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Date:   Fri, 2 Jun 2023 18:09:00 +0200
From:   Borislav Petkov <bp@alien8.de>
To:     "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>
Cc:     Ard Biesheuvel <ardb@kernel.org>,
        Andy Lutomirski <luto@kernel.org>,
        Dave Hansen <dave.hansen@intel.com>,
        Sean Christopherson <seanjc@google.com>,
        Andrew Morton <akpm@linux-foundation.org>,
        Joerg Roedel <jroedel@suse.de>,
        Andi Kleen <ak@linux.intel.com>,
        Kuppuswamy Sathyanarayanan 
        <sathyanarayanan.kuppuswamy@linux.intel.com>,
        David Rientjes <rientjes@google.com>,
        Vlastimil Babka <vbabka@suse.cz>,
        Tom Lendacky <thomas.lendacky@amd.com>,
        Thomas Gleixner <tglx@linutronix.de>,
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        Paolo Bonzini <pbonzini@redhat.com>,
        Ingo Molnar <mingo@redhat.com>,
        Dario Faggioli <dfaggioli@suse.com>,
        Mike Rapoport <rppt@kernel.org>,
        David Hildenbrand <david@redhat.com>,
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        linux-efi@vger.kernel.org, linux-kernel@vger.kernel.org,
        Liam Merwick <liam.merwick@oracle.com>
Subject: Re: [PATCHv13 4/9] x86/boot/compressed: Handle unaccepted memory
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On Fri, Jun 02, 2023 at 06:36:44PM +0300, Kirill A. Shutemov wrote:
> I don't see why it is simpler. It looks unnecessary noisy to me.

Noisy?

I have no clue what you mean.

It is regular:

	if (bla && flu)

vs

	if (bla)
		return flu();

It is about having regular patterns which can be recognized at a quick
glance by those who get to stare at that code constantly.

> Configuration table suppose to be present, even if unaccepted memory is
> not supported. Something is very wrong if it is missing.

I am not sure if it is the decompressor's job to do such validation
- I guess this is something the EFI code should do.

> I will downgrade it warn().

Yes, or simply return here without accepting memory - plain and simple.

> I wanted to keep unaccepted_table private to the libstub/unaccepted_memory.c.
> The setter provides a good spot for documentation to guide unaccepted
> memory enablers for other archs.
> 
> Still want replace it with direct assignment?

No clue. Why would you want to keep a variable in the libstub private
which is not even in kernel proper, AFAICT?

> Okay, I will make init_unaccepted_memory() return true if unaccepted
> memory is present and hide defined it always-false for !UNACCEPTED_MEMORY.
> So this hunk will look this way:
> 
> 	if (init_unaccepted_memory()) {
> 		debug_putstr("Accepting memory... ");
> 		accept_memory(__pa(output), __pa(output) + needed_size);
> 	}

Yap, thanks.

-- 
Regards/Gruss,
    Boris.

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