Date: Fri, 5 Jan 2018 00:42:27 +0100
From: Andrea Arcangeli <aarcange@redhat.com>
To: Tim Chen <tim.c.chen@linux.intel.com>
Cc: Peter Zijlstra <peterz@infradead.org>,
        Thomas Gleixner <tglx@linutronix.de>,
        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
Message-ID: <20180104234227.GB13348@redhat.com>
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>
MIME-Version: 1.0
Content-Type: text/plain; charset=us-ascii
Content-Disposition: inline
In-Reply-To: <0ebb1848-c3ab-f636-f6f9-67716e814915@linux.intel.com>
User-Agent: Mutt/1.9.2 (2017-12-15)
Sender: linux-kernel-owner@vger.kernel.org

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.