On Tue, Aug 31, 2021 at 06:22:44PM +0200, Borislav Petkov wrote:

On Fri, Aug 27, 2021 at 01:32:40PM -0500, Michael Roth wrote:

quoted

If the memory is allocated in boot/compressed/mem_encrypt.S, wouldn't
kernel proper still need to create a static buffer for its copy?

Just like the other variables like sme_me_mask etc that file allocates
at the bottom. Or do you have a better idea?

What did you think of the suggestion of defining it in sev-shared.c
as a static buffer/struct as __ro_after_init? It would be nice to
declare/reserve the memory in one place. Another benefit is it doesn't
need to be exported, and could just be local with all the other
snp_cpuid* helpers that access it in sev-shared.c

quoted

Would that be a reasonable approach for v6?

I don't like the ifdeffery one bit, TBH. I guess you should split it
and have a boot/compressed page and a kernel proper one and keep 'em
separate. That should make everything nice and clean at the cost of 2*4K
which is nothing nowadays.

I think I can address the ifdeffery by splitting the boot/proper routines
into separate self-contained routines (and maybe move them out into
boot/compressed/sev.c and kernel/sev.c, respectively), then having them
just initialize the table pointer and create the copy using a common setter
function, e.g.

  snp_cpuid_table_create(cc_blob, fixup_offset)

and for boot/compressed.c fixup_offset would just be passed in as 0.

Thx.

-- 
Regards/Gruss,
    Boris.

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