Re: [PATCHv11.1 11/19] x86/tdx: Convert shared memory back to private on kexec

[Borislav Petkov]

On Tue, Jun 04, 2024 at 07:14:00PM +0300, Kirill A. Shutemov wrote:
> 			/*
> 			 * If tdx_enc_status_changed() fails, it leaves memory
> 			 * in an unknown state. If the memory remains shared,
> 			 * it can result in an unrecoverable guest shutdown on
> 			 * the first accessed through a private mapping.

"access"

So this sentence above can go too, right?

Because that comment is in tdx_kexec_finish() and we're basically going
off to kexec. So can a guest even access it through a private mapping?
We're shutting down so nothing is running anymore...

> 			 * The kdump kernel boot is not impacted as it uses
> 			 * a pre-reserved memory range that is always private.
> 			 * However, gathering crash information could lead to
> 			 * a crash if it accesses unconverted memory through
> 			 * a private mapping.

When does the kexec kernel even get such a private mapping? It is not
even up yet...

> 			 * pr_err() may assist in understanding such crashes.

"Print error info in order to leave bread crumbs for debugging." is what
I'd say.

Thx.

-- 
Regards/Gruss,
    Boris.

https://people.kernel.org/tglx/notes-about-netiquette