Re: [RFC PATCH v3 11/20] x86: Add support for changing memory encryption attribute

[Borislav Petkov]

On Sat, Nov 19, 2016 at 12:48:27PM -0600, Tom Lendacky wrote:
> Should I move this functionality into the sme_set_mem_* functions or
> remove the sme_set_mem_* functions and use the set_memory_* functions
> directly.  The latter means calculating the number of pages, but makes
> it clear that this works on a page level while the former keeps
> everything the mem_encrypt.c file (and I can change that to take in a
> page count so that it is clear about the page boundary usage).

A user of that interface doesn't care, right?

All she wants to do is pass in an address and size and the code will
figure out everything. And I think address and size is the simplest two
args you can pass. numpages can be calculated from it. As you do in
sme_set_mem_*.

And you need to do it all in pageattr.c because it uses the cpa wankery
in there so you probably want to define

int set_memory_dec(unsigned long addr, size_t size)
int set_memory_enc(unsigned long addr, size_t size)

there which both simply call

__set_memory_enc_dec(unsigned long addr, size_t size, bool enc)

and it goes and figures out everything, builds the cpa_data and does the
mapping.

That looks very simple and clean to me.

-- 
Regards/Gruss,
    Boris.

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