RE: [PATCH v4 6/7] hw/arm/virt: Allow user-creatable SMMUv3 dev instantiation

[Shameerali Kolothum Thodi via <qemu-arm@nongnu.org>]

> -----Original Message-----
> From: Nicolin Chen <nicolinc@nvidia.com>
> Sent: Monday, June 16, 2025 6:31 AM
> To: Shameerali Kolothum Thodi <shameerali.kolothum.thodi@huawei.com>
> Cc: qemu-arm@nongnu.org; qemu-devel@nongnu.org;
> eric.auger@redhat.com; peter.maydell@linaro.org; jgg@nvidia.com;
> ddutile@redhat.com; berrange@redhat.com; imammedo@redhat.com;
> nathanc@nvidia.com; mochs@nvidia.com; smostafa@google.com; Linuxarm
> <linuxarm@huawei.com>; Wangzhou (B) <wangzhou1@hisilicon.com>;
> jiangkunkun <jiangkunkun@huawei.com>; Jonathan Cameron
> <jonathan.cameron@huawei.com>; zhangfei.gao@linaro.org
> Subject: Re: [PATCH v4 6/7] hw/arm/virt: Allow user-creatable SMMUv3 dev
> instantiation
> 
> On Fri, Jun 13, 2025 at 03:44:48PM +0100, Shameer Kolothum wrote:
> > Allow cold-plug of smmuv3 device to virt if there is no machine
> > wide legacy smmuv3 or a virtio-iommu is specified.
> >
> > Device tree support for new smmuv3 dev is limited to the case where
> > it is associated with the default pcie.0 RC.
> 
> I forgot the detail for this limitation. Maybe spare a few more
> words briefly describing why?

Qemu lacks support for presenting PCI device tree bindings for the primary
PCIe bus and PXB bus instances completely.

Please see the details here:
https://lore.kernel.org/qemu-devel/20230421165037.2506-1-Jonathan.Cameron@huawei.com/

I will add bit more description here to make it more clear.

> 
> > Tested-by: Nathan Chen <nathanc@nvidia.com>
> > Signed-off-by: Shameer Kolothum
> <shameerali.kolothum.thodi@huawei.com>
> 
> Reviewed-by: Nicolin Chen <nicolinc@nvidia.com>

Thanks,
Shameer