linux-kernel - Re: [RFC PATCH V3 08/11] swiotlb: Add bounce buffer remap address setting function

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Date:   Mon, 12 Jul 2021 17:40:12 +0800
From:   Tianyu Lan <ltykernel@...il.com>
To:     Christoph Hellwig <hch@....de>, Robin Murphy <robin.murphy@....com>
Cc:     kys@...rosoft.com, haiyangz@...rosoft.com, sthemmin@...rosoft.com,
        wei.liu@...nel.org, decui@...rosoft.com, tglx@...utronix.de,
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Subject: Re: [RFC PATCH V3 08/11] swiotlb: Add bounce buffer remap address
 setting function

Hi Christoph and Robin:
      I introduced new interface set_memory_decrypted_map() to hide all
the hypervisor code behind it in the latest version. In current generic
code, only swiotlb bounce buffer needs to be decrypted and remapped in 
the same time and so keep set_memory_decrypted(). If there were more 
requests of set_memory_decrypted_map() for other platform, we may
replace set_memory_decrypted() step by step. Please have a look.
       https://lkml.org/lkml/2021/7/7/570

Thanks.

On 6/15/2021 11:24 PM, Tianyu Lan wrote:
> On 6/14/2021 11:32 PM, Christoph Hellwig wrote:
>> On Mon, Jun 14, 2021 at 02:49:51PM +0100, Robin Murphy wrote:
>>> 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.
>>
>> Yes, something like that would be a good idea.  As-is
>> set_memory_decrypted is a pretty horribly API anyway due to passing
>> the address as void, and taking a size parameter while it works in units
>> of pages.  So I'd very much welcome a major overhaul of this API.
>>
> 
> Hi Christoph and Robin:
>      Thanks for your suggestion. I will try this idea in the next 
> version. Besides make the address translation into set_memory_
> decrypted() and return address, do you want to make other changes to the 
> API in order to make it more reasonable(e.g size parameter)?
> 
> Thanks