From: "Roedel, Joerg" <Joerg.Roedel@amd.com>
To: Marcelo Tosatti <mtosatti@redhat.com>
Cc: Avi Kivity <avi@redhat.com>,
"kvm@vger.kernel.org" <kvm@vger.kernel.org>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH 2/2] KVM: MMU: Use base_role.nxe for mmu.nx
Date: Wed, 15 Sep 2010 10:48:33 +0200 [thread overview]
Message-ID: <20100915084833.GH17759@amd.com> (raw)
In-Reply-To: <20100914220836.GA3553@amt.cnet>
On Tue, Sep 14, 2010 at 06:08:37PM -0400, Marcelo Tosatti wrote:
>
> For tdp better set base_role.nxe to zero, otherwise duplicate tdp
> pagetables can be created if the guest switches between nx/non-nx.
>
This does not work because bit 63 is marked as reserved if base_role.nxe
is 0. If the walk_addr_generic function then runs with tdp enabled it
would report a set nx bit as a rsvd fault.
We also can't use is_nx() in those path because it does not distinguish
between l1 and l2 nx. Are there guests that switch the efer.nx bit
regularly enough so that it matters? If so I would suggest to drop this
patch and keep mmu.nx.
Joerg
--
AMD Operating System Research Center
Advanced Micro Devices GmbH Einsteinring 24 85609 Dornach
General Managers: Alberto Bozzo, Andrew Bowd
Registration: Dornach, Landkr. Muenchen; Registerger. Muenchen, HRB Nr. 43632
next prev parent reply other threads:[~2010-09-15 8:51 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2010-09-14 15:46 [PATCH 0/2] NPT virtualization follow-up Joerg Roedel
2010-09-14 15:46 ` [PATCH 1/2] KVM: MMU: Don't track nested fault info in error-code Joerg Roedel
2010-09-16 14:01 ` Avi Kivity
2010-09-14 15:46 ` [PATCH 2/2] KVM: MMU: Use base_role.nxe for mmu.nx Joerg Roedel
2010-09-14 22:08 ` Marcelo Tosatti
2010-09-15 8:48 ` Roedel, Joerg [this message]
2010-09-15 14:48 ` Marcelo Tosatti
2010-09-16 14:00 ` Avi Kivity
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