Re: [PATCH 02/17] pnv_phb3.c: do not set 'root-bus' as bus name

From: "Cédric Le Goater" <clg@kaod.org>
To: Daniel Henrique Barboza <danielhb413@gmail.com>, <qemu-devel@nongnu.org>
Cc: qemu-ppc@nongnu.org, david@gibson.dropbear.id.au
Subject: Re: [PATCH 02/17] pnv_phb3.c: do not set 'root-bus' as bus name
Date: Mon, 3 Jan 2022 09:25:23 +0100	[thread overview]
Message-ID: <0a0b7ad2-b8ef-44bb-7d41-f977666202a9@kaod.org> (raw)
In-Reply-To: <20211228193806.1198496-3-danielhb413@gmail.com>

On 12/28/21 20:37, Daniel Henrique Barboza wrote:
> All pnv-phb3-root-bus buses are being created as 'root-bus'. This
> makes it impossible to, for example, add a pnv-phb3-root-port in
> a specific root bus, since they all have the same name. By default
> the device will be parented by the pnv-phb3 device that precedeced it in
> the QEMU command line.
> 
> Moreover, this doesn't all for custom bus naming. Libvirt, for instance,
> likes to name these buses as 'pcie.N', where 'N' is the index value of
> the controller in the domain XML, by using the 'id' command line
> attribute. At this moment this is also being ignored - the created root
> bus will always be named 'root-bus'.
> 
> This patch fixes both scenarios by removing the 'root-bus' name from the
> pci_register_root_bus() call. If an "id" is provided, use that.
> Otherwise use 'NULL' as bus name. The 'NULL' value will be handled in
> qbus_init_internal() and it will defaulted as lowercase bus type + the
> global bus_id value.
> 
> After this path we can define the bus name by using the 'id' attribute:
> 
> qemu-system-ppc64 -m 4G -machine powernv8,accel=tcg \
>      -device pnv-phb3,chip-id=0,index=1,id=pcie.0
> 
>    dev: pnv-phb3, id "pcie.0"
>      index = 1 (0x1)
>      chip-id = 0 (0x0)
>      x-config-reg-migration-enabled = true
>      bypass-iommu = false
>      bus: pcie.0
>        type pnv-phb3-root-bus
> 
> And without an 'id' we will have the following default:
> 
> qemu-system-ppc64 -m 4G -machine powernv8,accel=tcg \
>      -device pnv-phb3,chip-id=0,index=1
> 
>    dev: pnv-phb3, id ""
>      index = 1 (0x1)
>      chip-id = 0 (0x0)
>      x-config-reg-migration-enabled = true
>      bypass-iommu = false
>      bus: pnv-phb3-root-bus.0
>        type pnv-phb3-root-bus
> 
> Signed-off-by: Daniel Henrique Barboza <danielhb413@gmail.com>

Reviewed-by: Cédric Le Goater <clg@kaod.org>

Thanks,

C.


> ---
>   hw/pci-host/pnv_phb3.c | 3 ++-
>   1 file changed, 2 insertions(+), 1 deletion(-)
> 
> diff --git a/hw/pci-host/pnv_phb3.c b/hw/pci-host/pnv_phb3.c
> index 130d392b3e..f1b1f109a3 100644
> --- a/hw/pci-host/pnv_phb3.c
> +++ b/hw/pci-host/pnv_phb3.c
> @@ -1064,7 +1064,8 @@ static void pnv_phb3_realize(DeviceState *dev, Error **errp)
>       memory_region_init(&phb->pci_mmio, OBJECT(phb), "pci-mmio",
>                          PCI_MMIO_TOTAL_SIZE);
>   
> -    pci->bus = pci_register_root_bus(dev, "root-bus",
> +    pci->bus = pci_register_root_bus(dev,
> +                                     dev->id ? dev->id : NULL,
>                                        pnv_phb3_set_irq, pnv_phb3_map_irq, phb,
>                                        &phb->pci_mmio, &phb->pci_io,
>                                        0, 4, TYPE_PNV_PHB3_ROOT_BUS);
>