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

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Message-ID: <be498c32-bed6-d31a-ae94-6006dd59ea1e@amd.com>
Date:   Mon, 18 Jul 2022 20:24:08 +0530
From:   Bharata B Rao <bharata@....com>
To:     Boris Petkov <bp@...en8.de>, linux-kernel@...r.kernel.org
Cc:     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



On 7/18/2022 4:12 PM, Boris Petkov wrote:
> On July 18, 2022 8:58:15 AM UTC, Bharata B Rao <bharata@....com> wrote:
>> Currently it is possible to start a guest with memory that
>> is beyond the addressable range of CPU. This can typically
>> be done by using QEMU without explicilty specifying the max
>> physical addressable bits (via phys-bits or host-phys-bits
>> options). In such cases QEMU will start the guest with more
>> than 1TB memory but would implicitly limit the phys-bits to 40.
> 
> Why does the upstream kernel care about some weird qemu guest configurations? 

It may be a weird guest configuration, but it looks like
a kernel bug exposed by QEMU.

Regards,
Bharata