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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 10:52:32 +0200	[thread overview]
Message-ID: <20110530085232.GL30513@elte.hu> (raw)
In-Reply-To: <4DE358BF.2000902@redhat.com>


* 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.]

Thanks,

	Ingo

  reply	other threads:[~2011-05-30  8:52 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 [this message]
2011-05-30  8:53           ` Avi Kivity
2011-05-30  8:57             ` Ingo Molnar
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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