From mboxrd@z Thu Jan  1 00:00:00 1970
From: Radim =?utf-8?B?S3LEjW3DocWZ?= <rkrcmar@redhat.com>
Subject: Re: [PATCH 1/2] KVM: VMX: remove I/O port 0x80 bypass on Intel hosts
Date: Tue, 5 Dec 2017 22:32:07 +0100
Message-ID: <20171205213206.GE20099@flask>
References: <20171201182110.7143-1-jmattson@google.com>
Mime-Version: 1.0
Content-Type: text/plain; charset=us-ascii
Cc: kvm@vger.kernel.org, P J P <ppandit@redhat.com>,
        Andrew Honig <ahonig@google.com>
To: Jim Mattson <jmattson@google.com>
Return-path: <kvm-owner@vger.kernel.org>
Received: from mx1.redhat.com ([209.132.183.28]:49026 "EHLO mx1.redhat.com"
        rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP
        id S1751362AbdLEVcK (ORCPT <rfc822;kvm@vger.kernel.org>);
        Tue, 5 Dec 2017 16:32:10 -0500
Content-Disposition: inline
In-Reply-To: <20171201182110.7143-1-jmattson@google.com>
Sender: kvm-owner@vger.kernel.org
List-ID: <kvm.vger.kernel.org>

2017-12-01 10:21-0800, Jim Mattson:
> From: Andrew Honig <ahonig@google.com>
> 
> This fixes CVE-2017-1000407.
> 
> KVM allows guests to directly access I/O port 0x80 on Intel hosts.  If
> the guest floods this port with writes it generates exceptions and
> instability in the host kernel, leading to a crash.  With this change
> guest writes to port 0x80 on Intel will behave the same as they
> currently behave on AMD systems.
> 
> Prevent the flooding by removing the code that sets port 0x80 as a
> passthrough port.  This is essentially the same as upstream patch
> 99f85a28a78e96d28907fe036e1671a218fee597, except that patch was
> for AMD chipsets and this patch is for Intel.
> 
> Signed-off-by: Andrew Honig <ahonig@google.com>
> Signed-off-by: Jim Mattson <jmattson@google.com>

Fixes: fdef3ad1b386 ("KVM: VMX: Enable io bitmaps to avoid IO port 0x80 VMEXITs")
Cc: <stable@vger.kernel.org>

Applied, thanks.  The commit that introduced it boasted 3-5% performance
improvements when compiling the kernel -- have you noticed regressions?