Date: Fri, 5 Jan 2018 00:45:58 +0100 (CET)
From: Thomas Gleixner <tglx@linutronix.de>
To: Andrea Arcangeli <aarcange@redhat.com>
cc: Tim Chen <tim.c.chen@linux.intel.com>,
        Peter Zijlstra <peterz@infradead.org>,
        Andy Lutomirski <luto@kernel.org>,
        Linus Torvalds <torvalds@linux-foundation.org>,
        Greg KH <gregkh@linuxfoundation.org>,
        Dave Hansen <dave.hansen@intel.com>,
        Andi Kleen <ak@linux.intel.com>,
        Arjan Van De Ven <arjan.van.de.ven@intel.com>,
        linux-kernel@vger.kernel.org
Subject: Re: [PATCH 4/7] x86/idle: Disable IBRS entering idle and enable it
 on wakeup
In-Reply-To: <20180104234227.GB13348@redhat.com>
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References: <cover.1515086770.git.tim.c.chen@linux.intel.com> <50b92931dd3cd403d60e69533f5583bbdbbb88d0.1515086770.git.tim.c.chen@linux.intel.com> <20180104224731.GE32035@hirez.programming.kicks-ass.net> <0ebb1848-c3ab-f636-f6f9-67716e814915@linux.intel.com>
 <20180104234227.GB13348@redhat.com>
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On Fri, 5 Jan 2018, Andrea Arcangeli wrote:

> On Thu, Jan 04, 2018 at 03:22:09PM -0800, Tim Chen wrote:
> > No one should be calling this with IRQs enabled.  This check is probably
> > just paranoid.  I can get rid of it.
> 
> Yes, confirmed.
> 
> > It probably doesn't matter as we will be switching the check
> > to the spec_ctrl_ibrs a couple of patches later. 
> 
> The other problem with static_cpu_has is later the code intends to
> support the cpuid rescan post late microcode update which will set
> bits in boot_cpu_data (and transfer them to each cpu_has). If we'd
> only support early microcode update static_cpu_has should have been ok
> too.

What's the problem to make the early update mandatory for this?

Thanks,

	tglx