linux-kernel - Re: [PATCH v6 1/2] x86/kexec: Build identity mapping for EFI systab and ACPI tables

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Date:   Tue, 21 May 2019 17:02:59 +0800
From:   Kairui Song <kasong@...hat.com>
To:     Junichi Nomura <j-nomura@...jp.nec.com>,
        Borislav Petkov <bp@...en8.de>
Cc:     "Rafael J. Wysocki" <rjw@...ysocki.net>,
        Baoquan He <bhe@...hat.com>,
        "dyoung@...hat.com" <dyoung@...hat.com>,
        "fanc.fnst@...fujitsu.com" <fanc.fnst@...fujitsu.com>,
        "x86@...nel.org" <x86@...nel.org>,
        "kexec@...ts.infradead.org" <kexec@...ts.infradead.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "hpa@...or.com" <hpa@...or.com>,
        "tglx@...utronix.de" <tglx@...utronix.de>
Subject: Re: [PATCH v6 1/2] x86/kexec: Build identity mapping for EFI systab
 and ACPI tables

On Wed, May 15, 2019 at 3:10 PM Junichi Nomura <j-nomura@...jp.nec.com> wrote:
>
> On 5/15/19 3:58 PM, Borislav Petkov wrote:
> > On Wed, May 15, 2019 at 05:17:19AM +0000, Junichi Nomura wrote:
> >> Hi Kairui,
> >>
> >> On 5/13/19 5:02 PM, Baoquan He wrote:
> >>> On 05/13/19 at 09:50am, Borislav Petkov wrote:
> >>>> On Mon, May 13, 2019 at 03:32:54PM +0800, Baoquan He wrote:
> >>>> So we're going to try it again this cycle and if there's no fallout, it
> >>>> will go upstream. If not, it will have to be fixed. The usual thing.
> >>>>
> >>>> And I don't care if Kairui's patch fixes this one problem - judging by
> >>>> the fragility of this whole thing, it should be hammered on one more
> >>>> cycle on as many boxes as possible to make sure there's no other SNAFUs.
> >>>>
> >>>> So go test it on more machines instead. I've pushed it here:
> >>>>
> >>>> https://git.kernel.org/pub/scm/linux/kernel/git/bp/bp.git/log/?h=next-merge-window
> >>>
> >>> Pingfan has got a machine to reproduce the kexec breakage issue, and
> >>> applying these two patches fix it. He planned to paste the test result.
> >>> I will ask him to try this branch if he has time, or I can get his
> >>> machine to test.
> >>>
> >>> Junichi, also have a try on Boris's branch in NEC's test environment?
> >>
> >> while the patch set works on most of the machines I'm testing around,
> >> I found kexec(1) fails to load kernel on a few machines if this patch
> >> is applied.  Those machines don't have IORES_DESC_ACPI_TABLES region
> >> and have ACPI tables in IORES_DESC_ACPI_NV_STORAGE region instead.
> >
> > Why? What kind of machines are those?
>
> I don't know.  They are just general purpose Xeon-based servers
> and not some special purpose machines.  So I guess there are other
> such machines in the wild.
>

Hi, I think it's reasonable to update the patch to include the
NV_STORAGE regions as well, most likely the firmware only provided
NV_STORAGE region? Can you help confirm if the e820 didn't contain
ACPI data, and only ACPI NVS?

I had a try with this update patch, it worked and didn't break anything.

Hi Boris, would you prefer to just fold Junichi update patch into the
previous one or I should send an updated patch?


--
Best Regards,
Kairui Song