From: Steven Rostedt <rostedt@goodmis.org>
To: Andy Lutomirski <luto@amacapital.net>
Cc: "Luck, Tony" <tony.luck@intel.com>,
Borislav Petkov <bp@alien8.de>,
Peter Zijlstra <peterz@infradead.org>,
Andy Lutomirski <luto@kernel.org>, x86-ml <x86@kernel.org>,
lkml <linux-kernel@vger.kernel.org>
Subject: Re: [RFC] #MC mess
Date: Tue, 18 Feb 2020 18:17:34 -0500 [thread overview]
Message-ID: <20200218181734.703038e1@gandalf.local.home> (raw)
In-Reply-To: <3CF4895A-5BCF-4E5C-B8D9-F9019DD02A12@amacapital.net>
On Tue, 18 Feb 2020 15:10:17 -0800
Andy Lutomirski <luto@amacapital.net> wrote:
> > On Feb 18, 2020, at 10:20 AM, Luck, Tony <tony.luck@intel.com> wrote:
> >
> >
> >>
> >> Anything else I'm missing? It is likely...
> >
> > + hw_breakpoint_disable();
> > + static_key_disable(&__tracepoint_read_msr.key);
> > + tracing_off();
> > +
> > ist_enter(regs);
> >
> > How about some code to turn all those back on for a recoverable (where we actually recovered) #MC?
> >
> >
>
>
> At the very least, in the user_mode(regs) case, tracing is fine.
Also, I don't think "tracing_off()" is what is wanted here. That just
disables writing to the ring buffer, which can be called in pretty much
any context (if it's before in_nmi() get's set, the worse thing that
happens is that events will get dropped due to the recursion protection
that checks to make sure there's no re-entrant events at the same level
of context).
The only issue with having function tracing enabled, is that it may add
a breakpoint when it gets turned on or off. And that tracing_off()
doesn't prevent that.
tracepoints still use RCU of some kind, and the protection there has
nothing to do with whether a trace point does recording or not.
-- Steve
next prev parent reply other threads:[~2020-02-18 23:17 UTC|newest]
Thread overview: 28+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-02-18 17:31 [RFC] #MC mess Borislav Petkov
2020-02-18 18:11 ` Steven Rostedt
2020-02-18 19:50 ` Borislav Petkov
2020-02-18 20:08 ` Steven Rostedt
2020-02-18 20:30 ` Peter Zijlstra
2020-02-18 20:52 ` Borislav Petkov
2020-02-18 18:20 ` Luck, Tony
2020-02-18 19:51 ` Borislav Petkov
2020-02-18 19:54 ` Luck, Tony
2020-02-18 20:00 ` Borislav Petkov
2020-02-18 20:05 ` Luck, Tony
2020-02-18 20:02 ` Peter Zijlstra
2020-02-18 20:09 ` Borislav Petkov
2020-02-18 20:11 ` Luck, Tony
2020-02-18 20:34 ` Peter Zijlstra
2020-02-18 21:49 ` Peter Zijlstra
2020-02-18 21:53 ` Peter Zijlstra
2020-02-18 22:41 ` Frederic Weisbecker
2020-02-18 22:40 ` Frederic Weisbecker
2020-02-18 23:17 ` Andy Lutomirski
2020-02-18 23:10 ` Andy Lutomirski
2020-02-18 23:17 ` Steven Rostedt [this message]
2020-02-19 0:15 ` Andy Lutomirski
2020-02-19 8:15 ` Peter Zijlstra
2020-02-19 14:21 ` Steven Rostedt
2020-02-19 14:43 ` Borislav Petkov
2020-02-19 15:05 ` Peter Zijlstra
2020-02-19 15:20 ` Andy Lutomirski
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