Re: [qemu-s390x] [PATCH v2 1/6] s390x/vfio: ap: Finding the AP bridge

[Tony Krowiak]

On 11/22/18 11:35 AM, Pierre Morel wrote:
> In the case we will enter QEMU through interception of instructions,
> we will need to retrieve the AP devices.
> The base device is the AP bridge.
>
> Let us implement a way to retrieve the AP Bridge from qtree.
>
> Signed-off-by: Pierre Morel <address@hidden>
> ---
>   hw/s390x/ap-bridge.c         | 12 ++++++++++++
>   include/hw/s390x/ap-bridge.h |  1 +
>   2 files changed, 13 insertions(+)
>
> diff --git a/hw/s390x/ap-bridge.c b/hw/s390x/ap-bridge.c
> index 3795d30..831ad5d 100644
> --- a/hw/s390x/ap-bridge.c
> +++ b/hw/s390x/ap-bridge.c
> @@ -14,6 +14,18 @@
>   #include "hw/s390x/ap-bridge.h"
>   #include "cpu.h"
>   
> +DeviceState *s390_get_ap_bridge(void)
> +{
> +    static DeviceState *apb;

Since you are caching a reference to the bridge after
retrieving it, why not make apb a global scope variable
and initialize it in s390_init_ap() when the bridge is
created. You can then declare it as an extern in the
ap-bridge.h header file and you eliminate the need for
this function. If you do make it a global var, I would
name it ap_bridge;

> +
> +    if (!apb) {
> +        apb = DEVICE(object_resolve_path(TYPE_AP_BRIDGE, NULL));
> +        assert(apb != NULL);
> +    }
> +
> +    return apb;
> +}

> +
>   static char *ap_bus_get_dev_path(DeviceState *dev)
>   {
>       /* at most one */
> diff --git a/include/hw/s390x/ap-bridge.h b/include/hw/s390x/ap-bridge.h
> index 470e439..dacb877 100644
> --- a/include/hw/s390x/ap-bridge.h
> +++ b/include/hw/s390x/ap-bridge.h
> @@ -15,5 +15,6 @@
>   #define TYPE_AP_BUS "ap-bus"
>   
>   void s390_init_ap(void);
> +DeviceState *s390_get_ap_bridge(void);
>   
>   #endif