Re: [PATCH v2 5/6] platform/x86: intel_tdx_attest: Add TDX Guest attestation interface driver

On 7/12/21 5:33 PM, Kuppuswamy, Sathyanarayanan wrote:

On 7/8/21 5:38 PM, Andi Kleen wrote:

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Expensive and permanently fractures the direct map.

I'm struggling to figure out why the direct map is even touched
here.

I think Sathya did it this way because the TD interface requires a 
physical address.

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Why not just use a vmalloc area mapping?  You really just need
*a* decrypted mapping to the page.  You don't need to make
*every* mapping to the page decrypted.

Yes it would be possible to use vmap() on the page and only set
the vmap encrypted by passing the right flags directly.

Is it alright to have non coherent mappings? If yes, any
documentation reference for it?

Do you mean non-cache-coherent mappings?  I'm not sure what that has to
do with creating "unencrypted" (shared) mappings.

Are you asking exactly which arguments to pass to vmap() or to vmap_pfn()?