Re: [PATCH 3/3] ipmi/bmc-sim: Add 'Get Channel Info' command

[Corey Minyard <corey@minyard.net>]

On Mon, Mar 31, 2025 at 10:57:24PM +1000, Nicholas Piggin wrote:
> Linux issues this command when booting a powernv machine.

This is good, just a couple of nits.

> 
> Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
> ---
>  include/hw/ipmi/ipmi.h | 14 +++++++++++
>  hw/ipmi/ipmi_bmc_sim.c | 56 ++++++++++++++++++++++++++++++++++++++++--
>  hw/ipmi/ipmi_bt.c      |  2 ++
>  hw/ipmi/ipmi_kcs.c     |  1 +
>  4 files changed, 71 insertions(+), 2 deletions(-)
> 
> diff --git a/include/hw/ipmi/ipmi.h b/include/hw/ipmi/ipmi.h
> index 77a7213ed93..5f01a50cd86 100644
> --- a/include/hw/ipmi/ipmi.h
> +++ b/include/hw/ipmi/ipmi.h
> @@ -41,6 +41,15 @@ enum ipmi_op {
>      IPMI_SEND_NMI
>  };
>  
> +/* Channel properties */
> +#define IPMI_CHANNEL_IPMB                0x00
> +#define IPMI_CHANNEL_SYSTEM              0x0f
> +#define IPMI_CH_MEDIUM_IPMB              0x01
> +#define IPMI_CH_MEDIUM_SYSTEM            0x0c
> +#define IPMI_CH_PROTOCOL_IPMB            0x01
> +#define IPMI_CH_PROTOCOL_KCS             0x05
> +#define IPMI_CH_PROTOCOL_BT_15           0x08

I know it's picky, but could you spell out CHANNEL here?

> +
>  #define IPMI_CC_INVALID_CMD                              0xc1
>  #define IPMI_CC_COMMAND_INVALID_FOR_LUN                  0xc2
>  #define IPMI_CC_TIMEOUT                                  0xc3
> @@ -170,6 +179,11 @@ struct IPMIInterfaceClass {
>       * Return the firmware info for a device.
>       */
>      void (*get_fwinfo)(struct IPMIInterface *s, IPMIFwInfo *info);
> +
> +    /*
> +     * IPMI channel protocol type number.
> +     */
> +    uint8_t protocol;
>  };
>  
>  /*
> diff --git a/hw/ipmi/ipmi_bmc_sim.c b/hw/ipmi/ipmi_bmc_sim.c
> index 8c3313aa65f..9198f854bd9 100644
> --- a/hw/ipmi/ipmi_bmc_sim.c
> +++ b/hw/ipmi/ipmi_bmc_sim.c
> @@ -70,6 +70,7 @@
>  #define IPMI_CMD_GET_MSG                  0x33
>  #define IPMI_CMD_SEND_MSG                 0x34
>  #define IPMI_CMD_READ_EVT_MSG_BUF         0x35
> +#define IPMI_CMD_GET_CHANNEL_INFO         0x42
>  
>  #define IPMI_NETFN_STORAGE            0x0a
>  
> @@ -1033,8 +1034,8 @@ static void send_msg(IPMIBmcSim *ibs,
>      uint8_t *buf;
>      uint8_t netfn, rqLun, rsLun, rqSeq;
>  
> -    if (cmd[2] != 0) {
> -        /* We only handle channel 0 with no options */
> +    if (cmd[2] != IPMI_CHANNEL_IPMB) {
> +        /* We only handle channel 0h (IPMB) with no options */
>          rsp_buffer_set_error(rsp, IPMI_CC_INVALID_DATA_FIELD);
>          return;
>      }
> @@ -1232,6 +1233,56 @@ static void get_watchdog_timer(IPMIBmcSim *ibs,
>      }
>  }
>  
> +static void get_channel_info(IPMIBmcSim *ibs,
> +                             uint8_t *cmd, unsigned int cmd_len,
> +                             RspBuffer *rsp)
> +{
> +    IPMIInterface *s = ibs->parent.intf;
> +    IPMIInterfaceClass *k = IPMI_INTERFACE_GET_CLASS(s);
> +    uint8_t ch = cmd[1] & 0x0f;
> +
> +    /* Only define channel 0h (IPMB) and Fh (system interface) */
> +
> +    if (ch == 0x0e) { /* "This channel" */
> +        ch = IPMI_CHANNEL_SYSTEM;
> +    }
> +    rsp_buffer_push(rsp, ch);
> +
> +    if (ch != IPMI_CHANNEL_IPMB && ch != IPMI_CHANNEL_SYSTEM) {
> +        /* Not supported */

I think that an all zero response is a valid response.  I think you
should return a IPMI_CC_INVALID_DATA_FIELD instead, right?

> +        int i;
> +        for (i = 0; i < 8; i++) {
> +            rsp_buffer_push(rsp, 0x00);
> +        }
> +        return;
> +    }
> +
> +    if (ch == IPMI_CHANNEL_IPMB) {
> +        rsp_buffer_push(rsp, IPMI_CH_MEDIUM_IPMB);
> +        rsp_buffer_push(rsp, IPMI_CH_PROTOCOL_IPMB);
> +    } else { /* IPMI_CHANNEL_SYSTEM */
> +        rsp_buffer_push(rsp, IPMI_CH_MEDIUM_SYSTEM);
> +        rsp_buffer_push(rsp, k->protocol);
> +    }
> +
> +    rsp_buffer_push(rsp, 0x00); /* Session-less */
> +
> +    /* IPMI Vendor ID */
> +    rsp_buffer_push(rsp, 0xf2);
> +    rsp_buffer_push(rsp, 0x1b);
> +    rsp_buffer_push(rsp, 0x00);

Where does this come from?

> +
> +    if (ch == IPMI_CHANNEL_SYSTEM) {
> +        /* IRQ assigned by ACPI/PnP (XXX?) */
> +        rsp_buffer_push(rsp, 0x60);
> +        rsp_buffer_push(rsp, 0x60);

The interrupt should be available.  For the isa versions there is a
get_fwinfo function pointer that you can fetch this with.  For PCI it's
more complicated, unfortunately.

-corey

> +    } else {
> +        /* Reserved */
> +        rsp_buffer_push(rsp, 0x00);
> +        rsp_buffer_push(rsp, 0x00);
> +    }
> +}
> +
>  static void get_sdr_rep_info(IPMIBmcSim *ibs,
>                               uint8_t *cmd, unsigned int cmd_len,
>                               RspBuffer *rsp)
> @@ -2028,6 +2079,7 @@ static const IPMICmdHandler app_cmds[] = {
>      [IPMI_CMD_RESET_WATCHDOG_TIMER] = { reset_watchdog_timer },
>      [IPMI_CMD_SET_WATCHDOG_TIMER] = { set_watchdog_timer, 8 },
>      [IPMI_CMD_GET_WATCHDOG_TIMER] = { get_watchdog_timer },
> +    [IPMI_CMD_GET_CHANNEL_INFO] = { get_channel_info, 3 },
>  };
>  static const IPMINetfn app_netfn = {
>      .cmd_nums = ARRAY_SIZE(app_cmds),
> diff --git a/hw/ipmi/ipmi_bt.c b/hw/ipmi/ipmi_bt.c
> index 583fc64730c..d639c151c4d 100644
> --- a/hw/ipmi/ipmi_bt.c
> +++ b/hw/ipmi/ipmi_bt.c
> @@ -434,4 +434,6 @@ void ipmi_bt_class_init(IPMIInterfaceClass *iic)
>      iic->handle_if_event = ipmi_bt_handle_event;
>      iic->set_irq_enable = ipmi_bt_set_irq_enable;
>      iic->reset = ipmi_bt_handle_reset;
> +    /* BT System Interface Format, IPMI v1.5 */
> +    iic->protocol = IPMI_CH_PROTOCOL_BT_15;
>  }
> diff --git a/hw/ipmi/ipmi_kcs.c b/hw/ipmi/ipmi_kcs.c
> index c15977cab4c..8af7698286d 100644
> --- a/hw/ipmi/ipmi_kcs.c
> +++ b/hw/ipmi/ipmi_kcs.c
> @@ -420,4 +420,5 @@ void ipmi_kcs_class_init(IPMIInterfaceClass *iic)
>      iic->handle_rsp = ipmi_kcs_handle_rsp;
>      iic->handle_if_event = ipmi_kcs_handle_event;
>      iic->set_irq_enable = ipmi_kcs_set_irq_enable;
> +    iic->protocol = IPMI_CH_PROTOCOL_KCS;
>  }
> -- 
> 2.47.1
>