linux-kernel - Re: [RFC PATCH] kexec, x86/boot: map systab region in identity mapping before accessing it

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Message-ID: <20190426101635.GQ3584@localhost.localdomain>
Date:   Fri, 26 Apr 2019 18:16:35 +0800
From:   Baoquan He <bhe@...hat.com>
To:     Borislav Petkov <bp@...en8.de>
Cc:     "H. Peter Anvin" <hpa@...or.com>,
        Junichi Nomura <j-nomura@...jp.nec.com>, dyoung@...hat.com,
        Kairui Song <kasong@...hat.com>,
        Thomas Gleixner <tglx@...utronix.de>,
        linux-kernel@...r.kernel.org, Chao Fan <fanc.fnst@...fujitsu.com>,
        "x86@...nel.org" <x86@...nel.org>,
        "kexec@...ts.infradead.org" <kexec@...ts.infradead.org>
Subject: Re: [RFC PATCH] kexec, x86/boot: map systab region in identity
 mapping before accessing it

On 04/26/19 at 11:58am, Borislav Petkov wrote:
> On Fri, Apr 26, 2019 at 05:51:34PM +0800, Baoquan He wrote:
> > I can make a patch to add a bit into xloadflags, to indicate that this
> > is kexec-ed kernel. It can help to differentiate kexec-ed kernel from
> > kdump kernel.
> 
> From the recent snafu, the only thing we needed is to differentiate
> between the *first* kernel and the following kernel(s) which has been
> started/loaded using a kexec syscall.

OK. To make sure I got it, the loader type 0xD is enough for this, right? 

It's fine to me, we can add it later if needed. I remember there's an
issue in intel/amd iommu, in which we need differentiate between
kexec/kdump kernel, but not very sure. I will check it when I have time
to work on that.

Thanks
Baoquan