From: Andy Lutomirski <luto@amacapital.net>
To: Ingo Molnar <mingo@kernel.org>
Cc: KVM list <kvm@vger.kernel.org>,
Peter Zijlstra <peterz@infradead.org>,
Linus Torvalds <torvalds@linux-foundation.org>,
the arch/x86 maintainers <x86@kernel.org>,
Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
xen-devel <Xen-devel@lists.xen.org>,
Paolo Bonzini <pbonzini@redhat.com>,
Thomas Gleixner <tglx@linutronix.de>,
Arjan van de Ven <arjan@linux.intel.com>,
Andrew Morton <akpm@linux-foundation.org>
Subject: Re: [PATCH v2 1/2] x86/msr: Carry on after a non-"safe" MSR access fails without !panic_on_oops
Date: Fri, 11 Mar 2016 08:48:09 -0800 [thread overview]
Message-ID: <CALCETrUFakwGL9zpj9TwKX9KbG9czq8fpEViU3nWaCvnpGurew__22345.1943522834$1457714991$gmane$org@mail.gmail.com> (raw)
In-Reply-To: <20151001071505.GA21542@gmail.com>
On Thu, Oct 1, 2015 at 12:15 AM, Ingo Molnar <mingo@kernel.org> wrote:
>
> * Andy Lutomirski <luto@amacapital.net> wrote:
>
>> > These could still be open coded in an inlined fashion, like the scheduler usage.
>>
>> We could have a raw_rdmsr for those.
>>
>> OTOH, I'm still not 100% convinced that this warn-but-don't-die behavior is
>> worth the effort. This isn't a frequent source of bugs to my knowledge, and we
>> don't try to recover from incorrect cr writes, out-of-bounds MMIO, etc, so do we
>> really gain much by rigging a recovery mechanism for rdmsr and wrmsr failures
>> for code that doesn't use the _safe variants?
>
> It's just the general principle really: don't crash the kernel on bootup. There's
> few things more user hostile than that.
>
> Also, this would maintain the status quo: since we now (accidentally) don't crash
> the kernel on distro kernels (but silently and unsafely ignore the faulting
> instruction), we should not regress that behavior (by adding the chance to crash
> again), but improve upon it.
Just a heads up: the extable improvements in tip:ras/core make it
straightforward to get the best of all worlds: explicit failure
handling (written in C!), no fast path overhead whatsoever, and no new
garbage in the exception handlers.
Patches coming once I test them.
>
> Thanks,
>
> Ingo
--
Andy Lutomirski
AMA Capital Management, LLC
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next prev parent reply other threads:[~2016-03-11 16:48 UTC|newest]
Thread overview: 22+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <cover.1442793572.git.luto@kernel.org>
2015-09-21 0:02 ` [PATCH v2 1/2] x86/msr: Carry on after a non-"safe" MSR access fails without !panic_on_oops Andy Lutomirski
2015-09-21 0:02 ` [PATCH v2 2/2] x86/msr: Set the return value to zero when native_rdmsr_safe fails Andy Lutomirski
[not found] ` <130a3b7ef4788baae3a6fe71293ab17442bc9a0a.1442793572.git.luto@kernel.org>
2015-09-21 0:15 ` [PATCH v2 1/2] x86/msr: Carry on after a non-"safe" MSR access fails without !panic_on_oops Linus Torvalds
[not found] ` <CA+55aFy4Chd-PJvxGne=TztPsvFqUG07Ht8mtc4+0oGNZNDOyw@mail.gmail.com>
2015-09-21 1:13 ` Andy Lutomirski
[not found] ` <CALCETrXqsKcqzfqMO2ctOJJ4X8Kb6vvoUpVDir9F2-a3XwK23w@mail.gmail.com>
2015-09-21 8:46 ` Ingo Molnar
[not found] ` <20150921084642.GA30984@gmail.com>
2015-09-21 12:27 ` Paolo Bonzini
2015-09-21 16:36 ` Linus Torvalds
[not found] ` <CA+55aFzKCi6pf0RP8HjDQYDsms6reB5AihuCAHEkVJtoOHk_Yw@mail.gmail.com>
2015-09-21 16:49 ` Arjan van de Ven
[not found] ` <56003506.1050100@linux.intel.com>
2015-09-21 17:27 ` Linus Torvalds
2015-09-21 17:43 ` Andy Lutomirski
[not found] ` <CALCETrUSEm_QLxGaBdmy3tQn=WnagvzTaYpy+i14sGUeaOUvTQ@mail.gmail.com>
2015-09-22 8:12 ` Paolo Bonzini
2015-09-21 18:16 ` Andy Lutomirski
[not found] ` <CALCETrUBcDxvtjKC-m97GPwCOHvcoDdGjnMJLukSue8ha55mng@mail.gmail.com>
2015-09-21 18:36 ` Borislav Petkov
2015-09-21 18:47 ` Linus Torvalds
2015-09-22 7:14 ` Ingo Molnar
2015-09-30 13:10 ` Peter Zijlstra
[not found] ` <20150930131002.GK2881@worktop.programming.kicks-ass.net>
2015-09-30 14:01 ` Ingo Molnar
[not found] ` <20150930140122.GB3285@gmail.com>
2015-09-30 18:04 ` Andy Lutomirski
[not found] ` <CALCETrVMV2_3ywQ_t+0rsqzxMm6D9PvDEmOdrie67rRzfj-W_Q@mail.gmail.com>
2015-10-01 7:15 ` Ingo Molnar
[not found] ` <20151001071505.GA21542@gmail.com>
2016-03-11 16:48 ` Andy Lutomirski [this message]
[not found] ` <CALCETrUFakwGL9zpj9TwKX9KbG9czq8fpEViU3nWaCvnpGurew@mail.gmail.com>
2016-03-12 16:02 ` Ingo Molnar
2015-09-30 18:32 ` H. Peter Anvin
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