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From: Dave Young <dyoung@redhat.com>
To: Baoquan He <bhe@redhat.com>
Cc: linux-kernel@vger.kernel.org, tglx@linutronix.de,
	mingo@kernel.org, bp@alien8.de, hpa@zytor.com,
	kirill.shutemov@linux.intel.com, x86@kernel.org
Subject: Re: [PATCH v4 2/3] x86/kexec/64: Error out if try to jump to old 4-level kernel from 5-level kernel
Date: Wed, 22 May 2019 11:24:02 +0800	[thread overview]
Message-ID: <20190522032402.GA31575@dhcp-128-65.nay.redhat.com> (raw)
In-Reply-To: <20190522032029.GB31269@dhcp-128-65.nay.redhat.com>

On 05/22/19 at 11:20am, Dave Young wrote:
> On 05/09/19 at 09:36am, Baoquan He wrote:
> > If the running kernel has 5-level paging activated, the 5-level paging
> > mode is preserved across kexec. If the kexec'ed kernel does not contain
> > support for handling active 5-level paging mode in the decompressor, the
> > decompressor will crash with #GP.
> > 
> > Prevent this situation at load time. If 5-level paging is active, check the
> > xloadflags whether the kexec kernel can handle 5-level paging at least in
> > the decompressor. If not, reject the load attempt and print out error
> > message.
> > 
> > Signed-off-by: Baoquan He <bhe@redhat.com>
> > Acked-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
> > ---
> >  arch/x86/kernel/kexec-bzimage64.c | 5 +++++
> 
> How about the userspace kexec-tools?  It needs a similar detection, but
> I'm not sure how to detect paging mode, maybe some sysfs entry or
> vmcoreinfo in /proc/vmcore

meant /proc/kcore ...

Thanks
Dave

  reply	other threads:[~2019-05-22  3:24 UTC|newest]

Thread overview: 12+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-05-09  1:36 [PATCH v4 0/3] Add restrictions for kexec/kdump jumping between 5-level and 4-level kernel Baoquan He
2019-05-09  1:36 ` [PATCH v4 1/3] x86/boot: Add xloadflags bits for 5-level kernel checking Baoquan He
2019-05-09  1:36 ` [PATCH v4 2/3] x86/kexec/64: Error out if try to jump to old 4-level kernel from 5-level kernel Baoquan He
2019-05-09  7:01   ` Baoquan He
2019-05-09  7:02   ` [PATCH v5 " Baoquan He
2019-05-22  3:20   ` [PATCH v4 " Dave Young
2019-05-22  3:24     ` Dave Young [this message]
2019-05-22  4:50     ` Baoquan He
2019-05-09  1:36 ` [PATCH v4 3/3] x86/kdump/64: Change the upper limit of crashkernel reservation Baoquan He
2019-05-22  3:11   ` Dave Young
2019-05-22  3:15     ` Baoquan He
2019-05-23  3:15     ` Baoquan He

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