From: Joerg Roedel <joro@8bytes.org>
To: Avi Kivity <avi@qumranet.com>
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 11:05:17 +0100 [thread overview]
Message-ID: <20080127100517.GC32677@8bytes.org> (raw)
In-Reply-To: <479C540A.8020003@qumranet.com>
On Sun, Jan 27, 2008 at 11:51:06AM +0200, Avi Kivity wrote:
> Joerg Roedel wrote:
> >
> >> What happens to lazy fpu if we don't trap cr0 changes?
> >>
> >> Perhaps it's worth disabling lazy fpu with npt.
> >>
> >
> > It should be implicitly disabled with npt because accesses to cr3 are
> > not intercepted anymore. The svm_set_cr3 function is the only place
> > which disables fpu switching.
> >
>
> Okay. We may want to investigate enabling it later, but no hurry now.
>
> 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. Cr4.pce can be
accessible for the guests because there is no way for them to access the
performance counter MSRs. But I am not sure about MCE, I will check
that.
WARNING: multiple messages have this Message-ID (diff)
From: Joerg Roedel <joro-zLv9SwRftAIdnm+yROfE0A@public.gmane.org>
To: Avi Kivity <avi-atKUWr5tajBWk0Htik3J/w@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 11:05:17 +0100 [thread overview]
Message-ID: <20080127100517.GC32677@8bytes.org> (raw)
In-Reply-To: <479C540A.8020003-atKUWr5tajBWk0Htik3J/w@public.gmane.org>
On Sun, Jan 27, 2008 at 11:51:06AM +0200, Avi Kivity wrote:
> Joerg Roedel wrote:
> >
> >> What happens to lazy fpu if we don't trap cr0 changes?
> >>
> >> Perhaps it's worth disabling lazy fpu with npt.
> >>
> >
> > It should be implicitly disabled with npt because accesses to cr3 are
> > not intercepted anymore. The svm_set_cr3 function is the only place
> > which disables fpu switching.
> >
>
> Okay. We may want to investigate enabling it later, but no hurry now.
>
> 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. Cr4.pce can be
accessible for the guests because there is no way for them to access the
performance counter MSRs. But I am not sure about MCE, I will check
that.
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next prev parent reply other threads:[~2008-01-27 10:05 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 ` Joerg Roedel [this message]
2008-01-27 10:05 ` Joerg Roedel
2008-01-27 10:24 ` [kvm-devel] " Avi Kivity
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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