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Re: [PATCH v11 05/11] vfio/migration: Block multiple devices migration
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From: |
Jason Gunthorpe |
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Subject: |
Re: [PATCH v11 05/11] vfio/migration: Block multiple devices migration |
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Date: |
Tue, 16 May 2023 13:11:30 -0300 |
On Tue, May 16, 2023 at 02:35:21PM +0000, Shameerali Kolothum Thodi wrote:
> Ok. Got it. So it depends on what SMMU does for that mapping and is not
> related to migration per se and has the potential to crash the system if
> SMMU go ahead with that memory access. Isn't it a more generic problem
> then when we have multiple devices attached to the VM?
It is, and I am hoping to solve it when I get P2P support into iommufd
> I need to check if there is anything in SMMU spec that forbids this
> access.
There isn't, it is up to the integration how it handles 'hairpin'
traffic. A good implementation will work correctly as Intel and other
CPUs do. A very bad implementation will crash. Medium is to return
error tlps.
Jason