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From: "Michael S. Tsirkin" <mst@redhat.com>
To: Victor Miasnikov <vvm@tut.by>
Cc: "K. Y. Srinivasan" <kys@microsoft.com>,
	x86@kernel.org, gregkh@linuxfoundation.org,
	linux-kernel@vger.kernel.org, devel@linuxdriverproject.org,
	olaf@aepfle.de, apw@canonical.com, jasowang@redhat.com,
	tglx@linutronix.de, hpa@zytor.com, JBeulich@suse.com,
	bp@alien8.de
Subject: Re: KVM  "Hyper-V emulation"   -- this can be related "Linux on Hyper-V" ? Or  "KVM emulates Hyper-V" as  "Hyper-V emulates Hyper-V" ? Re: [PATCH 2/3] X86: Add a check to catch Xen emulation of Hyper-V
Date: Wed, 17 Apr 2013 13:16:17 +0300	[thread overview]
Message-ID: <20130417101617.GF3881@redhat.com> (raw)
In-Reply-To: <39D7C3658A5B4979A3F025E1D944E743@local.st.by>

On Wed, Apr 17, 2013 at 12:10:01PM +0300, Victor Miasnikov wrote:
> Question is very simple:  Hyper-V users/sysadmins need wait patch a-la this:
> 
> ==
> KVM emulates Hyper-V to host enlightened Windows. Looks like this
> emulation may be turned on by default even for Linux guests. Check and
> fail Hyper-V detection if we are on KVM.

> [ hpa: the problem here is that KVM doesn't emulate Hyper-V well
>  enough, and if the KVM support isn't compiled in, we end up stubling
>  over the Hyper-V emulation and try to activate it -- and it fails. ]
> 
> . . .

What's emulated not well enough?

> + /*
> +  * KVM emulates Hyper-V to support enlightened Windows.
> +  * Check to see first if we are on a KVM Hypervisor.
> +  */

If the hypervisor says it's Hyper-V, that's because it wants
guests to use Hyper-V. I don't see why is guest second-guessing
this a good idea.

> + if (KVM_cpuid_base())
> +  return false;
> +
> ==
> 
> 
> Or  "KVM emulates Hyper-V" as  "Hyper-V emulates Hyper-V" ?
> 
> 
> Best regards, Victor Miasnikov
> Blog:  http://vvm.blog.tut.by/
> 
> P.S.

No.  You are using Hyper-V, not the KVM emulation of it.  No patches
dealing with this emulation should have any effect on you.

-- 
MST

  reply	other threads:[~2013-04-17 11:15 UTC|newest]

Thread overview: 43+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2013-02-04  1:21 [PATCH 0/3] X86: Deliver Hyper-V interrupts on a seperate IDT vector K. Y. Srinivasan
2013-02-04  1:22 ` [PATCH 1/3] x86: Hyper-V: register clocksource only if its advertised K. Y. Srinivasan
2013-02-04  1:22   ` [PATCH 2/3] X86: Add a check to catch Xen emulation of Hyper-V K. Y. Srinivasan
2013-02-13  0:57     ` [tip:x86/hyperv] " tip-bot for K. Y. Srinivasan
2013-04-17  7:06     ` [PATCH 2/3] " Michael S. Tsirkin
2013-04-17  9:10       ` KVM "Hyper-V emulation" -- this can be related "Linux on Hyper-V" ? Or "KVM emulates Hyper-V" as "Hyper-V emulates Hyper-V" ? " Victor Miasnikov
2013-04-17 10:16         ` Michael S. Tsirkin [this message]
2013-04-17 12:12           ` Jan Beulich
2013-04-17 12:15             ` Michael S. Tsirkin
     [not found]             ` <CAP2xkNqGgbYz1gdS85xjA8gwROGY89fAsiaRiGSE90xnzjJ4Xw@mail.gmail.com>
2013-04-17 12:43               ` Michael S. Tsirkin
2013-04-17 14:08                 ` Victor Miasnikov
2013-04-17 13:20       ` KY Srinivasan
2013-04-17 12:48         ` Michael S. Tsirkin
2013-04-17 14:12           ` KY Srinivasan
2013-04-17 13:25             ` Michael S. Tsirkin
2013-04-17 14:34               ` KY Srinivasan
2013-04-17 13:48                 ` Michael S. Tsirkin
2013-04-17 15:31                   ` KY Srinivasan
2013-04-17 15:50                     ` Jan Beulich
2013-04-17 16:28                       ` KY Srinivasan
2013-04-18  7:48                         ` Michael S. Tsirkin
2013-04-18 13:23                           ` KY Srinivasan
2013-04-18 13:30                             ` KY Srinivasan
2013-04-17 13:52         ` Jan Beulich
2013-04-17 13:01           ` Michael S. Tsirkin
2013-04-17 13:11             ` Michael S. Tsirkin
2013-04-17 14:09             ` Jan Beulich
2013-04-17 15:17               ` H. Peter Anvin
2013-02-04  1:22   ` [PATCH 3/3] X86: Handle Hyper-V vmbus interrupts as special hypervisor interrupts K. Y. Srinivasan
2013-02-13  0:58     ` [tip:x86/hyperv] " tip-bot for K. Y. Srinivasan
2013-02-13  1:58       ` [tip:x86/hyperv] x86, hyperv: HYPERV depends on X86_LOCAL_APIC tip-bot for H. Peter Anvin
2013-02-13  2:05         ` KY Srinivasan
2013-02-13  2:56       ` [tip:x86/hyperv] X86: Handle Hyper-V vmbus interrupts as special hypervisor interrupts Yinghai Lu
2013-02-13  3:32         ` KY Srinivasan
2013-02-13  3:46           ` H. Peter Anvin
2013-02-13  3:49             ` KY Srinivasan
2013-02-13  3:54               ` H. Peter Anvin
2013-02-13  3:58                 ` KY Srinivasan
2013-02-13  4:42                   ` Yinghai Lu
2013-02-13 12:47                     ` KY Srinivasan
2013-02-13  0:56   ` [tip:x86/hyperv] x86: Hyper-V: register clocksource only if its advertised tip-bot for Olaf Hering
2013-02-05 11:16 ` [PATCH 0/3] X86: Deliver Hyper-V interrupts on a seperate IDT vector KY Srinivasan
2013-04-17 13:49 KVM "Hyper-V emulation" -- this can be related "Linux on Hyper-V" ? Or "KVM emulates Hyper-V" as "Hyper-V emulates Hyper-V" ? Re: [PATCH 2/3] X86: Add a check to catch Xen emulation of Hyper-V Victor Miasnikov

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