Re: [PATCH v4 4/5] ppc/pnv: Introduce user creatable pnv-phb4 devices

["Cédric Le Goater" <clg@kaod.org>]

On 1/11/22 01:55, Daniel Henrique Barboza wrote:
> This patch introduces pnv-phb4 user creatable devices that are created
> in a similar manner as pnv-phb3 devices, allowing the user to interact
> with the PHBs directly instead of creating PCI Express Controllers that
> will create a certain amount of PHBs per controller index.
> 
> We accomplish this by doing the following:
> 
> - add a pnv_phb4_get_stack() helper to retrieve which stack an user
> created phb4 would occupy;
> 
> - when dealing with an user created pnv-phb4 (detected by checking if
> phb->stack is NULL at the start of phb4_realize()), retrieve its stack
> and initialize its properties as done in stk_realize();
> 
> - use 'defaults_enabled()' in stk_realize() to avoid creating and
> initializing a 'stack->phb' qdev that might be overwritten by an user
> created pnv-phb4 device.
> 
> Signed-off-by: Daniel Henrique Barboza <danielhb413@gmail.com>
> ---
>   hw/pci-host/pnv_phb4.c     | 75 +++++++++++++++++++++++++++++++++++++-
>   hw/pci-host/pnv_phb4_pec.c |  5 +++
>   hw/ppc/pnv.c               |  2 +
>   3 files changed, 80 insertions(+), 2 deletions(-)
> 
> diff --git a/hw/pci-host/pnv_phb4.c b/hw/pci-host/pnv_phb4.c
> index 3ffa8f51e9..10f8d6a919 100644
> --- a/hw/pci-host/pnv_phb4.c
> +++ b/hw/pci-host/pnv_phb4.c
> @@ -1487,15 +1487,86 @@ static void pnv_phb4_instance_init(Object *obj)
>       object_initialize_child(obj, "source", &phb->xsrc, TYPE_XIVE_SOURCE);
>   }
>   
> +static PnvPhb4PecStack *pnv_phb4_get_stack(int chip_id, int index,
> +                                           Error **errp)
> +{
> +    PnvMachineState *pnv = PNV_MACHINE(qdev_get_machine());
> +    PnvChip *chip = pnv_get_chip(pnv, chip_id);
> +    Pnv9Chip *chip9 = PNV9_CHIP(chip);
> +    int i, j;
> +
> +    for (i = 0; i < chip->num_pecs; i++) {
> +        /*
> +         * For each PEC, check the amount of stacks it supports
> +         * and see if the given phb4 index matches a stack.
> +         */
> +        PnvPhb4PecState *pec = &chip9->pecs[i];
> +
> +        for (j = 0; j < pec->num_stacks; j++) {
> +            if (index == pnv_phb4_pec_get_phb_id(pec, j)) {
> +                return &pec->stacks[j];
> +            }
> +        }
> +    }
> +
> +    error_setg(errp,
> +               "pnv-phb4 chip-id %d index %d didn't match any existing PEC",
> +               chip_id, index);
> +
> +    return NULL;
> +}
> +
>   static void pnv_phb4_realize(DeviceState *dev, Error **errp)
>   {
>       PnvPHB4 *phb = PNV_PHB4(dev);
>       PCIHostState *pci = PCI_HOST_BRIDGE(dev);
>       XiveSource *xsrc = &phb->xsrc;
> +    Error *local_err = NULL;
>       int nr_irqs;
>       char name[32];
>   
> -    assert(phb->stack);
> +    /* User created PHB */
> +    if (!phb->stack) {
> +        PnvMachineState *pnv = PNV_MACHINE(qdev_get_machine());
> +        PnvChip *chip = pnv_get_chip(pnv, phb->chip_id);

Arg. my comment on the pnv_phb4_get_stack() prototype was clearly
a mistake ! We are calling twice pnv_get_chip() to get the chip
and there is no reason for it.

Can you changed it back ? Sorry about that ... You can flame me.

> +        PnvPhb4PecClass *pecc;
> +        BusState *s;
> +
> +        if (!chip) {
> +            error_setg(errp, "invalid chip id: %d", phb->chip_id);
> +            return;
> +        }
> +
> +        phb->stack = pnv_phb4_get_stack(phb->chip_id, phb->phb_id,
> +                                        &local_err);
> +        if (local_err) {
> +            error_propagate(errp, local_err);
> +            return;
> +        }
> +
> +        /* All other phb properties but 'version' are already set */
> +        pecc = PNV_PHB4_PEC_GET_CLASS(phb->stack->pec);
> +        object_property_set_int(OBJECT(phb), "version", pecc->version,
> +                                &error_fatal);

Yes :/ This version is a constant and should probably be a class attribute.

I am not sure we need a property anymore. we could change pnv_phb4_reg_read()
with :
    
    switch (off) {
    case PHB_VERSION:
         return PNV_PHB4_PEC_GET_CLASS(phb->stack->pec)->version;


Another small problem to handle is the root port type :

     /* Add a single Root port if running with defaults */
     if (defaults_enabled()) {
         pnv_phb_attach_root_port(PCI_HOST_BRIDGE(phb),
                                  TYPE_PNV_PHB4_ROOT_PORT);
     }


With PHB5, we should use another type. This can come later.

> +
> +        /*
> +         * Assign stack->phb since pnv_phb4_update_regions() uses it
> +         * to access the phb.
> +         */
> +        phb->stack->phb = phb;
> +
> +        /*
> +         * Reparent user created devices to the chip to build
> +         * correctly the device tree.
> +         */
> +        pnv_chip_parent_fixup(chip, OBJECT(phb), phb->phb_id);
> +
> +        s = qdev_get_parent_bus(DEVICE(chip));
> +        if (!qdev_set_parent_bus(DEVICE(phb), s, &local_err)) {
> +            error_propagate(errp, local_err);
> +            return;
> +        }
> +    }
>   
>       pnv_phb4_XSCOM_init(phb);
>   
> @@ -1600,7 +1671,7 @@ static void pnv_phb4_class_init(ObjectClass *klass, void *data)
>       dc->realize         = pnv_phb4_realize;
>       device_class_set_props(dc, pnv_phb4_properties);
>       set_bit(DEVICE_CATEGORY_BRIDGE, dc->categories);
> -    dc->user_creatable  = false;
> +    dc->user_creatable  = true;
>   
>       xfc->notify         = pnv_phb4_xive_notify;
>   }
> diff --git a/hw/pci-host/pnv_phb4_pec.c b/hw/pci-host/pnv_phb4_pec.c
> index d4c52a5d28..dfd25831d5 100644
> --- a/hw/pci-host/pnv_phb4_pec.c
> +++ b/hw/pci-host/pnv_phb4_pec.c
> @@ -19,6 +19,7 @@
>   #include "hw/pci/pci_bus.h"
>   #include "hw/ppc/pnv.h"
>   #include "hw/qdev-properties.h"
> +#include "sysemu/sysemu.h"
>   
>   #include <libfdt.h>
>   
> @@ -282,6 +283,10 @@ static void pnv_pec_stk_realize(DeviceState *dev, Error **errp)
>       PnvPhb4PecClass *pecc = PNV_PHB4_PEC_GET_CLASS(pec);
>       int phb_id = pnv_phb4_pec_get_phb_id(pec, stack->stack_no);
>   
> +    if (!defaults_enabled()) {> +        return;

May be move all the code doing the PHB4 device realize in a helper routine
and call it under if (defaults_enabled()) { ... }

Thanks,

C.


> +    }
> +
>       stack->phb = PNV_PHB4(qdev_new(TYPE_PNV_PHB4));
>
>       object_property_set_int(OBJECT(stack->phb), "chip-id", pec->chip_id,
> diff --git a/hw/ppc/pnv.c b/hw/ppc/pnv.c
> index fe7e67e73a..837146a2fb 100644
> --- a/hw/ppc/pnv.c
> +++ b/hw/ppc/pnv.c
> @@ -1960,6 +1960,8 @@ static void pnv_machine_power9_class_init(ObjectClass *oc, void *data)
>       pmc->compat = compat;
>       pmc->compat_size = sizeof(compat);
>       pmc->dt_power_mgt = pnv_dt_power_mgt;
> +
> +    machine_class_allow_dynamic_sysbus_dev(mc, TYPE_PNV_PHB4);
>   }
>   
>   static void pnv_machine_power10_class_init(ObjectClass *oc, void *data)
>