Re: [PATCH 11/24] pnv/phb4: Bury unwanted "pnv-phb4-pec-stack" devices

From: Greg Kurz <groug@kaod.org>
To: Markus Armbruster <armbru@redhat.com>
Cc: berrange@redhat.com, ehabkost@redhat.com, qemu-devel@nongnu.org,
	qemu-ppc@nongnu.org, "Cédric Le Goater" <clg@kaod.org>,
	pbonzini@redhat.com, "David Gibson" <david@gibson.dropbear.id.au>
Subject: Re: [PATCH 11/24] pnv/phb4: Bury unwanted "pnv-phb4-pec-stack" devices
Date: Mon, 18 May 2020 10:49:06 +0200	[thread overview]
Message-ID: <20200518104906.5faec091@bahia.lan> (raw)
In-Reply-To: <20200518050408.4579-12-armbru@redhat.com>

On Mon, 18 May 2020 07:03:55 +0200
Markus Armbruster <armbru@redhat.com> wrote:

> The number of stacks is controlled by property "num-stacks".
> pnv_pec_instance_init() creates the maximum supported number, because
> the property has not been set then.  pnv_pec_realize() realizes only
> the wanted number.  Works, although it can leave unrealized devices
> hanging around in the QOM composition tree.  Affects machine powernv9.
> 
> Bury the unwanted devices by making pnv_pec_realize() unparent them.
> Visible in "info qom-tree":
> 
>      /machine (powernv9-machine)
>        /chip[0] (power9_v2.0-pnv-chip)
>          [...]
>          /pec[0] (pnv-phb4-pec)
>            /stack[0] (pnv-phb4-pec-stack)
>              [...]
>     -      /stack[1] (pnv-phb4-pec-stack)
>     -        /phb (pnv-phb4)
>     -          /pcie-mmcfg-mmio[0] (qemu:memory-region)
>     -          /root (pnv-phb4-root-port)
>     -          /source (xive-source)
>     -      /stack[2] (pnv-phb4-pec-stack)
>     -        /phb (pnv-phb4)
>     -          /pcie-mmcfg-mmio[0] (qemu:memory-region)
>     -          /root (pnv-phb4-root-port)
>     -          /source (xive-source)
>            /xscom-pec-0.0-nest[0] (qemu:memory-region)
>            /xscom-pec-0.0-pci[0] (qemu:memory-region)
>          /pec[1] (pnv-phb4-pec)
>            /stack[0] (pnv-phb4-pec-stack)
>              [...]
>            /stack[1] (pnv-phb4-pec-stack)
>              [...]
>     -      /stack[2] (pnv-phb4-pec-stack)
>     -        /phb (pnv-phb4)
>     -          /pcie-mmcfg-mmio[0] (qemu:memory-region)
>     -          /root (pnv-phb4-root-port)
>     -          /source (xive-source)
>            /xscom-pec-0.1-nest[0] (qemu:memory-region)
>            /xscom-pec-0.1-pci[0] (qemu:memory-region)
>          /pec[2] (pnv-phb4-pec)
>            /stack[0] (pnv-phb4-pec-stack)
>              [...]
>            /stack[1] (pnv-phb4-pec-stack)
>              [...]
>            /stack[2] (pnv-phb4-pec-stack)
>              [...]
> 
> Cc: Cédric Le Goater <clg@kaod.org>
> Cc: David Gibson <david@gibson.dropbear.id.au>
> Cc: qemu-ppc@nongnu.org
> Signed-off-by: Markus Armbruster <armbru@redhat.com>
> ---

Makes sense :)

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

>  hw/pci-host/pnv_phb4_pec.c | 3 +++
>  1 file changed, 3 insertions(+)
> 
> diff --git a/hw/pci-host/pnv_phb4_pec.c b/hw/pci-host/pnv_phb4_pec.c
> index 911d147ffd..565345a018 100644
> --- a/hw/pci-host/pnv_phb4_pec.c
> +++ b/hw/pci-host/pnv_phb4_pec.c
> @@ -397,6 +397,9 @@ static void pnv_pec_realize(DeviceState *dev, Error **errp)
>              return;
>          }
>      }
> +    for (; i < PHB4_PEC_MAX_STACKS; i++) {
> +        object_unparent(OBJECT(&pec->stacks[i]));
> +    }
>  
>      /* Initialize the XSCOM regions for the PEC registers */
>      snprintf(name, sizeof(name), "xscom-pec-%d.%d-nest", pec->chip_id,