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From: Andy Lutomirski <luto@amacapital.net>
To: Borislav Petkov <bp@alien8.de>
Cc: Linus Torvalds <torvalds@linux-foundation.org>,
	"H. Peter Anvin" <hpa@zytor.com>,
	Andy Lutomirski <luto@kernel.org>, X86 ML <x86@kernel.org>,
	Paolo Bonzini <pbonzini@redhat.com>,
	Peter Zijlstra <peterz@infradead.org>,
	KVM list <kvm@vger.kernel.org>,
	Arjan van de Ven <arjan@linux.intel.com>,
	xen-devel <Xen-devel@lists.xen.org>,
	"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
	Andrew Morton <akpm@linux-foundation.org>
Subject: Re: [PATCH v5 4/9] x86/traps: Enable all exception handler callbacks early
Date: Mon, 4 Apr 2016 08:47:44 -0700	[thread overview]
Message-ID: <CALCETrXcLdrLaOFWEPqRXHEnzAKy8sJG7s+jJFcpkbcAdAAheQ@mail.gmail.com> (raw)
In-Reply-To: <20160403141041.GE19007@pd.tnic>

On Sun, Apr 3, 2016 at 7:10 AM, Borislav Petkov <bp@alien8.de> wrote:
> On Sun, Apr 03, 2016 at 06:55:00AM -0700, Andy Lutomirski wrote:
>> > No, please don't fail at early boot.
>> >
>> > Early boot is just about the *worst* situation to try to debug odd
>> > failures, exactly since things like printk may not be reliable, and
>> > things won't get logged etc.
>> >
>> > So particularly during early boot we should try as hard as possible
>> > not to crash - even if it means not being able to log about a problem.
>> > At least that way you have a hopefully working machine and can *maybe*
>> > debug things.
>> >
>>
>> In this regard, at least, my patch is the right approach.  Calling the
>> handler, whatever it is, is less likely to panic than refusing to call
>> it.
>
> Ok, good.
>
> But can we pretty please document this whole situation, i.e., the
> fact that we're trying really really hard not to fail early boot for
> debuggability reasons - either in the commit message or better in the
> code, for future reference. I think this is an important aspect to hold
> down.

I emailed out a followup patch to add a comment.

--Andy

>
> Thanks.
>
> --
> Regards/Gruss,
>     Boris.
>
> ECO tip #101: Trim your mails when you reply.



-- 
Andy Lutomirski
AMA Capital Management, LLC

  parent reply	other threads:[~2016-04-04 15:48 UTC|newest]

Thread overview: 101+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2016-04-02 14:01 [PATCH v5 0/9] Improve non-"safe" MSR access failure handling Andy Lutomirski
2016-04-02 14:01 ` [PATCH v5 1/9] x86/head: Pass a real pt_regs and trapnr to early_fixup_exception Andy Lutomirski
2016-04-02 14:01   ` Andy Lutomirski
2016-04-13 11:43   ` [tip:x86/asm] x86/head: Pass a real pt_regs and trapnr to early_fixup_exception() tip-bot for Andy Lutomirski
2016-04-13 11:43   ` tip-bot for Andy Lutomirski
2016-04-02 14:01 ` [PATCH v5 2/9] x86/head: Move the early NMI fixup into C Andy Lutomirski
2016-04-02 14:01 ` Andy Lutomirski
2016-04-13 11:43   ` [tip:x86/asm] " tip-bot for Andy Lutomirski
2016-04-13 11:43   ` tip-bot for Andy Lutomirski
2016-04-02 14:01 ` [PATCH v5 3/9] x86/head: Move early exception panic code into early_fixup_exception Andy Lutomirski
2016-04-02 14:01   ` Andy Lutomirski
2016-04-02 18:39   ` Borislav Petkov
2016-04-02 18:39   ` Borislav Petkov
2016-04-02 20:13     ` Andy Lutomirski
2016-04-02 20:47       ` Borislav Petkov
2016-04-02 20:47       ` Borislav Petkov
2016-04-02 20:58         ` Andy Lutomirski
2016-04-02 20:58         ` Andy Lutomirski
2016-04-04 11:52           ` Jan Kara
2016-04-04 11:52           ` Jan Kara
2016-04-04 12:46             ` Peter Zijlstra
2016-04-04 12:46             ` Peter Zijlstra
2016-04-04 15:32             ` Andy Lutomirski
2016-04-04 15:36               ` Arjan van de Ven
2016-04-04 15:36               ` Arjan van de Ven
2016-04-04 16:00               ` Peter Zijlstra
2016-04-04 16:00               ` Peter Zijlstra
2016-04-04 19:38                 ` Borislav Petkov
2016-04-04 19:38                 ` Borislav Petkov
2016-04-04 21:31                   ` Andy Lutomirski
2016-04-04 21:40                     ` Borislav Petkov
2016-04-04 21:40                     ` Borislav Petkov
2016-04-04 21:31                   ` Andy Lutomirski
2016-04-04 15:32             ` Andy Lutomirski
2016-04-02 20:13     ` Andy Lutomirski
2016-04-13 11:44   ` [tip:x86/asm] x86/head: Move early exception panic code into early_fixup_exception() tip-bot for Andy Lutomirski
2016-04-13 11:44   ` tip-bot for Andy Lutomirski
2016-04-02 14:01 ` [PATCH v5 4/9] x86/traps: Enable all exception handler callbacks early Andy Lutomirski
2016-04-02 18:52   ` Borislav Petkov
2016-04-02 20:16     ` Andy Lutomirski
2016-04-02 20:52       ` Borislav Petkov
2016-04-02 20:52       ` Borislav Petkov
2016-04-03  8:07         ` Borislav Petkov
2016-04-03  8:07         ` Borislav Petkov
2016-04-03 13:22           ` Andy Lutomirski
2016-04-03 13:22           ` Andy Lutomirski
2016-04-03 13:51           ` Linus Torvalds
2016-04-03 13:51           ` Linus Torvalds
2016-04-03 13:55             ` Andy Lutomirski
2016-04-03 14:10               ` Borislav Petkov
2016-04-03 14:10               ` Borislav Petkov
2016-04-04 15:47                 ` Andy Lutomirski
2016-04-04 15:47                 ` Andy Lutomirski [this message]
2016-04-03 14:17               ` Linus Torvalds
2016-04-03 14:17               ` Linus Torvalds
2016-04-03 13:55             ` Andy Lutomirski
2016-04-02 20:16     ` Andy Lutomirski
2016-04-02 18:52   ` Borislav Petkov
2016-04-13 11:44   ` [tip:x86/asm] " tip-bot for Andy Lutomirski
2016-04-13 11:44   ` tip-bot for Andy Lutomirski
2016-04-02 14:01 ` [PATCH v5 4/9] " Andy Lutomirski
2016-04-02 14:01 ` [PATCH v5 5/9] x86/paravirt: Add _safe to the read_msr and write_msr PV hooks Andy Lutomirski
2016-04-02 14:01   ` Andy Lutomirski
2016-04-03  8:41   ` Borislav Petkov
2016-04-03 13:23     ` Andy Lutomirski
2016-04-03 14:07       ` Borislav Petkov
2016-04-03 14:07       ` Borislav Petkov
2016-04-03 13:23     ` Andy Lutomirski
2016-04-03  8:41   ` Borislav Petkov
2016-04-13 11:44   ` [tip:x86/asm] x86/paravirt: Add _safe to the read_ms()r and write_msr() PV callbacks tip-bot for Andy Lutomirski
2016-04-13 11:44   ` tip-bot for Andy Lutomirski
2016-04-02 14:01 ` [PATCH v5 6/9] x86/msr: Carry on after a non-"safe" MSR access fails Andy Lutomirski
2016-04-02 14:01 ` Andy Lutomirski
2016-04-13 11:45   ` [tip:x86/asm] " tip-bot for Andy Lutomirski
2016-04-13 11:45   ` tip-bot for Andy Lutomirski
2016-04-02 14:01 ` [PATCH v5 7/9] x86/paravirt: Add paravirt_{read, write}_msr Andy Lutomirski
2016-04-02 14:01 ` [PATCH v5 7/9] x86/paravirt: Add paravirt_{read,write}_msr Andy Lutomirski
2016-04-04 16:33   ` [PATCH v5 7/9] x86/paravirt: Add paravirt_{read, write}_msr David Vrabel
2016-04-04 16:33   ` [Xen-devel] " David Vrabel
2016-04-04 16:40     ` Andy Lutomirski
2016-04-04 16:40     ` Andy Lutomirski
2016-04-13 11:45   ` [tip:x86/asm] x86/paravirt: Add paravirt_{read, write}_msr() tip-bot for Andy Lutomirski
2016-04-13 11:45   ` [tip:x86/asm] x86/paravirt: Add paravirt_{read,write}_msr() tip-bot for Andy Lutomirski
2016-04-02 14:01 ` [PATCH v5 8/9] x86/paravirt: Make "unsafe" MSR accesses unsafe even if PARAVIRT=y Andy Lutomirski
2016-04-02 14:01   ` Andy Lutomirski
2016-04-13 11:46   ` [tip:x86/asm] " tip-bot for Andy Lutomirski
2016-04-13 11:46   ` tip-bot for Andy Lutomirski
2016-04-02 14:01 ` [PATCH v5 9/9] x86/msr: Set the return value to zero when native_rdmsr_safe fails Andy Lutomirski
2016-04-13 11:46   ` [tip:x86/asm] x86/msr: Set the return value to zero when native_rdmsr_safe() fails tip-bot for Andy Lutomirski
2016-04-13 11:46   ` tip-bot for Andy Lutomirski
2016-04-02 14:01 ` [PATCH v5 9/9] x86/msr: Set the return value to zero when native_rdmsr_safe fails Andy Lutomirski
2016-04-02 14:24 ` [PATCH v5 0/9] Improve non-"safe" MSR access failure handling Linus Torvalds
2016-04-02 15:13   ` Andy Lutomirski
2016-04-02 15:21     ` Linus Torvalds
2016-04-02 15:21     ` Linus Torvalds
2016-04-02 15:13   ` Andy Lutomirski
2016-04-02 14:24 ` Linus Torvalds
2016-04-04 16:23 ` Borislav Petkov
2016-04-04 16:23 ` Borislav Petkov
2016-04-05 15:38 ` Boris Ostrovsky
2016-04-05 15:38 ` [Xen-devel] " Boris Ostrovsky

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