Re: [PATCH v10 2/9] fw_cfg: Refactor extra pci roots addition

[Philippe Mathieu-Daudé]

On 19/11/20 02:48, Jiahui Cen wrote:
> Extract extra pci roots addition from pc machine, which could be used by
> other machines.
>
> In order to make uefi get the extra roots, it is necessary to write extra
> roots into fw_cfg. And only if the uefi knows there are extra roots,
> the config spaces of devices behind the root could be obtained.
>
> Signed-off-by: Jiahui Cen <cenjiahui@huawei.com>
> Signed-off-by: Yubo Miao <miaoyubo@huawei.com>
> ---
>   hw/i386/pc.c              | 18 +--------------
>   hw/nvram/fw_cfg.c         | 23 ++++++++++++++++++++
>   include/hw/nvram/fw_cfg.h |  9 ++++++++
>   3 files changed, 33 insertions(+), 17 deletions(-)


> diff --git a/hw/nvram/fw_cfg.c b/hw/nvram/fw_cfg.c
> index 08539a1aab..282ba93e2e 100644
> --- a/hw/nvram/fw_cfg.c
> +++ b/hw/nvram/fw_cfg.c
> @@ -40,6 +40,7 @@
>   #include "qemu/cutils.h"
>   #include "qapi/error.h"
>   #include "hw/acpi/aml-build.h"
> +#include "hw/pci/pci_bus.h"

Stumbling at this (now merged as commit 0abd38885ac), not
sure how we let PCI stuff mixed within this generic device.
We have TYPE_FW_CFG_DATA_GENERATOR_INTERFACE to avoid that.

>   #define FW_CFG_FILE_SLOTS_DFLT 0x20
>   
> @@ -1061,6 +1062,28 @@ bool fw_cfg_add_from_generator(FWCfgState *s, const char *filename,
>       return true;
>   }
>   
> +void fw_cfg_add_extra_pci_roots(PCIBus *bus, FWCfgState *s)
> +{
> +    int extra_hosts = 0;
> +
> +    if (!bus) {
> +        return;
> +    }
> +
> +    QLIST_FOREACH(bus, &bus->child, sibling) {
> +        /* look for expander root buses */
> +        if (pci_bus_is_root(bus)) {
> +            extra_hosts++;
> +        }
> +    }
> +
> +    if (extra_hosts && s) {
> +        uint64_t *val = g_malloc(sizeof(*val));
> +        *val = cpu_to_le64(extra_hosts);
> +        fw_cfg_add_file(s, "etc/extra-pci-roots", val, sizeof(*val));
> +    }
> +}
> +
>   static void fw_cfg_machine_reset(void *opaque)
>   {
>       MachineClass *mc = MACHINE_GET_CLASS(qdev_get_machine());