Re: [RFC PATCH 2/5] hw/arm/smmuv3: Add initial support for SMMUv3 Nested device

[Eric Auger]

Hi Shameer,

On 11/28/24 09:28, Shameerali Kolothum Thodi wrote:
>
>> -----Original Message-----
>> From: Eric Auger <eric.auger@redhat.com>
>> Sent: Thursday, November 28, 2024 8:07 AM
>> To: Zhangfei Gao <zhangfei.gao@linaro.org>
>> Cc: Jason Gunthorpe <jgg@nvidia.com>; Shameerali Kolothum Thodi
>> <shameerali.kolothum.thodi@huawei.com>; Donald Dutile
>> <ddutile@redhat.com>; Nicolin Chen <nicolinc@nvidia.com>; qemu-
>> arm@nongnu.org; qemu-devel@nongnu.org; peter.maydell@linaro.org;
>> Linuxarm <linuxarm@huawei.com>; Wangzhou (B)
>> <wangzhou1@hisilicon.com>; jiangkunkun <jiangkunkun@huawei.com>;
>> Jonathan Cameron <jonathan.cameron@huawei.com>
>> Subject: Re: [RFC PATCH 2/5] hw/arm/smmuv3: Add initial support for
>> SMMUv3 Nested device
>>
>>
>>
>> On 11/28/24 04:25, Zhangfei Gao wrote:
>>> Hi, Eric
>>>
>>> On Thu, 28 Nov 2024 at 00:06, Eric Auger <eric.auger@redhat.com> wrote:
>>>
>>>>> Yeah, there is no live migration support yet in the SMMU qmeu driver,
>>>>> AFAIK?
>>>> the non accelerated SMMU QEMU device does support migration.
>>> Could you clarify more about this?
>>> The migration is not supported if using viommu (SMMU QEMU device),
>> isn't it?
>> No this is not correct. Current QEMU SMMU device *does* support
>> migration (see VMStateDescription) as well as qemu virtio-iommu device.
>> so for instance if you run a guest with smmuv3 and protected virtio-pci
>> devices this is supposed to be migratable. If it does not work this is
>> bug and this should be fixed ;-)
> I think if I am right Zhangfei was testing with vfio-pci device assigned on 
> his vSVA
> branch. But migration with vfio device is currently explicitly blocked if 
> vIOMMU is
> present. 
definitively I was talking about migration vSMMU/VFIO which is not upstream.
>
> I think Joao is working on it here[1].
>
> But we may require additional support when we have vSVA to handle any
> in-flight page fault handling gracefully.
>
> Thanks,
> Shameer
> 1. 
> https://lore.kernel.org/all/20230622214845.3980-1-joao.m.martins@oracle.com/
Thanks

Eric
>
>
>