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Date: Sun, 14 Jan 2018 14:27:28 +0100
From: Greg KH <greg@kroah.com>
To: Ingo Molnar <mingo@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>,
        Thomas Gleixner <tglx@linutronix.de>,
        linux-kernel@vger.kernel.org, Vince Weaver <vince@deater.net>,
        torvalds@linux-foundation.org, robert@swiecki.net,
        luto@amacapital.net, hughd@google.com,
        Alexander Shishkin <alexander.shishkin@linux.intel.com>
Subject: Re: [PATCH] x86,perf: Disable intel_bts when PTI
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On Sun, Jan 14, 2018 at 01:54:44PM +0100, Ingo Molnar wrote:
> 
> * Greg KH <greg@kroah.com> wrote:
> 
> > On Sun, Jan 14, 2018 at 11:27:13AM +0100, Peter Zijlstra wrote:
> > > 
> > > The intel_bts driver does not use the 'normal' BTS buffer we allocated
> > > space for in the cpu_entry_area but instead uses the memory allocated
> > > for the perf AUX buffer.
> > > 
> > > This obviously comes apart when using PTI because then the kernel
> > > mapping; which includes that AUX buffer memory; disappears.
> > > 
> > > For now disable this driver when PTI is enabled, we'll try and sort
> > > something out later.
> > > 
> > > Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
> > > Reported-by: Vince Weaver <vincent.weaver@maine.edu>
> > > Reported-by: Robert Święcki <robert@swiecki.net>
> > > Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
> > 
> > Can you add a:
> > 	Cc: stable <stable@vger.kernel.org>
> > please?
> 
> Note that these fixes are all going into tip:x86/pti, which is still a backporting 
> friendly linear set of commits that should all be backported.
> 
> So once 99a9dc98ba52 goes upstream, all of v4.14..99a9dc98ba52 the remaining bits 
> can go to -stable as well.
> 
> Will keep you updated about the latest status periodically, right now the latest 
> that is already upstream is:
> 
>   de791821c295: x86/pti: Rename BUG_CPU_INSECURE to BUG_CPU_MELTDOWN
> 
> i.e. all 194 commits in the v4.14..de791821c295 range should be queued up for 
> -stable. (And most of them already are.)

I hope I got all of those in that branch already, as I've been watching
it :)

> There are 28 new commits in tip:x86/pti that will (hopefully) go upstream later 
> today.

Great, again, thanks for doing it this way, it has made it much easier
for me.

greg k-h