linux-kernel - Re: [PATCH -v2] target-i386: Reenable RDTSCP support on Opteron

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Message-ID: <20181220121018.GM19442@habkost.net>
Date:   Thu, 20 Dec 2018 10:10:18 -0200
From:   Eduardo Habkost <ehabkost@...hat.com>
To:     Borislav Petkov <bp@...en8.de>
Cc:     Daniel P. Berrangé <berrange@...hat.com>,
        Paolo Bonzini <pbonzini@...hat.com>,
        Jörg Rödel <joro@...tes.org>,
        Andre Przywara <andre.przywara@....com>,
        kvm ML <kvm@...r.kernel.org>,
        lkml <linux-kernel@...r.kernel.org>,
        Tom Lendacky <thomas.lendacky@....com>,
        Eric Blake <eblake@...hat.com>, qemu-devel@...gnu.org
Subject: Re: [PATCH -v2] target-i386: Reenable RDTSCP support on
 Opteron_G[345] CPU models CPU models

On Wed, Dec 12, 2018 at 09:08:03PM +0100, Borislav Petkov wrote:
> On Wed, Dec 12, 2018 at 05:52:35PM -0200, Eduardo Habkost wrote:
> > Why did you remove this entry from PC_COMPAT_2_4?
> > 
> > We must keep compatibility with old behavior of Opteron_G2 on
> > pc-2.4, even if the old behavior was incorrect.
> 
> Ok, hunk reverted. v2 below.
> 
> Thx.
> 
> ---
> From: Borislav Petkov <bp@...e.de>
> 
> The missing functionality was added ~3 years ago with the Linux commit
> 
>   46896c73c1a4 ("KVM: svm: add support for RDTSCP")
> 
> so reenable RDTSCP support on those CPU models.
> 
> Opteron_G2 - being family 15, model 6, doesn't have RDTSCP support
> (the real hardware doesn't have it. K8 got RDTSCP support with the NPT
> models, i.e., models >= 0x40).
> 
> Document the host's minimum required kernel version, while at it.
> 
> Signed-off-by: Borislav Petkov <bp@...e.de>

Queued, thanks.

-- 
Eduardo