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SubjectRe: [PATCH v5 3/3] x86/tdx: Add Quote generation support

On 5/3/22 3:24 PM, Dave Hansen wrote:
> On 5/2/22 18:27, Kirill A. Shutemov wrote:
>>> Again, Dave and Andi already commented you should use vmap() to avoid breaking
>>> up the direct-mapping. Please use vmap() instead.
>>> Will review the rest later.
>> I would rather convert it to use DMA API for memory allocation. It will
>> tap into swiotlb buffer that already converted and there's no need to
>> touch direct mapping. Both allocation and freeing such memory is cheaper
>> because of that.
> Sathya, I don't quite understand why you are so forcefully declining to
> incorporate review feedback on this point. I gave very specific
> feedback about the kind of mapping you need and that you should avoid
> fragmenting the direct map if at all possible.
> Why is this code still fragmenting the direct map?

I have already implemented it and testing it now.

In this discussion, we are comparing the use of DMA API for memory
allocation vs vmap/sharing it in driver itself.

Sathyanarayanan Kuppuswamy
Linux Kernel Developer

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