Re: [PATCH Part1 RFC v3 20/22] x86/boot: Add Confidential Computing address to setup_header

Michael Roth
2021-06-24T12:35:36Z

On Thu, Jun 24, 2021 at 09:27:41AM +0200, Borislav Petkov wrote:
> On Wed, Jun 23, 2021 at 10:19:11PM -0500, Michael Roth wrote:
> > One downside to this is we still need something in the boot protocol,
> > either via setup_data, or setup_header directly.
>
> Huh, now I'm confused. You gave the acpi_rsdp_addr example and I thought
> that should be enough, that's why I suggested boot_params.

Well, that's enough for the boot/compressed->uncompressed parameter
passing, but would a bootloader be allowed to use that same approach to
pass in the CC blob (for things like non-EFI/containers)? I was under the
impression that for that case we'd still want something in
setup_header/setup_data for bootloaders to use, and that using boot_params
directly is more of a legacy/ad-hoc thing. Is that accurate?

>
> Maybe you should point me to the code which does what you need so that I
> can get a better idea...
>
> > Having it in setup_header avoids the need to also have to add a field
> > to boot_params for the boot/compressed->uncompressed passing, but
> > maybe that's not a good enough justification. Perhaps if the TDX folks
> > have similar needs though.
>
> Yes, reportedly they do so I guess the solution should be
> vendor-agnostic. Let's see what they need first.

Ok, good to know.

>
> Thx.
>
> --
> Regards/Gruss,
> Boris.
>
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