From: Kairui Song <kasong@redhat.com>
To: Junichi Nomura <j-nomura@ce.jp.nec.com>
Cc: "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
Borislav Petkov <bp@alien8.de>,
Thomas Gleixner <tglx@linutronix.de>,
Chao Fan <fanc.fnst@cn.fujitsu.com>, Baoquan He <bhe@redhat.com>,
Dave Young <dyoung@redhat.com>, "x86@kernel.org" <x86@kernel.org>,
"kexec@lists.infradead.org" <kexec@lists.infradead.org>
Subject: Re: [PATCH] x86/kexec: always ensure EFI systab region is mapped
Date: Tue, 23 Apr 2019 10:15:09 -0700 [thread overview]
Message-ID: <CACPcB9d-oNvp1Kag1J8X+QBdgqfU0ps1OztjOk8n=Pw2G6ONWA@mail.gmail.com> (raw)
In-Reply-To: <965f770a-b103-72fb-eaef-cb337ebe8290@ce.jp.nec.com>
On Mon, Apr 22, 2019 at 11:21 PM Junichi Nomura <j-nomura@ce.jp.nec.com> wrote:
>
> On 4/22/19 6:28 PM, Kairui Song wrote:
> > The reason is the systab region is not mapped by the identity mapping
> > provided by kexec. Currently kexec only create identity mapping for
> > mem regions, wihch won't cover the systab. So second kernel will be
> > accessing a not mapped memory region and cause fault.
> > But as kexec tend to pad the map region up to PUD size, the
> > systab could be included in the map by accident, so it worked on
> > some machines, but that will be broken easily and unstable.
>
> Is the mapping of ACPI tables just by luck, too?
>
Good question, they should have same issue with systab, I ignored this one.
Then in first kernel when doing kexec it should ensure both ACPI
tables and the EFI systab are mapped, that should cover everything and
make it work.
Is there anything else missing?
--
Best Regards,
Kairui Song
next prev parent reply other threads:[~2019-04-23 17:15 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-04-22 9:28 [PATCH] x86/kexec: always ensure EFI systab region is mapped Kairui Song
2019-04-23 6:20 ` Junichi Nomura
2019-04-23 10:49 ` Dave Young
2019-04-23 17:15 ` Kairui Song [this message]
2019-04-24 2:47 ` Junichi Nomura
2019-04-24 5:41 ` Baoquan He
2019-04-24 6:18 ` Dave Young
2019-04-24 7:45 ` Baoquan He
2019-04-24 11:36 ` Kairui Song
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