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SubjectRe: [RFC PATCH V3 08/11] swiotlb: Add bounce buffer remap address setting function
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On 2021-06-07 07:43, Christoph Hellwig wrote:
> On Sun, May 30, 2021 at 11:06:25AM -0400, Tianyu Lan wrote:
>> From: Tianyu Lan <Tianyu.Lan@microsoft.com>
>>
>> For Hyper-V isolation VM with AMD SEV SNP, the bounce buffer(shared memory)
>> needs to be accessed via extra address space(e.g address above bit39).
>> Hyper-V code may remap extra address space outside of swiotlb. swiotlb_
>> bounce() needs to use remap virtual address to copy data from/to bounce
>> buffer. Add new interface swiotlb_set_bounce_remap() to do that.
>
> Why can't you use the bus_dma_region ranges to remap to your preferred
> address?

FWIW, I think a better generalisation for this would be allowing
set_memory_decrypted() to return an address rather than implicitly
operating in-place, and hide all the various hypervisor hooks behind that.

Robin.

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