linux-kernel - Re: [PATCH 4/7] KVM: vmx: Allow the guest to run with dirty debug registers

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Date:	Mon, 10 Mar 2014 13:24:10 +0100
From:	Paolo Bonzini <pbonzini@...hat.com>
To:	Radim Krčmář <rkrcmar@...hat.com>
CC:	linux-kernel@...r.kernel.org, kvm@...r.kernel.org,
	alex.williamson@...hat.com, mtosatti@...hat.com, gleb@...nel.org,
	jan.kiszka@...mens.com
Subject: Re: [PATCH 4/7] KVM: vmx: Allow the guest to run with dirty debug
 registers

Il 10/03/2014 13:17, Radim Krčmář ha scritto:
>> > I considered this, but decided that it's unlikely for emulation to
>> > be faster than hardware---especially on those AMD CPUs that lack
>> > decode assists (and it's good for VMX and SVM code to look as
>> > similar as possible).
> I meant to move it before the block that exits if there is the
> 'exception on access' bit set in cr7, so we wouldn't exit again right
> away on the actual access, which is quite likely.
> (Exiting without emulation was a great move.)
>

Ah yes, for the GD bit.  I don't know, it's quite unlikely that anyone 
will use it...  It's a feeble attempt at allowing virtualization of the 
debug registers without VMX.

Paolo
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