Re: [RFC PATCH 09/11] x86/microcode: Expose EUPDATESVN procedure via sysfs

[Borislav Petkov <bp@alien8.de>]

On Wed, Mar 09, 2022 at 07:42:21AM -0800, Dave Hansen wrote:
> There's a little bit in the cover letter that _implies_ why EUPDATESVN
> isn't called during the actual microcode update:
> 
> > This series implements the infrastructure needed to track and tear
> > down bare-metal enclaves and then run EUPDATESVN. This is expected
> > to be triggered by administrators via sysfs at some convenient time
> > after a microcode update, probably by the microcode update tooling
> > itself.
> 
> This allows the (non-destructive) ucode update and the destructive
> EUPDATESVN procedure to happen at different times.

Which means, that this has even less to do with the microcode loader.
That whole glue can be somewhere in arch/x86/...sgx/ land and be
completely independent.

> If we just want to make the ucode update itself call EUPDATESVN via
> microcode_check(), that makes the ucode update itself destructive to SGX
> enclaves.  That's not the end of the world, but this series is going to
> some amount of trouble (including new ABI) to avoid it.
> 
> Perhaps we need to hear more about why this is so much of an issue.

Yah, it all sounds weird.

-- 
Regards/Gruss,
    Boris.

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