linux-kernel - Re: [PATCH] x86/efi: update e820 about reserved EFI boot services data to fix kexec breakage

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Message-ID: <20191204100917.GC114697@gmail.com>
Date:   Wed, 4 Dec 2019 11:09:17 +0100
From:   Ingo Molnar <mingo@...nel.org>
To:     Dave Young <dyoung@...hat.com>
Cc:     linux-efi@...r.kernel.org, x86@...nel.org,
        linux-kernel@...r.kernel.org,
        Michael Weiser <michael@...ser.dinsnail.net>,
        Ard Biesheuvel <ard.biesheuvel@...aro.org>,
        kexec@...ts.infradead.org, Ingo Molnar <mingo@...hat.com>,
        Borislav Petkov <bp@...en8.de>,
        "Eric W. Biederman" <ebiederm@...ssion.com>,
        "H. Peter Anvin" <hpa@...or.com>,
        Thomas Gleixner <tglx@...utronix.de>
Subject: Re: [PATCH] x86/efi: update e820 about reserved EFI boot services
 data to fix kexec breakage


* Dave Young <dyoung@...hat.com> wrote:

> On 12/04/19 at 03:52pm, Dave Young wrote:
> > Michael Weiser reported he got below error during a kexec rebooting:
> > esrt: Unsupported ESRT version 2904149718861218184.
> > 
> > The ESRT memory stays in EFI boot services data, and it was reserved
> > in kernel via efi_mem_reserve().  The initial purpose of the reservation
> > is to reuse the EFI boot services data across kexec reboot. For example
> > the BGRT image data and some ESRT memory like Michael reported. 
> > 
> > But although the memory is reserved it is not updated in X86 e820 table.
> > And kexec_file_load iterate system ram in io resource list to find places
> > for kernel, initramfs and other stuff. In Michael's case the kexec loaded
> > initramfs overwritten the ESRT memory and then the failure happened.
> 
> s/overwritten/overwrote :)  If need a repost please let me know..

No need, I've edited the typo. :)

Thanks,

	Ingo