From mboxrd@z Thu Jan  1 00:00:00 1970
From: "Raj, Ashok" <ashok.raj@intel.com>
Subject: Re: [PATCH v5 2/5] KVM: x86: Add IBPB support
Date: Thu, 1 Feb 2018 09:00:25 -0800
Message-ID: <20180201170024.GA30307@araj-mobl1.jf.intel.com>
References: <1517427467-28567-1-git-send-email-karahmed@amazon.de>
 <1517427467-28567-3-git-send-email-karahmed@amazon.de>
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Cc: kvm@vger.kernel.org, linux-kernel@vger.kernel.org, x86@kernel.org,
        Asit Mallick <asit.k.mallick@intel.com>,
        Dave Hansen <dave.hansen@intel.com>,
        Arjan Van De Ven <arjan.van.de.ven@intel.com>,
        Tim Chen <tim.c.chen@linux.intel.com>,
        Linus Torvalds <torvalds@linux-foundation.org>,
        Andrea Arcangeli <aarcange@redhat.com>,
        Andi Kleen <ak@linux.intel.com>,
        Thomas Gleixner <tglx@linutronix.de>,
        Dan Williams <dan.j.williams@intel.com>,
        Jun Nakajima <jun.nakajima@intel.com>,
        Andy Lutomirski <luto@kernel.org>,
        Greg KH <gregkh@linuxfoundation.org>,
        Paolo Bonzini <pbonzini@redhat.com>,
        Peter Zijlstra <peterz@infradead.org>,
        David Woodhouse <dwmw@amazon.co.uk>,
        Ashok Raj <ashok.raj@intel.com>
To: KarimAllah Ahmed <karahmed@amazon.de>
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Hi Karim

Thanks for cracking at it through all the iterations.

On Wed, Jan 31, 2018 at 08:37:44PM +0100, KarimAllah Ahmed wrote:
> From: Ashok Raj <ashok.raj@intel.com>
> 
> The Indirect Branch Predictor Barrier (IBPB) is an indirect branch
> control mechanism. It keeps earlier branches from influencing
> later ones.

It might be better to split this patch into two parts.

- Just the place where we do IBPB barrier for VMX/SVM
- The msr get/set handling to comprehend guest, nested support etc.

The first part should be trivial so it can possibly make it into
tip/x86/pti branch sooner, while we rework the feedback to 
address this completely. 


Cheers,
Ashok