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Message-ID: <6be29d38-5c93-7cc9-0de7-235d3f83773c@intel.com>
Date: Thu, 23 Jun 2022 10:23:59 -0700
From: Dave Hansen <dave.hansen@...el.com>
To: "Kirill A. Shutemov" <kirill.shutemov@...ux.intel.com>,
Borislav Petkov <bp@...en8.de>,
Andy Lutomirski <luto@...nel.org>,
Sean Christopherson <seanjc@...gle.com>,
Andrew Morton <akpm@...ux-foundation.org>,
Joerg Roedel <jroedel@...e.de>,
Ard Biesheuvel <ardb@...nel.org>
Cc: Andi Kleen <ak@...ux.intel.com>,
Kuppuswamy Sathyanarayanan
<sathyanarayanan.kuppuswamy@...ux.intel.com>,
David Rientjes <rientjes@...gle.com>,
Vlastimil Babka <vbabka@...e.cz>,
Tom Lendacky <thomas.lendacky@....com>,
Thomas Gleixner <tglx@...utronix.de>,
Peter Zijlstra <peterz@...radead.org>,
Paolo Bonzini <pbonzini@...hat.com>,
Ingo Molnar <mingo@...hat.com>,
Varad Gautam <varad.gautam@...e.com>,
Dario Faggioli <dfaggioli@...e.com>,
Mike Rapoport <rppt@...nel.org>,
David Hildenbrand <david@...hat.com>,
marcelo.cerri@...onical.com, tim.gardner@...onical.com,
khalid.elmously@...onical.com, philip.cox@...onical.com,
x86@...nel.org, linux-mm@...ck.org, linux-coco@...ts.linux.dev,
linux-efi@...r.kernel.org, linux-kernel@...r.kernel.org,
Eric Biederman <ebiederm@...ssion.com>,
kexec@...ts.infradead.org
Subject: Re: [PATCHv7 11/14] x86: Disable kexec if system has unaccepted
memory
... adding kexec folks
On 6/14/22 05:02, Kirill A. Shutemov wrote:
> On kexec, the target kernel has to know what memory has been accepted.
> Information in EFI map is out of date and cannot be used.
>
> boot_params.unaccepted_memory can be used to pass the bitmap between two
> kernels on kexec, but the use-case is not yet implemented.
>
> Disable kexec on machines with unaccepted memory for now.
...
> +static int __init unaccepted_init(void)
> +{
> + if (!boot_params.unaccepted_memory)
> + return 0;
> +
> +#ifdef CONFIG_KEXEC_CORE
> + /*
> + * TODO: Information on memory acceptance status has to be communicated
> + * between kernel.
> + */
> + pr_warn("Disable kexec: not yet supported on systems with unaccepted memory\n");
> + kexec_load_disabled = 1;
> +#endif
This looks to be the *only* in-kernel user tweaking kexec_load_disabled.
It doesn't feel great to just be disabling kexec like this. Why not
just fix it properly?
What do the kexec folks think?
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