
> +    }
> +
> +    /* [7:6] Event Data Bytes operation */
> +    switch ((cmd[3] >> 6) & 0x3) {
> +    case 0: /* Don’t use Event Data bytes from this command. BMC will
> +             * generate it's own Event Data bytes based on its sensor
> +             * implementation.  */
> +        evd1 = evd2 = evd3 = 0x0;
> +        do_gen_event = SENSOR_GEN_EVENT_BMC;
> +        break;
> +    case 1: /* Write given values to event data bytes including bits
> +             * [3:0] Event Data 1. */
> +        do_gen_event = SENSOR_GEN_EVENT_DATA;
> +        break;
> +    case 2: /* Write given values to event data bytes excluding bits
> +             * [3:0] Event Data 1. */
> +        evd1 &= 0xf0;
> +        do_gen_event = SENSOR_GEN_EVENT_DATA;
> +        break;
> +    case 3:
> +        rsp_buffer_set_error(rsp, IPMI_CC_INVALID_DATA_FIELD);
> +        return;
> +    }
> +
> +    /* Event Data Bytes operation and parameter are inconsistent. The
> +     * Specs are not clear on that topic but generating an error seems
> +     * correct. */
> +    if (do_gen_event == SENSOR_GEN_EVENT_DATA && cmd_len < 10) {
> +        rsp_buffer_set_error(rsp, IPMI_CC_INVALID_DATA_FIELD);
> +        return;
> +    }
> +
> +    /* commit values */
> +    if (change_reading) {
> +        sens->reading = new_reading;
> +    }
> +
> +    if (change_assert) {
> +        sens->assert_states = new_assert_states;
> +    }
> +
> +    if (change_deassert) {
> +        sens->deassert_states = new_deassert_states;
> +    }
> +
> +    /* TODO: handle threshold sensor */
> +    if (!IPMI_SENSOR_IS_DISCRETE(sens)) {
> +        return;
> +    }
> +
> +    switch (do_gen_event) {
> +    case SENSOR_GEN_EVENT_DATA: {
> +        unsigned int bit = evd1 & 0xf;
> +        uint16_t mask = (1 << bit);
> +
> +        if (sens->assert_states & mask & sens->assert_enable) {
> +            gen_event(ibs, cmd[2], 0, evd1, evd2, evd3);
> +        }
> +
> +        if (sens->deassert_states & mask & sens->deassert_enable) {
> +            gen_event(ibs, cmd[2], 1, evd1, evd2, evd3);
> +        }
> +    }
> +        break;
> +    case SENSOR_GEN_EVENT_BMC:
> +        /* TODO: generate event and event data bytes depending on the
> +         * sensor */
> +        break;
> +    case SENSOR_GEN_EVENT_NONE:
> +        break;
> +    }
> +}
>  
>  static const IPMICmdHandler chassis_cmds[] = {
>      [IPMI_CMD_GET_CHASSIS_CAPABILITIES] = { chassis_capabilities },
> @@ -1759,6 +1971,7 @@ static const IPMICmdHandler sensor_event
>      [IPMI_CMD_GET_SENSOR_READING] = { get_sensor_reading, 3 },
>      [IPMI_CMD_SET_SENSOR_TYPE] = { set_sensor_type, 5 },
>      [IPMI_CMD_GET_SENSOR_TYPE] = { get_sensor_type, 3 },
> +    [IPMI_CMD_SET_SENSOR_READING] = { set_sensor_reading, 5 },
>  };
>  static const IPMINetfn sensor_event_netfn = {
>      .cmd_nums = ARRAY_SIZE(sensor_event_cmds),