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From: KY Srinivasan <kys@microsoft.com>
To: KY Srinivasan <kys@microsoft.com>, "Michael S. Tsirkin" <mst@redhat.com>
Cc: "olaf@aepfle.de" <olaf@aepfle.de>,
	"gregkh@linuxfoundation.org" <gregkh@linuxfoundation.org>,
	"jasowang@redhat.com" <jasowang@redhat.com>,
	"x86@kernel.org" <x86@kernel.org>,
	"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
	"bp@alien8.de" <bp@alien8.de>, Jan Beulich <JBeulich@suse.com>,
	"hpa@zytor.com" <hpa@zytor.com>,
	"apw@canonical.com" <apw@canonical.com>,
	"devel@linuxdriverproject.org" <devel@linuxdriverproject.org>,
	"tglx@linutronix.de" <tglx@linutronix.de>
Subject: RE: [PATCH 2/3] X86: Add a check to catch Xen emulation of Hyper-V
Date: Thu, 18 Apr 2013 13:30:56 +0000	[thread overview]
Message-ID: <beb28777dcbe4bfb9cc5cc77baba6ec0@SN2PR03MB061.namprd03.prod.outlook.com> (raw)
In-Reply-To: <cf53931949684c509dc30588ad77a7a9@SN2PR03MB061.namprd03.prod.outlook.com>



> -----Original Message-----
> From: devel [mailto:devel-bounces@linuxdriverproject.org] On Behalf Of KY
> Srinivasan
> Sent: Thursday, April 18, 2013 9:23 AM
> To: Michael S. Tsirkin
> Cc: olaf@aepfle.de; gregkh@linuxfoundation.org; jasowang@redhat.com;
> x86@kernel.org; linux-kernel@vger.kernel.org; bp@alien8.de; Jan Beulich;
> hpa@zytor.com; apw@canonical.com; devel@linuxdriverproject.org;
> tglx@linutronix.de
> Subject: RE: [PATCH 2/3] X86: Add a check to catch Xen emulation of Hyper-V
> 
> 
> 
> > -----Original Message-----
> > From: Michael S. Tsirkin [mailto:mst@redhat.com]
> > Sent: Thursday, April 18, 2013 3:48 AM
> > To: KY Srinivasan
> > Cc: Jan Beulich; olaf@aepfle.de; bp@alien8.de; apw@canonical.com;
> > x86@kernel.org; tglx@linutronix.de; devel@linuxdriverproject.org;
> > gregkh@linuxfoundation.org; jasowang@redhat.com; linux-
> > kernel@vger.kernel.org; hpa@zytor.com
> > Subject: Re: [PATCH 2/3] X86: Add a check to catch Xen emulation of Hyper-V
> >
> > On Wed, Apr 17, 2013 at 04:28:36PM +0000, KY Srinivasan wrote:
> > >
> > >
> > > > -----Original Message-----
> > > > From: Jan Beulich [mailto:JBeulich@suse.com]
> > > > Sent: Wednesday, April 17, 2013 11:51 AM
> > > > To: KY Srinivasan; Michael S. Tsirkin
> > > > Cc: olaf@aepfle.de; bp@alien8.de; apw@canonical.com; x86@kernel.org;
> > > > tglx@linutronix.de; devel@linuxdriverproject.org;
> > gregkh@linuxfoundation.org;
> > > > jasowang@redhat.com; linux-kernel@vger.kernel.org; hpa@zytor.com
> > > > Subject: RE: [PATCH 2/3] X86: Add a check to catch Xen emulation of Hyper-
> V
> > > >
> > > > >>> On 17.04.13 at 17:31, KY Srinivasan <kys@microsoft.com> wrote:
> > > > > If Xen were to change where it would not unconditionally emulate Hyper-
> V,
> > I
> > > > > would not be opposed to taking
> > > > > this check out.
> > > >
> > > > But it doesn't do this unconditionally, only upon admin request.
> > >
> > > >From the discussion we had a couple of months ago, the default setting was
> to
> > enable
> > > Hyper-V emulation for all guests. If this is not the case, we ought to be able to
> > drop this.
> > > However, I think it is not reasonable to add additional checks (in addition to
> > hypervisor check)
> > > to customize the run-time in the guest for the specific Hypervisor.
> > >
> > > Regards,
> > >
> > > K. Y
> >
> > Parse error. What are you trying to say? I'm just saying it's best to do
> > things in the way that make it possible for Xen to implement hyperv in a
> > more complete way in the future and have things just work
> > and in a way that does not change guest/hypervisor interface.
> 
> There is no error to parse here. I need to setup the vmbus interrupt before I
> can contact the host. As I said I am fine with dropping this check if Xen behavior is
> changed appropriately. We have a mechanism for hypervisor detection and a
> mechanism for discovering features within a hypervisor. Once we confirm the
> existence of a specific hypervisor, we ought to be able to do what is needed for
> that hypervisor (unless the hypervisor feature flag precludes it) without having to
> go through hoops to discover if we are in a hypervisor emulation mode where
> the emulation
> may not be complete. In this particular case, the need for VMBUS related
> infrastructure cannot be
> currently determined via the feature detection mechanism.
> 
> For features that cannot be detected via CPUID feature bits, we can use some
> other CPUID based
> mechanism to discriminate. For instance in the case under discussion, I could
> install
> hyperv_callback_vector only if we are on an environment that supports the
> vmbus infrastructure.
> Unfortunately there is no positive test for this. The best we can do is a negative
> test. I could move the
> Xen check and conditionally install the hyperv_callback vector.

Michael,

I think I can address the problem you have raised. I will send a patch out soon.

Regards,

K. Y
> 
> Regards,
> 
> K. Y
> 
> 
> >
> > > >
> > > > Jan
> > > >
> > > >
> > >
> >
> 
> 
> _______________________________________________
> devel mailing list
> devel@linuxdriverproject.org
> http://driverdev.linuxdriverproject.org/mailman/listinfo/devel
> 



  reply	other threads:[~2013-04-18 13:33 UTC|newest]

Thread overview: 55+ 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
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 [this message]
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
  -- strict thread matches above, loose matches on Subject: below --
2013-01-30  0:51 K. Y. Srinivasan
2013-01-30  0:51 ` [PATCH 1/3] x86: Hyper-V: register clocksource only if its advertised K. Y. Srinivasan
2013-01-30  0:51   ` [PATCH 2/3] X86: Add a check to catch Xen emulation of Hyper-V K. Y. Srinivasan
2013-01-30  8:53     ` Jan Beulich
2013-01-30 18:12       ` KY Srinivasan
2013-01-30 18:19         ` H. Peter Anvin
2013-01-31  7:37         ` Jan Beulich
2013-01-31 14:46           ` KY Srinivasan
2013-01-31 15:53             ` KY Srinivasan
2013-01-31 16:45               ` Jan Beulich
2013-01-31 18:29                 ` H. Peter Anvin
2013-01-31 21:41       ` H. Peter Anvin
2013-02-01 13:19         ` Stefano Stabellini
2013-02-01 15:10           ` KY Srinivasan
2013-02-01 19:34             ` KY Srinivasan

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