Messages in this thread | | | Date | Mon, 12 Feb 2018 14:06:40 +0100 | From | Peter Zijlstra <> | Subject | Re: [tip:x86/pti] x86/speculation: Use IBRS if available before calling into firmware |
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On Mon, Feb 12, 2018 at 12:27:19PM +0000, David Woodhouse wrote: > On Mon, 2018-02-12 at 12:50 +0100, Peter Zijlstra wrote:
> > Wait, we're doing firmware from NMI? That sounds like a _REALLY_ bad > > idea. > > And spin_lock_irqsave() too. Which is probably why I missed the fact > that this was being called in NMI context. > > Yay for HP and their persistent attempts to "value subtract" in their > firmware offerings. > > I'm tempted to drop that part of the patch and declare that if you're > using this driver, the potential for stray branch prediction when you > call into the firmware from the NMI handler is the *least* of your > problems.
We should probably mark it BROKEN or something, or move it into staging.
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