On 5/9/25 10:18 AM, Shameerali Kolothum Thodi wrote:
>
>> -----Original Message-----
>> From: Daniel P. Berrangé <berra...@redhat.com>
>> Sent: Friday, May 9, 2025 9:14 AM
>> To: Shameerali Kolothum Thodi <shameerali.kolothum.th...@huawei.com>
>> Cc: Donald Dutile <ddut...@redhat.com>; Markus Armbruster
>> <arm...@redhat.com>; Shameer Kolothum via <qemu-
>> de...@nongnu.org>; qemu-...@nongnu.org; eric.au...@redhat.com;
>> peter.mayd...@linaro.org; j...@nvidia.com; nicol...@nvidia.com;
>> nath...@nvidia.com; mo...@nvidia.com; smost...@google.com; Linuxarm
>> <linux...@huawei.com>; Wangzhou (B) <wangzh...@hisilicon.com>;
>> jiangkunkun <jiangkun...@huawei.com>; Jonathan Cameron
>> <jonathan.came...@huawei.com>; zhangfei....@linaro.org
>> Subject: Re: [PATCH v2 1/6] hw/arm/smmuv3: Add support to associate a
>> PCIe RC
>>
> [...]
>
>>>> - bus pcie, id=pcie.<num>
>>>> - device iommu=[intel_iommu|smmuv3|amd_iommu], bus=[sysbus |
>>>> pcie.<num>], id=iommu.<num>
>>>> [Yes, I'm sticking with 'iommu' as the generic naming... everyone thinks
>> of
>>>> device SMMUs as IOMMUs,
>>>> and QEMU should have a more arch-agnostic naming of these system
>>>> functions. ]
>>> Ok. But to circle back to what originally started this discussion—how
>> important
>>> is it to rely on the default "bus" in this case? As Markus pointed out,
>> SMMUv3
>>> is a platform device on the sysbus, so its default bus type can’t point to
>> something
>>> like PCIe. QEMU doesn’t currently support that.
>>>
>>> The main motivation for using the default "bus" so far has been to have
>> better
>>> compatibility with libvirt. Would libvirt be flexible enough if we switched
>> to using
>>> something like a "primary-bus" property instead?
>> Sorry if my previous comments misled you, when I previously talked about
>> linking via a "bus" property I was not considering the fact that "bus"
>> is a special property inside QEMU. From a libvirt POV we don't care what
>> the property is call - it was just intended to be a general illustration
>> of cross-referencing the iommu with the PCI bus it needed to be associated
>> with.
> Cool. That makes life easier 😊
Agreed ;-)
Eric
>
> Thanks,
> Shameer
