Re: [PATCH 04/26] ppc/pnv: Use a simple incrementing index for the chip-id

[Greg Kurz <groug@kaod.org>]

On Mon, 9 Aug 2021 15:45:25 +0200
Cédric Le Goater <clg@kaod.org> wrote:

> When the QEMU PowerNV machine was introduced, multi chip support
> modeled a two socket system with dual chip modules as found on some P8
> Tuleta systems (8286-42A). But this is hardly used and not relevant
> for QEMU. Use a simple index instead.
> 

Makes sense.

> With this change, we can now increase the max socket number to 16 as
> found on high end systems.
> 
> Signed-off-by: Cédric Le Goater <clg@kaod.org>
> ---
>  include/hw/ppc/pnv.h | 33 +++++++--------------------------
>  hw/ppc/pnv.c         | 11 ++++++-----
>  2 files changed, 13 insertions(+), 31 deletions(-)
> 
> diff --git a/include/hw/ppc/pnv.h b/include/hw/ppc/pnv.h
> index 3fec7c87d82d..aa08d79d24de 100644
> --- a/include/hw/ppc/pnv.h
> +++ b/include/hw/ppc/pnv.h
> @@ -174,25 +174,6 @@ DECLARE_INSTANCE_CHECKER(PnvChip, PNV_CHIP_POWER9,
>  DECLARE_INSTANCE_CHECKER(PnvChip, PNV_CHIP_POWER10,
>                           TYPE_PNV_CHIP_POWER10)
>  
> -/*
> - * This generates a HW chip id depending on an index, as found on a
> - * two socket system with dual chip modules :
> - *
> - *    0x0, 0x1, 0x10, 0x11
> - *
> - * 4 chips should be the maximum
> - *
> - * TODO: use a machine property to define the chip ids
> - */
> -#define PNV_CHIP_HWID(i) ((((i) & 0x3e) << 3) | ((i) & 0x1))
> -
> -/*
> - * Converts back a HW chip id to an index. This is useful to calculate
> - * the MMIO addresses of some controllers which depend on the chip id.
> - */
> -#define PNV_CHIP_INDEX(chip)                                    \
> -    (((chip)->chip_id >> 2) * 2 + ((chip)->chip_id & 0x3))
> -
>  PowerPCCPU *pnv_chip_find_cpu(PnvChip *chip, uint32_t pir);
>  
>  #define TYPE_PNV_MACHINE       MACHINE_TYPE_NAME("powernv")
> @@ -256,11 +237,11 @@ void pnv_bmc_set_pnor(IPMIBmc *bmc, PnvPnor *pnor);
>  #define PNV_OCC_COMMON_AREA_SIZE    0x0000000000800000ull
>  #define PNV_OCC_COMMON_AREA_BASE    0x7fff800000ull
>  #define PNV_OCC_SENSOR_BASE(chip)   (PNV_OCC_COMMON_AREA_BASE + \
> -    PNV_OCC_SENSOR_DATA_BLOCK_BASE(PNV_CHIP_INDEX(chip)))
> +    PNV_OCC_SENSOR_DATA_BLOCK_BASE((chip)->chip_id))
>  
>  #define PNV_HOMER_SIZE              0x0000000000400000ull
>  #define PNV_HOMER_BASE(chip)                                            \
> -    (0x7ffd800000ull + ((uint64_t)PNV_CHIP_INDEX(chip)) * PNV_HOMER_SIZE)
> +    (0x7ffd800000ull + ((uint64_t)(chip)->chip_id) * PNV_HOMER_SIZE)
>  
>  
>  /*
> @@ -279,16 +260,16 @@ void pnv_bmc_set_pnor(IPMIBmc *bmc, PnvPnor *pnor);
>   */
>  #define PNV_ICP_SIZE         0x0000000000100000ull
>  #define PNV_ICP_BASE(chip)                                              \
> -    (0x0003ffff80000000ull + (uint64_t) PNV_CHIP_INDEX(chip) * PNV_ICP_SIZE)
> +    (0x0003ffff80000000ull + (uint64_t) (chip)->chip_id * PNV_ICP_SIZE)
>  
>  
>  #define PNV_PSIHB_SIZE       0x0000000000100000ull
>  #define PNV_PSIHB_BASE(chip) \
> -    (0x0003fffe80000000ull + (uint64_t)PNV_CHIP_INDEX(chip) * PNV_PSIHB_SIZE)
> +    (0x0003fffe80000000ull + (uint64_t)(chip)->chip_id * PNV_PSIHB_SIZE)
>  
>  #define PNV_PSIHB_FSP_SIZE   0x0000000100000000ull
>  #define PNV_PSIHB_FSP_BASE(chip) \
> -    (0x0003ffe000000000ull + (uint64_t)PNV_CHIP_INDEX(chip) * \
> +    (0x0003ffe000000000ull + (uint64_t)(chip)->chip_id * \
>       PNV_PSIHB_FSP_SIZE)
>  
>  /*
> @@ -324,11 +305,11 @@ void pnv_bmc_set_pnor(IPMIBmc *bmc, PnvPnor *pnor);
>  #define PNV9_OCC_COMMON_AREA_SIZE    0x0000000000800000ull
>  #define PNV9_OCC_COMMON_AREA_BASE    0x203fff800000ull
>  #define PNV9_OCC_SENSOR_BASE(chip)   (PNV9_OCC_COMMON_AREA_BASE +       \
> -    PNV_OCC_SENSOR_DATA_BLOCK_BASE(PNV_CHIP_INDEX(chip)))
> +    PNV_OCC_SENSOR_DATA_BLOCK_BASE((chip)->chip_id))
>  
>  #define PNV9_HOMER_SIZE              0x0000000000400000ull
>  #define PNV9_HOMER_BASE(chip)                                           \
> -    (0x203ffd800000ull + ((uint64_t)PNV_CHIP_INDEX(chip)) * PNV9_HOMER_SIZE)
> +    (0x203ffd800000ull + ((uint64_t)(chip)->chip_id) * PNV9_HOMER_SIZE)
>  
>  /*
>   * POWER10 MMIO base addresses - 16TB stride per chip
> diff --git a/hw/ppc/pnv.c b/hw/ppc/pnv.c
> index b122251d1a5d..025f01c55744 100644
> --- a/hw/ppc/pnv.c
> +++ b/hw/ppc/pnv.c
> @@ -809,9 +809,10 @@ static void pnv_init(MachineState *machine)
>       * TODO: should we decide on how many chips we can create based
>       * on #cores and Venice vs. Murano vs. Naples chip type etc...,
>       */
> -    if (!is_power_of_2(pnv->num_chips) || pnv->num_chips > 4) {
> +    if (!is_power_of_2(pnv->num_chips) || pnv->num_chips > 16) {
>          error_report("invalid number of chips: '%d'", pnv->num_chips);
> -        error_printf("Try '-smp sockets=N'. Valid values are : 1, 2 or 4.\n");
> +        error_printf(
> +            "Try '-smp sockets=N'. Valid values are : 1, 2, 4, 8 and 16.\n");
>          exit(1);
>      }
>  
> @@ -819,6 +820,7 @@ static void pnv_init(MachineState *machine)
>      for (i = 0; i < pnv->num_chips; i++) {
>          char chip_name[32];
>          Object *chip = OBJECT(qdev_new(chip_typename));
> +        int chip_id = i;
>  
>          pnv->chips[i] = PNV_CHIP(chip);
>  
> @@ -831,10 +833,9 @@ static void pnv_init(MachineState *machine)
>                                      &error_fatal);
>          }
>  
> -        snprintf(chip_name, sizeof(chip_name), "chip[%d]", PNV_CHIP_HWID(i));
> +        snprintf(chip_name, sizeof(chip_name), "chip[%d]", chip_id);

I'd rather pass directly the i variable. It is clear enough this is
the index of the chip in pnv->chips[]. No need for an intermediate
variable IMHO.

Anyway,

Reviewed-by: Greg Kurz <groug@kaod.org>

>          object_property_add_child(OBJECT(pnv), chip_name, chip);
> -        object_property_set_int(chip, "chip-id", PNV_CHIP_HWID(i),
> -                                &error_fatal);
> +        object_property_set_int(chip, "chip-id", chip_id, &error_fatal);
>          object_property_set_int(chip, "nr-cores", machine->smp.cores,
>                                  &error_fatal);
>          object_property_set_int(chip, "nr-threads", machine->smp.threads,