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From: Ingo Molnar <mingo@elte.hu>
To: Avi Kivity <avi@redhat.com>
Cc: "Yang, Wei Y" <wei.y.yang@intel.com>,
	Pekka Enberg <penberg@cs.helsinki.fi>,
	"kvm@vger.kernel.org" <kvm@vger.kernel.org>
Subject: Re: [Patch v5 1/4] Remove SMEP bit from CR4_RESERVED_BITS
Date: Mon, 30 May 2011 10:57:15 +0200	[thread overview]
Message-ID: <20110530085715.GN30513@elte.hu> (raw)
In-Reply-To: <4DE35B26.2000403@redhat.com>


* Avi Kivity <avi@redhat.com> wrote:

> On 05/30/2011 11:52 AM, Ingo Molnar wrote:
> >* Avi Kivity<avi@redhat.com>  wrote:
> >
> >>  >  Another option would be to try to set the SMEP bit *before* we
> >>  >  enable paging. In theory this should not confuse a Linux guest -
> >>  >  and while i have not tested it i *think* we let it survive in the
> >>  >  saved_cr4_features shadow variable. That would make guest
> >>  >  suspend/resume work out of box as well.
> >>
> >>  Is there any reason not to do it in a hidden way in kvm?  Why must
> >>  we play tricks?
> >
> > So do you have a suggestion of how to do this cleaner?
> >
> > Add an ioctl that allows a VCPU to be configured in a way to set 
> > a cr4 feature without the guest actually seeing that bit? 
> > [Assuming both cr4 reads and writes are fully captured by KVM and 
> > thus guest behavior is controllable.]
> 
> Yes, this was what I suggested before.  IIRC you liked it.

Oh, it wasn't clear to me that this was your preference as well - and 
i didnt see such a capability in this series [let me know if i 
blindly missed it] so i was wondering what the battle plan was fr 
that :-)

Thanks,

	Ingo

  reply	other threads:[~2011-05-30  8:57 UTC|newest]

Thread overview: 12+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2011-05-30  3:01 [Patch v5 1/4] Remove SMEP bit from CR4_RESERVED_BITS Yang, Wei Y
2011-05-30  7:40 ` Ingo Molnar
2011-05-30  7:49   ` Avi Kivity
2011-05-30  8:05     ` Ingo Molnar
2011-05-30  8:43       ` Avi Kivity
2011-05-30  8:52         ` Ingo Molnar
2011-05-30  8:53           ` Avi Kivity
2011-05-30  8:57             ` Ingo Molnar [this message]
2011-05-30  9:00               ` Avi Kivity
2011-06-01  7:18   ` Tian, Kevin
2011-06-01  7:46     ` Ingo Molnar
2011-06-01  7:55     ` Avi Kivity

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