Re: [PATCH 3/5] hyperv/IOMMU: Enable swiotlb bounce buffer for Isolation VM

[Tianyu Lan <ltykernel@gmail.com>]

On 11/17/2021 10:00 PM, Tianyu Lan wrote:
> On 11/17/2021 6:01 PM, Christoph Hellwig wrote:
>> This doesn't really have much to do with normal DMA mapping,
>> so why does this direct through the dma ops?
>>
> 
> According to the previous discussion, dma_alloc_noncontigous()
> and dma_vmap_noncontiguous() may be used to handle the noncontigous
> memory alloc/map in the netvsc driver. So add alloc/free and vmap/vunmap
> callbacks here to handle the case. The previous patch v4 & v5 handles
> the allocation and map in the netvsc driver. If this should not go 
> though dma ops, We also may make it as vmbus specific function and keep
> the function in the vmbus driver.
> 
> https://lkml.org/lkml/2021/9/28/51


Hi Christoph:
       Sorry to bother you. Could you have a look? Which solution do you
prefer? If we need to call dma_alloc/map_noncontigous() function in the
netvsc driver what patch 4 does. The Hyper-V specific implementation
needs to be hided in some callbacks and call these callback in the
dma_alloc/map_noncontigous(). I used dma ops here. If the allocation and
map operation should be Hyper-V specific function, we may put these
functions in the vmbus driver and other vmbus device drivers also may
reuse these functions if necessary.

Thanks.