linux-kernel - Re: [RFC FIX PATCH] x86/e820: Stop kernel boot when RAM resource reservation fails

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Date:   Thu, 4 Aug 2022 11:46:35 +0200
From:   Ingo Molnar <mingo@...nel.org>
To:     Bharata B Rao <bharata@....com>
Cc:     Borislav Petkov <bp@...en8.de>, linux-kernel@...r.kernel.org,
        tglx@...utronix.de, mingo@...hat.com, x86@...nel.org,
        dave.hansen@...ux.intel.com, nikunj@....com, hpa@...or.com,
        Abraham.Shaju@....com
Subject: Re: [RFC FIX PATCH] x86/e820: Stop kernel boot when RAM resource
 reservation fails


* Bharata B Rao <bharata@....com> wrote:

> On 7/18/2022 8:37 PM, Borislav Petkov wrote:
> > 
> > I betcha you can generate a lot of "kernel bugs" with weird qemu
> > options. If it is not a real use case, nobody cares.
> 
> I see that we will hit this problem by default when starting
> a guest with 1T or more memory using QEMU.
> 
> > 
> > And even if it were a real use case, panicking the machine is not the
> > right fix.
> 
> I couldn't see a clean exit/recovery option in 
> setup_arch()->e820__reserve_resources() where this happens. Any 
> suggestions?

I'd emit a low impact, non-fatal WARN()ing to make sure users aren't silent 
victims of an easily detectable firmware (Qemu) misconfiguration.

Thanks,

	Ingo