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Re: [PATCH] vhost: Unbreak SMMU and virtio-iommu on dev-iotlb support
From: |
Auger Eric |
Subject: |
Re: [PATCH] vhost: Unbreak SMMU and virtio-iommu on dev-iotlb support |
Date: |
Mon, 8 Feb 2021 21:30:56 +0100 |
User-agent: |
Mozilla/5.0 (X11; Linux x86_64; rv:78.0) Gecko/20100101 Thunderbird/78.6.0 |
Hi,
[Adding David and Greg in CC]
On 2/8/21 7:37 PM, Peter Xu wrote:
> On Mon, Feb 08, 2021 at 11:21:23AM +0800, Jason Wang wrote:
>
> [...]
>
>>> I'm not sure I remember it right, but we seem to have similar discussion
>>> previously on "what if the user didn't specify ats=on" - I think at that
>>> time
>>> the conclusion was that we ignore the failure since that's not a valid
>>> configuration for qemu.
>>
>>
>> Yes, but I think I was wrong at that time.
>
> I can't say you're wrong - I actually still agree with you that at least
> there's a priority of things we'd do, and this one is not extremely important
> if that's not a major use case (say, if you will 100% always suggest an user
> to
> use ats=on for a viommu enabled vhost).
>
>>>
>>> The other issue I'm worried is (I think I mentioned it somewhere, but just
>>> to
>>> double confirm): I'd like to make sure SMMU and virtio-iommu are the only
>>> IOMMU
>>> platform that will use vhost.
>>
>>
>> For upstream, it won't be easy :)
>
> Sorry I definitely didn't make myself clear... :)
>
> To be explicit, does ppc use vhost kernel too? Since I know at least ppc has
> its own translation unit and its iommu notifier in qemu, so I'm unsure whether
> the same patch would break ppc too, because vhost could also ignore all UNMAP
> sent by the ppc vIOMMU.
>
>>
>>
>>> Otherwise IIUC we need to fix those vIOMMUs too.
>>
>>
>> Right, last time I check AMD IOMMU emulation, it simply trigger device IOTLB
>> invalidation during IOTLB invalidation which looks wrong.
>
> I did quickly grep IOMMU_NOTIFIER_UNMAP in amd_iommu.c and saw nothing. It
> seems amd iommu is not ready for any kind of IOMMU notifiers yet.
for context, we experienced a regression with vsmmuv3/vhost and
virtio-iommu/vhost integration. We wondered whether the ppc viommu is
able to protect vhost devices and if this relies on legacy
IOMMU_NOTIFIER_UNMAP notifiers. ie. vhost does not register this
notifier anymore but instead register dev-iotlb unmap notifier.
Thanks
Eric
>
> Thanks,
>
- Re: [PATCH] vhost: Unbreak SMMU and virtio-iommu on dev-iotlb support, (continued)
- Re: [PATCH] vhost: Unbreak SMMU and virtio-iommu on dev-iotlb support, Jason Wang, 2021/02/04
- Re: [PATCH] vhost: Unbreak SMMU and virtio-iommu on dev-iotlb support, Auger Eric, 2021/02/05
- Re: [PATCH] vhost: Unbreak SMMU and virtio-iommu on dev-iotlb support, Peter Xu, 2021/02/05
- RE: [PATCH] vhost: Unbreak SMMU and virtio-iommu on dev-iotlb support, Tian, Kevin, 2021/02/07
- Re: [PATCH] vhost: Unbreak SMMU and virtio-iommu on dev-iotlb support, Peter Xu, 2021/02/07
- RE: [PATCH] vhost: Unbreak SMMU and virtio-iommu on dev-iotlb support, Tian, Kevin, 2021/02/08
- Re: [PATCH] vhost: Unbreak SMMU and virtio-iommu on dev-iotlb support, Peter Xu, 2021/02/08
- Re: [PATCH] vhost: Unbreak SMMU and virtio-iommu on dev-iotlb support, Auger Eric, 2021/02/08
- Re: [PATCH] vhost: Unbreak SMMU and virtio-iommu on dev-iotlb support, Jason Wang, 2021/02/07
- Re: [PATCH] vhost: Unbreak SMMU and virtio-iommu on dev-iotlb support, Peter Xu, 2021/02/08
- Re: [PATCH] vhost: Unbreak SMMU and virtio-iommu on dev-iotlb support,
Auger Eric <=
- Re: [PATCH] vhost: Unbreak SMMU and virtio-iommu on dev-iotlb support, Jason Wang, 2021/02/08
- Re: [PATCH] vhost: Unbreak SMMU and virtio-iommu on dev-iotlb support, Auger Eric, 2021/02/09
- Re: [PATCH] vhost: Unbreak SMMU and virtio-iommu on dev-iotlb support, Peter Xu, 2021/02/09