From: Avi Kivity <avi@qumranet.com>
To: Joerg Roedel <joro@8bytes.org>
Cc: kvm-devel@lists.sourceforge.net, linux-kernel@vger.kernel.org
Subject: Re: [kvm-devel] [PATCH 8/8] SVM: add support for Nested Paging
Date: Sun, 27 Jan 2008 12:24:35 +0200 [thread overview]
Message-ID: <479C5BE3.6060803@qumranet.com> (raw)
In-Reply-To: <20080127100517.GC32677@8bytes.org>
Joerg Roedel wrote:
>> On the other hand, we want to trap cr0 so the guest can't control the
>> cache disable bits. Also cr4.pce and cr4.mce.
>>
>
> Is it a problem when the guest disables caching? It disables it only in
> its own context because it has its own copy of cr0.
Some Intel processors have a mode where cache coherency is no longer
preserved, and we need to prevent that. However from my reading of the
AMD manuals, cache coherency is preserved even with caching disabled, so
no real issue with disabling the cache.
> Cr4.pce can be
> accessible for the guests because there is no way for them to access the
> performance counter MSRs.
Yes. This was a red herring, cr0.pce only affects userspace rdpmc.
--
error compiling committee.c: too many arguments to function
WARNING: multiple messages have this Message-ID (diff)
From: Avi Kivity <avi-atKUWr5tajBWk0Htik3J/w@public.gmane.org>
To: Joerg Roedel <joro-zLv9SwRftAIdnm+yROfE0A@public.gmane.org>
Cc: kvm-devel-5NWGOfrQmneRv+LV9MX5uipxlwaOVQ5f@public.gmane.org,
linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org
Subject: Re: [PATCH 8/8] SVM: add support for Nested Paging
Date: Sun, 27 Jan 2008 12:24:35 +0200 [thread overview]
Message-ID: <479C5BE3.6060803@qumranet.com> (raw)
In-Reply-To: <20080127100517.GC32677-zLv9SwRftAIdnm+yROfE0A@public.gmane.org>
Joerg Roedel wrote:
>> On the other hand, we want to trap cr0 so the guest can't control the
>> cache disable bits. Also cr4.pce and cr4.mce.
>>
>
> Is it a problem when the guest disables caching? It disables it only in
> its own context because it has its own copy of cr0.
Some Intel processors have a mode where cache coherency is no longer
preserved, and we need to prevent that. However from my reading of the
AMD manuals, cache coherency is preserved even with caching disabled, so
no real issue with disabling the cache.
> Cr4.pce can be
> accessible for the guests because there is no way for them to access the
> performance counter MSRs.
Yes. This was a red herring, cr0.pce only affects userspace rdpmc.
--
error compiling committee.c: too many arguments to function
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next prev parent reply other threads:[~2008-01-27 10:24 UTC|newest]
Thread overview: 68+ messages / expand[flat|nested] mbox.gz Atom feed top
2008-01-25 20:53 [PATCH][RFC] SVM: Add Support for Nested Paging in AMD Fam16 CPUs Joerg Roedel
2008-01-25 20:53 ` Joerg Roedel
2008-01-25 20:53 ` [PATCH 1/8] SVM: move feature detection to hardware setup code Joerg Roedel
2008-01-25 20:53 ` Joerg Roedel
2008-01-25 20:53 ` [PATCH 2/8] SVM: add detection of Nested Paging feature Joerg Roedel
2008-01-25 20:53 ` Joerg Roedel
2008-01-25 20:53 ` [PATCH 3/8] SVM: add module parameter to disable Nested Paging Joerg Roedel
2008-01-25 21:35 ` [kvm-devel] " Anthony Liguori
2008-01-25 21:35 ` Anthony Liguori
2008-01-25 22:10 ` [kvm-devel] " Joerg Roedel
2008-01-25 22:10 ` Joerg Roedel
2008-01-26 18:38 ` [kvm-devel] " Avi Kivity
2008-01-26 18:38 ` Avi Kivity
2008-01-26 1:47 ` [kvm-devel] [PATCH 3/8] SVM: add module parameter to disable NestedPaging Nakajima, Jun
2008-01-26 1:47 ` Nakajima, Jun
2008-01-26 7:25 ` [kvm-devel] " Joerg Roedel
2008-01-26 7:25 ` Joerg Roedel
2008-01-26 9:49 ` [kvm-devel] " Alexey Eremenko
2008-01-26 9:49 ` Alexey Eremenko
2008-01-26 10:06 ` [kvm-devel] " Joerg Roedel
2008-01-26 10:06 ` Joerg Roedel
2008-01-26 16:36 ` [kvm-devel] " Anthony Liguori
2008-01-26 16:36 ` Anthony Liguori
2008-01-26 18:23 ` [kvm-devel] " Avi Kivity
2008-01-25 20:53 ` [PATCH 4/8] X86: export information about NPT to generic x86 code Joerg Roedel
2008-01-25 20:53 ` Joerg Roedel
2008-01-25 21:37 ` [kvm-devel] " Anthony Liguori
2008-01-25 21:37 ` Anthony Liguori
2008-01-25 21:40 ` [kvm-devel] " Anthony Liguori
2008-01-25 21:40 ` Anthony Liguori
2008-01-27 8:40 ` [kvm-devel] " Avi Kivity
2008-01-27 8:40 ` Avi Kivity
2008-01-25 20:53 ` [PATCH 5/8] MMU: make the __nonpaging_map function generic Joerg Roedel
2008-01-25 20:53 ` Joerg Roedel
2008-01-25 20:53 ` [PATCH 6/8] X86: export the load_pdptrs() function to modules Joerg Roedel
2008-01-25 20:53 ` Joerg Roedel
2008-01-25 20:53 ` [PATCH 7/8] MMU: add HAP support to the KVM MMU Joerg Roedel
2008-01-25 20:53 ` Joerg Roedel
2008-01-25 20:53 ` [PATCH 8/8] SVM: add support for Nested Paging Joerg Roedel
2008-01-25 20:53 ` Joerg Roedel
2008-01-27 8:52 ` [kvm-devel] " Avi Kivity
2008-01-27 8:52 ` Avi Kivity
2008-01-27 9:41 ` [kvm-devel] " Joerg Roedel
2008-01-27 9:41 ` Joerg Roedel
2008-01-27 9:51 ` [kvm-devel] " Avi Kivity
2008-01-27 9:51 ` Avi Kivity
2008-01-27 10:05 ` [kvm-devel] " Joerg Roedel
2008-01-27 10:05 ` Joerg Roedel
2008-01-27 10:24 ` Avi Kivity [this message]
2008-01-27 10:24 ` Avi Kivity
2008-01-25 21:32 ` [kvm-devel] [PATCH][RFC] SVM: Add Support for Nested Paging in AMD Fam16 CPUs Anthony Liguori
2008-01-25 21:32 ` Anthony Liguori
2008-01-25 22:47 ` [kvm-devel] " Joerg Roedel
2008-01-25 22:47 ` Joerg Roedel
2008-01-26 1:57 ` [kvm-devel] " Nakajima, Jun
2008-01-26 1:57 ` Nakajima, Jun
2008-01-27 8:57 ` [kvm-devel] " Avi Kivity
2008-01-27 8:57 ` Avi Kivity
2008-01-27 9:51 ` [kvm-devel] " Joerg Roedel
2008-01-27 9:51 ` Joerg Roedel
2008-01-28 3:20 ` [kvm-devel] " Jeremy Fitzhardinge
2008-01-28 3:20 ` Jeremy Fitzhardinge
2008-01-28 11:08 ` [kvm-devel] " Avi Kivity
2008-01-28 11:08 ` Avi Kivity
2008-02-07 12:09 ` [kvm-devel] " Joerg Roedel
2008-02-07 12:09 ` Joerg Roedel
2008-02-10 10:35 ` [kvm-devel] " Avi Kivity
2008-02-10 10:35 ` Avi Kivity
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