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From: Avi Kivity <avi@redhat.com>
To: Peter Maydell <peter.maydell@linaro.org>
Cc: kvm <kvm@vger.kernel.org>,
	patches@linaro.org, Marcelo Tosatti <mtosatti@redhat.com>,
	Alexander Graf <agraf@suse.de>,
	qemu-devel@nongnu.org, Jan Kiszka <jan.kiszka@web.de>
Subject: Re: [Qemu-devel] [PATCH] kvm: Move kvm_allows_irq0_override() to target-i386
Date: Mon, 23 Jul 2012 17:30:06 +0300	[thread overview]
Message-ID: <500D5FEE.1010006@redhat.com> (raw)
In-Reply-To: <CAFEAcA_WCT1VLMSLjDyfWKw1=8gzoAT+di5LtHytDEYtYGZQbA@mail.gmail.com>

On 07/23/2012 04:50 PM, Peter Maydell wrote:
>>
>> Yet.
> 
> There is no mechanism in the virtualization extensions to either
> trap on or present a false value for guest accesses to the CPSR
> mode bits. So you can't make the guest OS think it is in Hypervisor
> mode. Therefore you can't provide the guest with the virtualization
> extensions. (The same argument applies for Monitor mode and means
> you can't provide the Security extensions (TrustZone) to the guest
> either.) I guess you could handle all code in the guest hypervisor
> under TCG but implementing a hybrid TCG+KVM mode would be a lot
> of effort and probably not really perform very well anyway...

Gaah, people add virtualization extensions to fix an ISA's
non-virtualizability, then do the same mistake again.

But I was only joking.  Nested virtualization is interesting technically
but so far I haven't seen any huge or even small uptake.

-- 
error compiling committee.c: too many arguments to function

  reply	other threads:[~2012-07-23 14:30 UTC|newest]

Thread overview: 40+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2012-07-20 19:14 [Qemu-devel] [PATCH] kvm: Move kvm_allows_irq0_override() to target-i386 Peter Maydell
2012-07-21  6:57 ` Jan Kiszka
2012-07-21  8:54   ` Peter Maydell
2012-07-21  9:14     ` Jan Kiszka
2012-07-21  9:30       ` Peter Maydell
2012-07-21  9:44         ` Jan Kiszka
2012-07-21  9:56           ` Peter Maydell
2012-07-21 10:22             ` Jan Kiszka
2012-07-21 10:53               ` Peter Maydell
2012-07-21 11:08                 ` Jan Kiszka
2012-07-21 12:17                   ` Peter Maydell
2012-07-21 12:35                     ` Jan Kiszka
2012-07-21 12:57                       ` Peter Maydell
2012-07-21 13:16                         ` Jan Kiszka
2012-07-23 12:04                           ` Cornelia Huck
2012-07-23 12:18                             ` Avi Kivity
2012-07-23 12:25                               ` Peter Maydell
2012-07-23 12:31                                 ` Avi Kivity
2012-07-23 12:34                                   ` Avi Kivity
2012-07-23 13:06                               ` Cornelia Huck
2012-07-23 13:14                                 ` Avi Kivity
2012-07-23 13:55                                   ` Cornelia Huck
2012-07-23 14:27                                     ` Avi Kivity
2012-07-23 15:01                                       ` Cornelia Huck
2012-07-23 12:26     ` Avi Kivity
2012-07-23 12:58       ` Peter Maydell
2012-07-23 13:09         ` Avi Kivity
2012-07-23 13:27           ` Peter Maydell
2012-07-23 13:38             ` Avi Kivity
2012-07-23 13:50               ` Peter Maydell
2012-07-23 14:30                 ` Avi Kivity [this message]
2012-07-23 17:58                   ` Peter Maydell
2012-07-24  8:50                     ` Avi Kivity
2012-07-24  8:54                       ` Peter Maydell
2012-07-24  8:58                         ` Jan Kiszka
2012-07-23 15:19       ` Peter Maydell
2012-07-23 16:55         ` Jan Kiszka
2012-07-23 17:41           ` Peter Maydell
2012-07-23 17:51             ` Jan Kiszka
2012-07-24  8:56         ` Avi Kivity

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