xen-devel.lists.xenproject.org archive mirror
 help / color / mirror / Atom feed
From: Ingo Molnar <mingo@kernel.org>
To: Andy Lutomirski <luto@amacapital.net>
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: Thu, 1 Oct 2015 09:15:06 +0200	[thread overview]
Message-ID: <20151001071505.GA21542__49108.0043874264$1443683814$gmane$org@gmail.com> (raw)
In-Reply-To: <CALCETrVMV2_3ywQ_t+0rsqzxMm6D9PvDEmOdrie67rRzfj-W_Q@mail.gmail.com>


* 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.

Thanks,

	Ingo

  parent reply	other threads:[~2015-10-01  7:15 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 [this message]
     [not found]                 ` <20151001071505.GA21542@gmail.com>
2016-03-11 16:48                   ` Andy Lutomirski
     [not found]                   ` <CALCETrUFakwGL9zpj9TwKX9KbG9czq8fpEViU3nWaCvnpGurew@mail.gmail.com>
2016-03-12 16:02                     ` Ingo Molnar
2015-09-30 18:32           ` H. Peter Anvin

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to='20151001071505.GA21542__49108.0043874264$1443683814$gmane$org@gmail.com' \
    --to=mingo@kernel.org \
    --cc=Xen-devel@lists.xen.org \
    --cc=akpm@linux-foundation.org \
    --cc=arjan@linux.intel.com \
    --cc=kvm@vger.kernel.org \
    --cc=linux-kernel@vger.kernel.org \
    --cc=luto@amacapital.net \
    --cc=pbonzini@redhat.com \
    --cc=peterz@infradead.org \
    --cc=tglx@linutronix.de \
    --cc=torvalds@linux-foundation.org \
    --cc=x86@kernel.org \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line before the message body. 
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).