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Date:   Wed, 21 Jul 2021 16:33:55 +0200
From:   Christoph Hellwig <hch@lst.de>
To:     Tianyu Lan <ltykernel@gmail.com>
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Subject: Re: [Resend RFC PATCH V4 09/13] x86/Swiotlb/HV: Add Swiotlb bounce
 buffer remap function for HV IVM
Message-ID: <20210721143355.GA10848@lst.de>
References: <20210707154629.3977369-1-ltykernel@gmail.com> <20210707154629.3977369-10-ltykernel@gmail.com> <20210720135437.GA13554@lst.de> <8f1a285d-4b67-8041-d326-af565b2756c0@gmail.com>
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On Wed, Jul 21, 2021 at 06:28:48PM +0800, Tianyu Lan wrote:
> dma_mmap_attrs() and dma_get_sgtable_attrs() get input virtual address
> belonging to backing memory with struct page and returns bounce buffer
> dma physical address which is below shared_gpa_boundary(vTOM) and passed
> to Hyper-V via vmbus protocol.
>
> The new map virtual address is only to access bounce buffer in swiotlb
> code and will not be used other places. It's stored in the mem->vstart.
> So the new API set_memory_decrypted_map() in this series is only called
> in the swiotlb code. Other platforms may replace set_memory_decrypted()
> with set_memory_decrypted_map() as requested.

It seems like you are indeed not using these new helpers in
dma_direct_alloc.  How is dma_alloc_attrs/dma_alloc_coherent going to
work on these systems?