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
>
next prev parent 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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