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From: Dave Young <dyoung@redhat.com>
To: Junichi Nomura <j-nomura@ce.jp.nec.com>
Cc: "x86@kernel.org" <x86@kernel.org>,
	Kairui Song <kasong@redhat.com>, Baoquan He <bhe@redhat.com>,
	Chao Fan <fanc.fnst@cn.fujitsu.com>,
	"kexec@lists.infradead.org" <kexec@lists.infradead.org>,
	"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
	Borislav Petkov <bp@alien8.de>,
	Thomas Gleixner <tglx@linutronix.de>
Subject: Re: [PATCH] x86/kexec: always ensure EFI systab region is mapped
Date: Tue, 23 Apr 2019 18:49:24 +0800	[thread overview]
Message-ID: <20190423104924.GA1730@dhcp-128-65.nay.redhat.com> (raw)
In-Reply-To: <965f770a-b103-72fb-eaef-cb337ebe8290@ce.jp.nec.com>

On 04/23/19 at 06:20am, Junichi Nomura 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?

Hmm, guess it should be mapped by luck, here is the range on the T420: 
da99f000 - dae9efff Reserved (efi systab fall in this region)
daf9f000 - daffefff ACPI tables

Thanks
Dave

_______________________________________________
kexec mailing list
kexec@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/kexec

WARNING: multiple messages have this Message-ID (diff)
From: Dave Young <dyoung@redhat.com>
To: Junichi Nomura <j-nomura@ce.jp.nec.com>
Cc: Kairui Song <kasong@redhat.com>,
	"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>,
	"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 18:49:24 +0800	[thread overview]
Message-ID: <20190423104924.GA1730@dhcp-128-65.nay.redhat.com> (raw)
In-Reply-To: <965f770a-b103-72fb-eaef-cb337ebe8290@ce.jp.nec.com>

On 04/23/19 at 06:20am, Junichi Nomura 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?

Hmm, guess it should be mapped by luck, here is the range on the T420: 
da99f000 - dae9efff Reserved (efi systab fall in this region)
daf9f000 - daffefff ACPI tables

Thanks
Dave

  reply	other threads:[~2019-04-23 10:49 UTC|newest]

Thread overview: 18+ 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
2019-04-22  9:28 ` Kairui Song
2019-04-23  6:20 ` Junichi Nomura
2019-04-23  6:20   ` Junichi Nomura
2019-04-23 10:49   ` Dave Young [this message]
2019-04-23 10:49     ` Dave Young
2019-04-23 17:15   ` Kairui Song
2019-04-23 17:15     ` Kairui Song
2019-04-24  2:47     ` Junichi Nomura
2019-04-24  2:47       ` Junichi Nomura
2019-04-24  5:41       ` Baoquan He
2019-04-24  5:41         ` Baoquan He
2019-04-24  6:18         ` Dave Young
2019-04-24  6:18           ` Dave Young
2019-04-24  7:45           ` Baoquan He
2019-04-24  7:45             ` Baoquan He
2019-04-24 11:36             ` Kairui Song
2019-04-24 11:36               ` Kairui Song

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