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Date:   Tue, 14 May 2019 16:09:16 +0200
From:   Ingo Molnar <mingo@kernel.org>
To:     Dave Young <dyoung@redhat.com>
Cc:     Peter Zijlstra <peterz@infradead.org>, Baoquan He <bhe@redhat.com>,
        Borislav Petkov <bp@alien8.de>, j-nomura@ce.jp.nec.com,
        kasong@redhat.com, fanc.fnst@cn.fujitsu.com, x86@kernel.org,
        kexec@lists.infradead.org, linux-kernel@vger.kernel.org,
        hpa@zytor.com, tglx@linutronix.de
Subject: Re: [PATCH v6 1/2] x86/kexec: Build identity mapping for EFI systab
 and ACPI tables
Message-ID: <20190514140916.GA90245@gmail.com>
References: <20190429135536.GC2324@zn.tnic>
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 <20190513073254.GB16774@MiWiFi-R3L-srv>
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 <20190514084841.GA27876@dhcp-128-65.nay.redhat.com>
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* Dave Young <dyoung@redhat.com> wrote:

> On 05/14/19 at 01:38pm, Peter Zijlstra wrote:
> > On Tue, May 14, 2019 at 04:48:41PM +0800, Dave Young wrote:
> > 
> > > > I did some tests on the laptop,  thing is:
> > > > 1. apply the 3 patches (two you posted + Boris's revert commit 52b922c3d49c)
> > > >    on latest Linus master branch, everything works fine.
> > > > 
> > > > 2. build and test the tip/next-merge-window branch, kernel hangs early
> > > > without output, (both 1st boot and kexec boot)
> > > 
> > > Update about 2.  It should be not early rsdp related, I got the boot log
> > > Since can not reproduce with Linus master branch it may have been fixed.
> > 
> > Nothing was changed here since PTI.
> > 
> > > [    0.685374][    T1] rcu: Hierarchical SRCU implementation.
> > > [    0.686414][    T1] general protection fault: 0000 [#1] SMP PTI
> > > [    0.687328][    T1] CPU: 0 PID: 1 Comm: swapper/0 Not tainted 5.1.0-rc6+ #877
> > > [    0.687328][    T1] Hardware name: LENOVO 4236NUC/4236NUC, BIOS 83ET82WW (1.52 ) 06/04/2018
> > > [    0.687328][    T1] RIP: 0010:reserve_ds_buffers+0x34e/0x450
> > 
> > > [    0.687328][    T1] Call Trace:
> > > [    0.687328][    T1]  ? hardlockup_detector_event_create+0x50/0x50
> > > [    0.687328][    T1]  x86_reserve_hardware+0x173/0x180
> > > [    0.687328][    T1]  x86_pmu_event_init+0x39/0x220
> > 
> > The DS buffers are special in that they're part of cpu_entrt_area. If
> > this comes apart it might mean your pagetables are dodgy.
> 
> Hmm, it seems caused by some WIP branch patches, I suspect below:
> commit 124d6af5a5f559e516ed2c6ea857e889ed293b43
> x86/paravirt: Standardize 'insn_buff' variable names

This commit had a bug which I fixed - could you try the latest -tip?

Thanks,

	Ingo