Messages in this thread | | | Subject | Re: [PATCH] vhost: introduce vDPA based backend | From | Zhu Lingshan <> | Date | Thu, 6 Feb 2020 11:21:27 +0800 |
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On 2/6/2020 11:11 AM, Jason Wang wrote: > > On 2020/2/5 下午9:14, Michael S. Tsirkin wrote: >> On Wed, Feb 05, 2020 at 08:56:48AM -0400, Jason Gunthorpe wrote: >>> On Wed, Feb 05, 2020 at 03:50:14PM +0800, Jason Wang wrote: >>>>> Would it be better for the map/umnap logic to happen inside each >>>>> device ? >>>>> Devices that needs the IOMMU will call iommu APIs from inside the >>>>> driver callback. >>>> Technically, this can work. But if it can be done by vhost-vpda it >>>> will make >>>> the vDPA driver more compact and easier to be implemented. >>> Generally speaking, in the kernel, it is normal to not hoist code of >>> out drivers into subsystems until 2-3 drivers are duplicating that >>> code. It helps ensure the right design is used >>> >>> Jason >> That's up to the sybsystem maintainer really, as there's also some >> intuition involved in guessing a specific API is widely useful. >> In-kernel APIs are flexible, if we find something isn't needed we just >> drop it. >> > > If I understand correctly. At least Intel (Ling Shan) and Brodcom > (Rob) doesn't want to deal with DMA stuffs in their driver. > > Anyway since the DMA bus operations is optional, driver may still > choose to do DMA by itself if they want even if it requires platform > IOMMU to work. > > Thanks > Many Thanks if this could be done. The parent device has DMA capabilities and dma ops implemented, we hope can make use of it, as discussed in the vdpa thread.
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