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Date: Fri, 2 Feb 2018 13:02:53 -0500
From: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
To: KarimAllah Ahmed <karahmed@amazon.de>
Cc: kvm@vger.kernel.org, linux-kernel@vger.kernel.org, x86@kernel.org,
        Asit Mallick <asit.k.mallick@intel.com>,
        Arjan Van De Ven <arjan.van.de.ven@intel.com>,
        Dave Hansen <dave.hansen@intel.com>, Andi Kleen <ak@linux.intel.com>,
        Andrea Arcangeli <aarcange@redhat.com>,
        Linus Torvalds <torvalds@linux-foundation.org>,
        Tim Chen <tim.c.chen@linux.intel.com>,
        Thomas Gleixner <tglx@linutronix.de>,
        Dan Williams <dan.j.williams@intel.com>,
        Jun Nakajima <jun.nakajima@intel.com>,
        Paolo Bonzini <pbonzini@redhat.com>,
        David Woodhouse <dwmw@amazon.co.uk>,
        Greg KH <gregkh@linuxfoundation.org>,
        Andy Lutomirski <luto@kernel.org>, Ashok Raj <ashok.raj@intel.com>
Subject: Re: [PATCH v6 5/5] KVM: SVM: Allow direct access to
 MSR_IA32_SPEC_CTRL
Message-ID: <20180202180253.GU28192@char.us.oracle.com>
References: <1517522386-18410-1-git-send-email-karahmed@amazon.de>
 <1517522386-18410-6-git-send-email-karahmed@amazon.de>
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On Thu, Feb 01, 2018 at 10:59:46PM +0100, KarimAllah Ahmed wrote:
> [ Based on a patch from Paolo Bonzini <pbonzini@redhat.com> ]
> 
> ... basically doing exactly what we do for VMX:
> 
> - Passthrough SPEC_CTRL to guests (if enabled in guest CPUID)
> - Save and restore SPEC_CTRL around VMExit and VMEntry only if the guest
>   actually used it.
> 
> Cc: Asit Mallick <asit.k.mallick@intel.com>
> Cc: Arjan Van De Ven <arjan.van.de.ven@intel.com>
> Cc: Dave Hansen <dave.hansen@intel.com>
> Cc: Andi Kleen <ak@linux.intel.com>
> Cc: Andrea Arcangeli <aarcange@redhat.com>
> Cc: Linus Torvalds <torvalds@linux-foundation.org>
> Cc: Tim Chen <tim.c.chen@linux.intel.com>
> Cc: Thomas Gleixner <tglx@linutronix.de>
> Cc: Dan Williams <dan.j.williams@intel.com>
> Cc: Jun Nakajima <jun.nakajima@intel.com>
> Cc: Paolo Bonzini <pbonzini@redhat.com>
> Cc: David Woodhouse <dwmw@amazon.co.uk>
> Cc: Greg KH <gregkh@linuxfoundation.org>
> Cc: Andy Lutomirski <luto@kernel.org>
> Cc: Ashok Raj <ashok.raj@intel.com>
> Signed-off-by: KarimAllah Ahmed <karahmed@amazon.de>

Reviewed-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
> +	{ .index = MSR_IA32_SPEC_CTRL,			.always = false },


This .always = [false|true] field keeps throwing me off.

So glad: https://www.spinics.net/lists/kvm/msg161606.html explains it better.